Example questions 1

Question 1

Describe the fire tetrahedron and explain the implications for extinguishing fire

Possible Marks = 4

Answer 1

The fire tetrahedron is made up of the following elements.
Heat
Fuel
Oxygen
Which make up the fire triangle
4. Chemical chain reaction (exothermic)

Fire can be extinguished by removing or controlling one or more of the parts of the fire tetrahedron
Heat can be removed or reduced by using water to cool the fire
Fuel can be removed by taking away the fuel source e.g. turning off a gas supply
Oxygen can be removed or reduced by smothering. e.g. placing a fire blanket over a fire
All three elements of the fire triangle (Heat, Oxygen, Fuel) must be in balance, removal of one of the elements described above will interrupt the chemical chain reaction (exothermic) which sustains the fire process.

Question 2

Describe the five stages through which a fire progresses and explain the role of passive fire protection at each stage

Answer 2

Ignition
Growth
Flashover
Fully developed
Decay

Ignition. Passive systems are included in the buildings construction that do not readily ignite and propagate flame. These products and systems will reduce the ability of a fire to develop into something larger, as well as reducing the ability of fire to pass around the internal surfaces of the building
Growth. Passive fire protection products and systems are usually made of materials that are non combustible or of limited combustibility which limits the fire load and available fuel. They also protect escape routes in order to allow safe evacuation of the buildings occupants.
Flashover. At this point (approx. 600degC) all combustible materials in the fire compartment will become involved. Passive fire protection systems now begin to resist the passage of fire from the compartment of origin into other parts of the building and insulate the structure against the effects of fire. Protected escape routes are maintained to allow for evacuation of occupants and to protect fire fighters should they need to enter the building.
Fully developed. Passive fire protection systems that have been tested and assessed to provide fire resistance to the specified period of time, contain fire in an effort to keep it as small as possible and limit fire spread. They also insulate the structure to maintain its stability/load bearing capacity and prevent collapse.
Decay. As the fire decays either as the result of intervention by fire fighters or it has consumed all the fuel that is available, areas may reignite particularly in unseen cavities. Passive fire protection materials and systems are less likely to do this, as they are usually none combustible or of limited combustibility, some passive fire protection systems can continue to provide protection to the structure beyond the designed fire resistance period.

Question 3

3. In relation to means of escape, define the following terms:
   A) Place of reasonable safety
   B) Travel distance
   (4 marks)

Answer 3

Place of reasonable safety
A place within a building or structure where, for a limited period of time, occupants will have some protection from the effects of fire.
Usually a corridor or stairway and will normally have a minimum of 30 minutes fire resistance
Will allow occupants to continue their escape to a place of complete safety
Travel Distance
Actual distance to be travelled by occupants from any point within a building to the nearest or final exit

Question 4

4. Internal compartmentation and fire resisting construction are examples of passive fire protection.
   A) Explain why these components are described as passive fire protection. (2 marks)

Answer 4

A) passive fire protection is “built in “ to the fabric of a building to provide fire resistance and insulate against the effects of fire, and/or contain fire within the compartment of origin
Passive fire protection systems do not require activation in order to carry out their function.

Question 5

5. Describe the content of a fire test report.
   Possible marks = 2

7 possible points

Answer 5

A fire test report is a scientific type document that describes:

1.Test specimen

2. Test standard
3. Installation of test sample
4. Detailed measurements of the test sample performance
5. Detailed measurements of the furnace pressures and temperature regime
6. Results of the test
7. Observations throughout the test

Question 6

5. Explain the limitations of a fire test report
   Possible marks = 2

5 answers

Answer 6

Limitations of such a report:

Only relates to the sample tested, without variation

Scientific language and presentation of data makes the report difficult to understand/interpret

Test regime is not representative of a real fire scenario, only a standard fire test curve

May not be to an internationally recognised test standard (e.g. they could be Ad Hoc)

There may be little or no control over the selection of test standards (BS regime)

Question 7

6. Describe steps that building managers can take to ensure that fire protection provisions in their premises are maintained

Answer 7

Monitoring of activities that might affect fire protection measures e.g. maintenance and changes to the building fabric

Inspection of compartmentation particularly when building works are required.

Ensure all materials used have appropriate certification

Ensure all building works are carried out by competent/qualified companies and individuals

Ensure tenants are aware of fire evacuation procedures

Ensure appropriate fire drills are carried out

Ensure policy documents and manuals are in place and up to date

Maintain all fire protection systems and keep appropriate records

Provide and maintain adequate signage

Question 8

7. Identify 3 types of sprinkler system and outline a typical building/situation where each one would be installed.
   (6 marks)

Answer 8

Wet pipe
No risk of freezing, quick to operate and required for multi storey/high rise buildings
Alternate
As the name suggests, they are full of water in the summer months but are drained in the winter and charged with air under pressure to avoid the risk of freezing. Used in buildings that are not heated e.g. warehouses
Dry Pipe
Used in buildings where freezing temperatures my be an issue. Will provide the coverage needed without the risk of bursts. Pipes are filled with air at all times, on activation the sprinkler head opens and the resulting change in pressure activates a release valve which then opens to allow water to flow into the system
Other measures could be..
Pre action.similar to dry pipe but water flow is activated by a heat/smoke detector
Deluge: Not strictly a sprinkler system. Designed to quickly extinguish a fire in a are of high risk. Usually in confined areas.

Question 9

8. Some passive fire protection systems depend on the operation of appropriate fire and smoke alarm systems to fulfil their intended role. Identify and describe three such systems.
   (6 marks)

Answer 9

Automatic door hold open/closure devices
Designed to hold open self closing fire doors or allow them to swing freely during normal use when activated by the fire alarm the door is released and closes to maintain the fire compartment. Particularly useful in areas of high traffic such as corridors.

Smoke control damper
Installed in smoke extraction ductwork in the line of the separating element, activated in the event of a fire incident to control the extraction of smoke from the effected compartment and direct the smoke from the building.

Active fire barriers
On detection of fire by an alarm system the active fire barrier is deployed in order to maintain compartmentation and/or protect a means of escape. Such fire barriers are usually out of sight during normal conditions giving flexibility to designers in open plan areas.

Question 10

9. Explain two different ways of flame retarding timber.
   (6 marks)

Answer 10

Surface preparations.
Intumescent coatings applied to the surface that react to heat to form an insulating layer or “char”. By blocking heat and oxygen they limit the level of combustion and surface spread of flame.

Impregnations
Usually offsite/factory based treatments that are designed to drive the flame retardant into the timber often involving vacuum or pressurised application techniques. Impregnations can improve the surface spread of flame and general “reaction to fire” performance. Timber should not be machined, planed or sanded once the treatment has been added as this will remove the protection that is in the surface layer of the timber.

Question 11

10. Describe the factors that effect the loadbearing capacity of the following building support systems in fire.

Concrete.

Answer 11

Concrete.
When exposed to high temperatures concrete structures may suffer from “Spalling” which is the process by which pieces of concrete break away under the pressure exerted as the trapped/bound water within the concrete turns to steam. Prolonged exposure to sever fires such as those experienced in tunnels may cause significant loss of concrete and expose reinforcing steel increasing the risk of structural collapse.

Question 12

10. Describe the factors that effect the loadbearing capacity of the following building support systems in fire.

Timber.

Answer 12

Timber.
Timber is know to have a measurable rate of char and this is used in order to design buildings that in most cases satisfy fire resistance requirements. The size and type of timber will dictate the level of resistance to fire of a timber element. In some circumstances timber structures can be further protected by the addition of appropriately fire tested products and systems

Question 13

10. Describe the factors that effect the loadbearing capacity of the following building support systems in fire.

Structural steel.

Answer 13

Structural steel.
Temperature: Historically seen as 550 deg C at which a loadbearing steel beam or column will typically be capable of supporting around 40% of the maximum design load.
Load: which will be dependent on the buildings design and intended use. The more load a steel element has to carry the lower the temperature at which it will begin to collapse.
Shape: the shape of a steel profile will have an effect on its ability to withstand heat. E.g Cellular beams tend to fail at lower temperatures and within the web, I& H sections usually fail in bending.

Question 14

11. Explain how intumescent coatings work and how they can contribute to the load bearing capacity of steel frames.

Answer 14

“Intumesce” means to swell. Intumescent coatings, also known as reactive coatings swell under the influence of heat to form an insulating layer or char. It is this char that provides the insulation to the steel section and keeps its temperature below the critical level.
Intumescent coatings are applied to primed steel, usually via airless spray to the required thickness as declared in the test/assessment data. On exposure to fire they expand to form the required level of insulation
Typically a thin film intumescent coating will expand to around 50 times its original dry film thickness (DFT)
Intumescent coatings are tested and assessed through standard fire resistance test regimes. The resulting assessment will provide the end user with a required thickness per steel section as dictated by the section factor expressed as A/V where A = the Area of a steel section that is exposed to fire and V = the Volume of a section, or the cross sectional area, per unit length. This thickness of coating should then be applied in order to achieve the specified period of fire resistance

Question 15

12. A) Explain the difference between box, profile and solid application of fire protection to steel

(2 marks)

Answer 15

A
Box- usually a board application forming a 3 or 4 sided encasement around a steel section. Section factor (A/V) will be lower as a result as of the reduced surface area (A) when compared to profiled applications. The ability to pass services through holes in the web will usually be lost as a result. Spray applied none reactive coatings can also be applied in a box configuration by using mesh or lath secured between the flange tips of an I or H section.
Profile- products and systems are installed following the shape of the steel section. Usually this is done with coatings but boards can be cut and installed to follow the profile. Section factor will be higher than an equivalent boxed application due to the increased surface area exposed to the fire when compared to boxed applications. (see above)
Solid – is a method of installing non reactive coatings in a way that fully fills the space between flanges

Question 16

B)Describe the role of fire resistant boardings when protecting structural steel sections

(2 marks)

Answer 16

B
Boards are fixed to steel beams and columns in order to insulate them from the high temperatures generated in fire. Fixing methods can vary even for the same product, all installations should be in line with the manufacturers published instructions.

Question 17

C) Describe two different types of materials used in the manufacture of fire resistant boards.
(2 marks)

Answer 17

C
Man made mineral wool (stone wool) – lightweight panels usually used on beams as they are soft and easily damaged
Calcium silicate- medium density products which are mechanically fixed around beams and columns where a higher level of durability is required. They are generally more able to deal with longer periods of fire resistance
Could also include gypsum based products (reinforced or not), Vermiculite boards, Ceramic blankets, Magnesium Oxide

Question 18

13. State and explain the three main criteria that materials/systems are assessed against when undergoing fire resistance testing to BS476.

Answer 18

REI
Stability (Load bearing Capacity) (R)
Integrity (E)
Insulation (I)

Stability (Load bearing capacity)is the ability of a material/structure to withstand the forces present in a fire and maintain its capability to support its designed load for the period of fire resistance.

Integrity is the ability of a material/structure to withstand fire exposure without cracking or gaps opening up to allow passage of hot gases, smoke and flames through to the non fire side

Insulation is the ability of a material/structure to limit heat transfer during exposure to fire. In the case of structural steel, materials/systems are required to keep the temperature of a beam or column below its critical temperature for the fire resistance period. In the case of compartment walls and floors, fire resistant structures must maintain temperatures on the non fire side such that they do not rise more than and average of 140 DegC above ambient, or above 180DegC at any one point.

Question 19

14. What are the two main purposes of compartment walls and floors?

Answer 19

Prevent fire spread by containing it in the compartment of origin in order to protect escaping occupants and maintain a safe means of escape and/or protect fire and rescue personnel.

Prevent small fires becoming large, on the basis that large fires are more dangerous than small ones to occupants, fire and rescue personnel, and people in the vicinity of the building

Question 20

15. Generally, fire resistant glazing falls within three tested classifications. Explain how each of the classifications are identified and how they differ from each other. (6 marks)

Answer 20

E. Integrity only glazing systems.

EW. Integrity with limited heat radiation capability

EI. Integrity and insulation

E. designed to resist the passage of fire and smoke from the compartment of origin for the specified period of fire resistance

EW. Provides integrity to the same extent as E but has additional, limited resistance to heat transfer to below 15kW/m2 on the unexposed side. Not currently recognised in the UK, but used elsewhere in Europe and the wider world to protect means of escape for a limited period of time in order to protect those evacuating a building.

EI. Provides integrity as per E but also full insulation to prevent heat transfer to the non fire side, such that the average temperature increase is limited to an average rise above ambient of 140degC or a maximum of 180degC

Question 21

16. Explain the difference in design and operation of curtain fire dampers and intumescent fire dampers.

Answer 21

Curtain Fire Dampers:
Constructed of a series of interlocking, metal blades which fold into the top of the damper assembly and hold it open in general use.
Released by either a thermally activated or fusible link in the event of fire, normally designed to activate at 72 degC +/-4 degC which allows the blades to descend closing off the space within the duct and sealing it against the passage of fire and smoke.
Separate fire resistance test evidence is required to support horizontal and vertical installations
Damper should be installed in the line of the separating element (wall or floor)

Intumescent Fire Dampers:
Incorporate components that expand in the event of fire to close off the space within the duct to prevent the passage of fire and hot smoke. If a cold smoke seal is required the intumescent damper cannot provide this on its own, an electro- mechanical device that is activated by a smoke sensor or a fire alarm must be fitted in this instance.
Damper should be installed in the line of the separating element (wall or floor)

Question 22

17. Ventilation ductwork offers little or no protection against fire spread. Explain three ways of maintaining the fire resistance of walls and floors penetrated by ductwork.
    Possible marks = 8

Answer 22

Method 1. Protection using fire dampers
Method 2. Protection using fire resistant enclosures
Method 3. Protection using fire resisting ductwork

Method 1: dampers are placed in the plane of the compartment wall or floor which are activated in the event of fire via either a fusible link which releases the damper under the influence of heat from the fire, or a mechanical damper which is released automatically on activation of a fire alarm or detector, closing the internal space within the ductwork and maintaining the fire compartment.

Method 2: Ductwork is enclosed in fire resistant construction such as a shaft or riser. Fire protection to the ductwork system is provided by the enclosure, compartmentation is maintained by fire stopping at walls and floor penetrations using appropriately tested and approved systems.

Method 3: Ductwork is constructed from materials that provide the necessary fire resistance. This can be metal ducts which are coated with fire resisting materials such as paints or boards. Or the ductwork itself can be constructed from fire resisting boards. The fire resisting ductworks fire performance should be demonstrated by appropriate and valid fire test evidence ideally supported by 3rd party certification of both the ductwork system and the installation company. Appropriately tested fire stopping solutions should be used where the ductwork passes through compartment walls and floors paying particular attention to smoke control requirements and the necessary support of the duct, and the firestopping required at the point where the duct passes through the separating element.

Question 23

18. Identify five different situations where fire stopping would be needed and describe an appropriate solution.
    (10 marks)

Answer 23

Penetration seals: required where services pass through a separating element (wall or floor)
Example: batt and mastic system incorporating appropriate pipe closures where plastic pipes pass through a compartment wall.
Linear Joint seals: required between fire resisting elements e.g. the junction between a floor and a wall.
Example: elastomeric expansion joint strip installed at the appropriate depth and width for the designed fire resistance period.
Small Cavity Barrier: Usually installed between two leaves of masonry to prevent the passage of fire in the unseen/inaccessible space
Large Cavity Barrier: Used to subdivide the space in a roof void or beneath a raised access floor.
Temporary/removable penetration seal: Installed to maintain compartmentation but can be easily removed in order to install more services.
Example: at the compartment wall beneath a raised floor in an office building where data cables are frequently added or changed. Often provided by the use of fire resistant bags/pillows.

Question 24

19. Explain the purpose, construction and design of a fire barrier system and how they differ from cavity barriers. (6 marks)

Answer 24

Fire barrier systems are a fire stopping element intend to continue the line of a fire compartment
They have the same fire resistance as the compartment wall or floor into which they are installed. (integrity and Insulation)

Cavity barriers are used to subdivide the space within a compartment and as a result they do not need to have the same level of insulation performance as a fire barrier. UK guidance currently requires that they provide minimum 15 minutes insulation
Cavity barriers can be large or small
Small: typically to seal the space between two leaves of masonry to prevent passage of fire and smoke within the unseen space
Large: typically used to subdivide the space within a roof structure

Question 25

20. State 6 components of a fire doorset or assembly and explain their role in maintaining fire performance
    Possible marks = 6

Answer 25

Door leaf: The main component of a fire door set or assembly, used as a means of access through a fire compartment wall during normal use. Must provide a barrier against the passage of fire. Fire resistance is usually 30 or 60 minutes Integrity, higher periods of fire resistance can be achieved.

Intumescent strips: Installed in the long edges and top edge of the leaf or frame. Expand under heat to seal the space between door leaf and frame to prevent passage of fire and hot smoke.

Smoke Seals: Installed around the edges of the door leaf to prevent passage of cold smoke. Can be brush or blade type

Hold open/closure device: usually fitted to the head of the door frame/leaf. Designed to hold the door in the open position in normal use. Closes to maintain fire integrity of the compartment wall on activation of a fire/smoke alarm.

Glazed panels: installed in the door or surrounding framework to allow visual assessment of the area beyond the door during normal usage. Must provide the same level of fire resistance as the rest of the door during a fire scenario. The glazed aperture will consist of the glass panel, and all the fixing details that make up the glazed assembly. Beading, sealant, glazing setting blocks, fixings are all important to the fire performance of the glazing panel.

Hinges: Normally 3 in number. Should be sufficient to support the weight and usage requirements of the door in normal use as well as in fire. All hinges should carry a CE mark as evidence of fitness for use. Usually have an intumescent pad or sealant between the back of the hinge plate and the door/doorframe to control passage of heat.

Question 26

21. Explain the design, purpose and operation of a fire shutter.
    (6 marks)

Answer 26

Usually constructed from multiple leaves of metal which are secured in position above an opening in a compartment wall or floor or in the structure around a shaft.

The shutter should provide the same fire resistance as the separating element into which it is installed

Usually fitted with a thermally activated self closing device or fusible link that under the effect of heat from a fire activates the closing mechanism in order to maintain the fire resistance of the separating element.

Can be connected to an alarm system or detection device which when activated would close the shutter

Should default to the closed position in the event of a power failure or similar

Should be designed and constructed such that the descent of the shutter is controlled

If the shutter represents more than 25% of the overall area of the separating element it should provide full insulation. E.g. It should insulate the non fire side such that temperatures do not increase more than an average of 140 deg C or a maximum of 180 deg C

Question 27

In relation to fire resistance, explain the difference between “insulation” and “integrity”. (4 marks)

Answer 27

Integrity - The ability of the structure to maintain its fire integrity to ensure that no gaps of sufficient size open up which allow penetration of hot gases, smoke and flames between one fire compartment and another.
Insulation – Insulation is the ability to protect the unexposed face of a compartment, i.e. the other side of a compartment wall to where the fire is burning, should not increase in temperature above an average of 140°C or by more than 180°C at any one point.

Question 28

One of the measures used in assessing the way in which a material will react to fire is the extent to which it is combustible. Identify three other factors that can be used in measuring how a material reacts to fire. (3 marks)

Answer 28

Spread flame (over their surface)
Release heat (rate of/fire propagation)
Produce flaming droplets and smoke (not used in UK regulations)
Ignitability

Question 29

Explain the issues and limitations that need to be taken into consideration when interpreting fire testing and assessments. (4 marks)

Answer 29

• First-party certification Where an individual or organization provides goods or services with an offer of assurance that they meet certain claims.
• Second-party certification An association to which the individual or organization belongs provides some assurance by virtue of membership.
• Third-party certification An independent assessment is undertaken by a Certification Body, themselves accredited by the United Kingdom Accreditation Service (UKAS in the UK), declaring that specified requirements pertaining to a product, person, process or management system have been met.

The limitations of testing and assessments is that they can be ad hoc and may not be internationally recognised.

Tests are carried out in a controlled environment and is therefore not a true reflection of a real-life scenario.

Scientific language make the test difficult to understand.

Only relates to the standard sample tested without variation.

Those making the assessments need to be competent and be able to demonstrate this competency.

Fire test reports are often used to demonstrate a product’s fire performance. However, fire test reports are only applicable to the product or construction as tested with only limited variations permitted in the direct field of application of the particular test method. Further, they have none of the quality control aspects of third-party certification.

Finally, fire test reports are often long and complicated documents which are not suitable for marketing purposes or for use by authorities having jurisdiction such as building control.

Question 30

Passive fire protections measures should be taken into account when developing plans for building projects. One reason for this is to ensure that the correct checks are carried out at the right times. Identify and explain two other reasons. (4 marks)

Answer 30

Passive fire protection is installed in the correct order, preventing unnecessary rework later which, in turn, may lead to an unsatisfactory ad-hoc solution being applied.

Fire stopping systems installed then IT knock holes through the compliant walls. By placing this work with specialists, and with careful programming, it is much more likely that the correct materials will be specified and installed, avoiding damage and rework.

Attempting to inspect and remedy deficient Passive Fire Protection at a late stage will prove extremely challenging and/or time consuming, since passive fire protection is often hidden or inaccessible once the building is complete.

It will also prove to be far more expensive than installing it correctly first time.

Contractors are required to provide certificates of conformity to demonstrate compliance with relevant regulations.

Question 31

a) Explain what is meant by the term “active fire protection” and state how active fire protection differs from passive fire protection. (3 marks)

Answer 31

Active fire protection is a form of protection measure that requires special energization or a command signal to operate. Passive fire protection is in built within the structure and doesn’t require activation to complete its role.

Question 32

b) Identify and describe two types of smoke detection system. (4 marks)

Answer 32

Optical Smoke Detectors – One of the most common form of smoke detectors and usually found in most domestic premises. This type of detector works on the principle of light. Using infrared, the detector detects smoke when the particles block light from reaching the sensor chamber.

Smoke Aspiration System – This system is extremely sensitive and monitors air quality by drawing air into a network of small pipes. These pipes then lead to a sampling chamber where a laser is used to detect the presence of smoke particles.

Question 33

Identify five locations in a building where emergency lighting should be located. (5 marks)

9 possible answers

Answer 33

• Each final exit door
• Escape routes
• Intersection of corridors (changes in direction)
• Outside each final exit and on external escape routes
• Emergency escape signs
• Stairways so that each flight receives adequate light
• Changes in floor level
• Windowless rooms and toilet accommodation
• Fire-fighting equipment

Question 34

Describe the insulating materials that can be used to protect structural timber and state the factors that affect the required thickness of the protective layer. (4 marks)

Answer 34

Exposed timber sections can be designed with additional ‘sacrificial’ timber to a section, so that the part exposed to fire can protect the inner material from fire damage while the outer part chars at a slow, predictable rate. Where this is not the case, structural elements, including mechanical fasteners, can be insulated from heat by covering them with one or more layers of fire resisting insulating material, for example gypsum plasterboard or a calcium silicate board, of a specified thickness. The thickness of the fire protective layer will be governed by the density and makeup of the structural element, e.g. solid timber, glulam, Laminated Veneer Lumber (LVL) etc

Question 35

a) Explain why the thickness of a steel structure needs to be considered when planning for appropriate fire resistance. (2 marks)

Answer 35

The thicker and heavier a steel section becomes the longer it will take to heat up, therefore the amount of structural fire protection required to control the steel temperature to below the critical level will be less than would be required for a thin lightweight section. Fires in buildings regularly exceed 1000°C within a relatively short period of time (30 – 60 minutes), yet heavily loaded steel loses its design margin of safety, (about 40%) at temperatures around 550°C regardless of the grade, and as its temperature rises further the loss of strength is rapid and significant.

Question 36

b) State and explain the “section factor” formula used when determining the length of fire resistance. (3 marks)

Answer 36

The length of fire resistance period is calculated based on the size and weight of the steel section using a formula known as the ‘Section Factor’ (A/V) where:
* A = Surface area of steel exposed to the fire per unit of length
* V = Volume of the section per unit length
In the past A/V has also been described as Hp/A (heated perimeter of the exposed cross section divided by the total cross-sectional area).

Question 37

a) State three advantages of applying intumescent coatings off-site. (3 marks)

Answer 37

Provides better quality control in terms of temperature and humidity.

Provides better quality control in both wet film as well as dry film readings.

No disruptions to other trades operating on site.

No risk to area due to overspray.

Question 38

b) State two challenges that can arise when intumescent coatings are applied off-site. (2 marks)

Answer 38

• Workshop handling and the transportation of steel members to the construction site must be done with care or risk damaging the paint.
• Possibly higher transportation costs.
• If the paint is damaged during transportation or installation, the applicators must re-apply it on site.

Question 39

Identify two different types of fire resisting floors and explain how each of them may be constructed in order to achieve the required fire resistance. (6 marks)

Answer 39

Fire-resisting floors may generally be considered under three primary types:

Timber joist floors
Timber joist floors will char above certain temperatures, the wood will be progressively but predictably consumed by fire. The timber thickness is critical to the structural performance in fire and therefore must be correctly specified. Timber char rate may typically range from 0.5 - 0.8 mm / minute. Fire resistance is usually afforded by a combination of protection to the underside and ensuring there is enough sacrificial timber in the joists. Underside protection will normally be provided by fire resistant board systems such as plasterboard or similar but other systems are available.

Concrete floors
Concrete floors contain entrapped moisture. They may well be reinforced with steel. In fire, the entrapped moisture will heat up and turn to steam. The steam pressure will increase and try to find relief by escaping from the concrete. The escape mechanism can be violent and large pieces of concrete may become detached by explosive spalling. Any steel reinforcement in the concrete will be initially protected by the concrete, until spalling exposes the steel and it will substantially expand to threaten the viability of use as a floor. The extent of concrete cover over reinforcement is therefore critical to the fire resistance available and must be correctly specified.

Composite floors
Composite floors generally consist of a profiled metal deck with a poured concrete topping which can perform differently in fire, because the metal base will conduct heat from fire laterally, and in so doing the metal face will attempt to expand. The rate of temperature increase in the critical parts of the floor may be lessened compared to concrete alone, however the composite floor will also be fixed through shear connectors to the supporting steel structure. During the fire, steam formed in the concrete may force out the metal decking, distorting it and causing gaps and subsequent failure, and whilst the steel reinforcement will transfer the load and the heat from fire, the composite structure may ultimately deform under the heat and sag under the load of the concrete.

The fire performance of all floors can be enhanced through the use of added passive fire protection systems, appropriate to the floor type.
These passive fire protection systems act to insulate the timber, concrete, or steel from the effects of fire for given periods of time. The protecting mechanism depends on the characteristics of the PFP system and careful design based on fire test evidence is essential. Manufacturers’ test evidence must be understood and incorporated into the specification to ensure that the anticipated performance is achieved. The choice of passive fire protection can also be important if the performance is not to be negated by deformation of the floor system. Some PFP materials will deform less well than others, which may lead to fracture under deformation in fire.

Question 40

Describe the considerations to be taken into account when selecting an active fire curtain for installation. (5 marks)

Answer 40

Active fire curtain barriers are normally used to provide compartmentation and to protect means of escape and may be installed in any type of building where these are required.

The following should be considered when looking to install an active fire curtain:
1. What level of fire resistance is required
2. Its intended purpose, provide compartmentation or to protect means of escape.

3. The overall size of the curtain
4. How it will be operated
5. How many motors are required to operate it
6. Whether or not vertical channels are required.
7. Ensure the curtain fails safe using gravity
8. Ensure there is a compliant alarm system that will be used to trigger the activation of the curtain

Question 41

State the performance requirements of a fire resisting suspended ceiling. (3 marks)

Answer 41

Not break or collapse during the early stages of a fire when evacuation and rescue operations can still be carried out.

Prevent surface spread of flame

Provide a period of fire resistance to protect the services that are likely running above the ceiling.

Stop fire passing through them either by flames or by heat conduction.

Question 42

Describe the situations where each of the following would be used to achieve fire stopping and give two examples of the fire stopping products that would be used:
a) penetration seals (4 marks)

Answer 42

a) Where services pass through fire separating elements and/or compartment walls or floors. For example a non combustible pipe penetrating through a wall or a cable penetration.

Stone wool products for fire-stopping are supplied in a number of forms; typically referred to as mats, batts, or pre-formed shapes.

Ablative coated stone wool batts/board, the ablative coating acts as a sacrificial layer designed to absorb/consume heat from a fire and release it in the form of a gas, to protect the underlining stone wool slab.

Sealant or mastic (for example silicone, acrylic) applied by a mastic gun or trowel applied into an opening and between/around suitable penetrating services.

Question 43

Describe the situations where each of the following would be used to achieve fire stopping and give two examples of the fire stopping products that would be used:
b) linear joint seals (4 marks)

Answer 43

b)Also known as Pre-formed elastomeric seals. Typically installed between fire resisting elements of building construction, for example the junction between a wall and a floor.
These are made from elastomeric foam sometimes encasing stone wool, and sometimes with reinforcing sheets on either side. The foam and/or the reinforcing sheets may be intumescent. These products are generally supplied in a strip form.
Sealant or mastic can also be used for linear joint seals. When used in linear joints where movement is expected, a sealant with the ability to accommodate the movement of the joint should be used so that a seal is maintained in service and during fire conditions.

Question 44

One method of fire stopping is bags/pillows. a) Describe this method of fire stopping and explain the installation process. (4 marks)

Answer 44

Bags/pillows or cushions are available in various sizes and shapes and are specified for use in temporary or permanent fire-stopping situations where services such as cables pass through walls and floors. Bags/pillows are made from non-combustible fabrics and enclose a filling material which may incorporate an intumescent material. FRICTION FIT!!!
Bags/pillows must be placed into the opening(s) using the correct orientation, packing density and overlap (staggered joints), to achieve the desired fire resistance. For wall penetrations, bags/pillows are normally self-supporting, but large openings with few penetrating services may require a steel retaining mesh for support on both sides of the penetration.

Question 45

One method of fire stopping is bags/pillows.

b) Describe the circumstances when this would be an appropriate option and state why this is the case. (2 marks)

Answer 45

Bags/pillows can be used wherever services, such as cables, penetrate a fire-resistant element. Since they are easily removed, they are particularly useful where services are frequently re-routed, and can be used as adaptable protection during construction work.

Question 46

Describe the factors to be considered when carrying out the installation of dampers. (4 marks)

Answer 46

Manufacturers installation instructions should be followed

Details may differ depending on the wall/floor construction

It is important that the dampers are appropriately supported and restrained back to the building element or adjacent structure through which it penetrates in a manner that maintains the support and restraint function in a fire condition and accommodates thermal movement in the cold state.

Dampers must also be in line with the building element unless the manufacturer has test data to the relevant part of EN 1366 that permits an ‘out of line’ installation.

Ensure there is adequate access to the damper for future maintenance

Question 47

Describe the differences between a fire damper and a smoke control damper. (6 marks)

Answer 47

Fire dampers are used to prevent fire and smoke spreading from one compartment to another through the ductwork that penetrates walls and floors. Normally, the fire damper is open, but in a fire, it closes. Dampers can be closed by fusible links (heat sensitive devices), which release a spring-activated mechanism, or motorised as part of a fire and smoke control system (Method 4). A third alternative is the use of intumescent dampers, comprising a matrix of material coated with intumescent that swells up and closes the opening on heating.
Smoke Control Dampers are single or multi-blade dampers that would generally have two positions - ‘open’ to allow smoke extraction or ‘closed’ to maintain the fire compartment. They do not have thermal release mechanism, relying on a ‘powered’ control system to ensure that they achieve the correct position.

The main difference is smoke control dampers don’t have a thermal release mechanism they are controlled by a powered system that allows the damper to seal against cold smoke and could be open or closed during a fire event to allow the smoke to be evacuated from the fire compartment and directed out of the building.
Fire dampers respond to heat, when the temperature reaches a set point the damper slams shut.Smoke dampers respond to the detection of smoke, and close automatically. They can also be activated remotely. They resist the passage of smoke, toxic gases and air through a fire barrier.

Question 48

Describe four situations when an automatic door hold open/closure device should operate. (4 marks)

Answer 48

In all cases, the automatic device should release the fire-resisting door allowing it to close effectively within its frame (latching securely if a latch is fitted) when any of the following conditions occur:
* The detection of smoke by an automatic detector
* The actuation of the fire detection/alarm system by manual means e.g. operation of break glass call point
* Any failure of the fire detection and alarm system
* Any electrical power failure

Question 49

Describe the features of steel fire doors and state two locations where such doors may be used. (4 marks)

Answer 49

Steel doors, depending on the design and core structure, can offer fire resistance periods of up to six hours, therefore they are often specified in industrial environments and where high-density traffic may be expected such as airports and shopping malls. Such door can be made from a honeycomb core to aid rigidity, or a semi ridged construction utilising a stone wool core, or ridged core utilising a mineral core, (which may also enable the door to meet the additional insulation requirement).

Question 50

Describe four checks that should be carried out in relation to the intumescent fire and smoke seals used on a fire door. (4 marks)

Answer 50

Ensure a mix and match approach hasn’t been adopted. It is important not to combine multiple different types on the same door as they react differently.

Check that perimeter gaps do not exceed 3mm

Check that ironmongery doesn’t interrupt smoke seals

Check base gaps of the door and whether the floor is uneven as this could determine whether a drop down seal is required.

Check product documentation to ensure the right product has been used.

Material of the door as metal doors may not require intumescent strips.

• Check they are in good condition * Full length and secure in the groove * If seals are badly finished, damaged or painted over then they must be replaced with exactly the same size and intumescent material that was originally specified * If the smoke seals have been replaced, they should be fitted in one continuous length if possible

Question 51

a) Describe the fire tetrahedron and explain the implications for fire. (4 marks)

Answer 51

The fire tetrahedron is made up of four elements, these are fuel, heat and oxygen which form to make the fire triangle. The fourth element is a chemical chain reaction that takes place when all three elements of the fire triangle combine. If you were to remove any element of the fire triangle by way of cooling the fire, starving it of oxygen or removing the fuel source the fire would seize to exist.

Question 52

b) Explain the term “exothermic reaction”. (2 marks)

Answer 52

An exothermic reaction is a chemical chain reaction that omits/releases heat. This exothermic reaction allows a fire to sustain itself.

Question 53

Explain the risks to human health associated with the inhalation of smoke. (4 marks)

Answer 53

As well as heat fires produce other products of combustion, for example smoke.

Smoke is the primary cause of death for indoor fires.

Hot smoke can cause burns to the respiratory system.

Smoke can cause irritation to the eyes and digestive system.

Smoke typically contains toxic gases such as carbon monoxide which is fatal as it irreversibly replaces oxygen in the blood.

Vapours created by fire and smoke can lead to poisoning as they are absorbed by the skin.

Question 54

Describe four factors that affect human behaviour when faced with a threat of fire in a building. (4 marks)

Answer 54

Herd Mentality – People have a tendency to copy the behaviours of others this is known as the herd mentality, if one person decides to panic this can lead to mass panic. If one person refuses to leave this could influence others to not evacuate, likewise if people start to evacuate in an orderly fashion then others will follow suit.

Knowledge of the building layout – people tend to try and exit a building the way they entered rather than using their closest fire exit. This could potentially put themselves in danger.

Family or friends within the same building but separated can lead to people trying to regroup/find each other rather than exiting the building immediately, this can put themselves and others in danger as the delay in evacuating could provide sufficient time for the fire to develop.

False Alarms – If the building is prone to false alarms people will start to ignore the alarm and fail to react properly in the event of a real fire.

Question 55

a) Define the term “means of escape”. (3 marks)

Answer 55

A “means of escape” can be defined asthe structural means whereby a safe route is provided for people to travel from any location in a building or structure to a place of safety without the need of outside assistance. Means of escape must be clearly identified by signage and be illuminated by emergency lighting to ensure safe egress should the power fail.

Question 56

b) Explain the role of passive fire protection in relation to means of escape. (4 marks)

Answer 56

The role of passive fire protection is to protect the means of escape for the designed period of fire resistance. This needs to be a minimum of 30 minutes but could be 60 minutes or more in some instances.

Means of escape can also provide a place of relative safety in the form of a corridor or stairwell, therefore passive fire protection protects people from the effects of fire until they reach ultimate safety.

Fire Doors are a great way to protect means of escape from the spread of fire and smoke. Fire doors will typically self close in the event of a fire preventing the fire from entering a means of escape.

Cross corridor doors are also a great way of preventing smoke spread along a means of escape (corridor).

Passive fire protection measures help to form compartments in a building these compartments divide a building into smaller manageable areas so in the event of a fire the fire is prevented from escalating to a larger fire. Smaller fires are easier to extinguish.

Question 57

In relation to fire resistance, explain what is meant by the term “stability” and explain how passive fire protection contributes to maintaining stability. (4 marks)

Answer 57

Stability relates to the structure of a building and passive fire protections measures are built into this structure to maintain this stability in the event of a fire for a designed period of time. Without these fire protective measures a building could prematurely collapse preventing people from escaping and/or fire services fighting the fire in a timely manner. Structural frames are typically constructed using concrete, timber or steel. All of which require passive fire protection measures to increase their resistance to fire. For example structural elements such as columns can be boxed in with fire rated materials such as gypsum plasterboard. Structural steel will typically sprayed with an intumescent coating, in the event of a fire this will char and expand to provide a protective layer which delays the temperature rise of the steel, as steel will fail at 550 degrees.

Question 58

Identify and briefly describe three different types of fire suppression equipment available within a building. (6 marks)

Answer 58

Gaseous Fire Suppression
Inert gas suppression system
Such systems are designed to suppress a fire by reducing the oxygen concentration to below 15%, where most combustible materials will not burn. Life is sustainable at these levels and healthy people would not notice any adverse effects

Clean chemical gas suppression system
Synthetic or chemical agents are blended man-made gases, which work by absorbing heat rather than oxygen in the form of a cooling mechanism.

Water Suppression Systems
Wet, Dry and Combined Sprinkler Systems. All 3 sprinkler systems use water to suppress a fire. All have a network of pipes that spread throughout a building and are usually activated when an area reaches a certain temperature. Wet systems are constantly filled with water, so water is dispersed instantaneously. Dry systems are used when there is a risk of freezing as the water isn’t constantly in the network of pipes. Combined systems offers the flexibility of both wet and dry, wet usually used during summer months and dry in the winter when at risk of freezing.

Question 59

a) State, with an example, the circumstances when it would be necessary to provide added fire resistance to the concrete frame of a building. (2 marks)

Answer 59

Generally, most concrete frames constructed within the built environment do not require additional passive fire protection measures, as they are designed to achieve a specified fire resistance period. In certain circumstances spalling of the concrete may be considered an issue (for example a road tunnel), in which case additional passive fire protection measures may be required. Only products intended and tested to provide the necessary protection for this type of application should be used.

Question 60

b) Describe how additional fire resistance could be achieved to a concrete frame of a building. (2 marks)

Answer 60

Increasing the thickness of the concrete
Installing additional fire-resistant materials such as gypsum plasterboard.

Question 61

a) Explain what is meant by “section factor” and state the formula. (4 marks)

Answer 61

In relation to steel frame construction, the thickness of the structural fire protection, and the steel configuration to which it will be installed, will determine the length of fire resistance period achieved and will be calculated based on the size and weight of the steel section using a formula known as the ‘Section Factor’ (A/V) where: * A = Surface area of steel exposed to the fire per unit of length * V = Volume of the section per unit length In the past A/V has also been described as Hp/A (heated perimeter of the exposed cross section divided by the total cross-sectional area).

Question 62

b) Explain how section factor affects the required thickness of applied fire protection. (2 marks)

Answer 62

The thicker and heavier a steel section becomes the longer it will take to heat up, therefore the amount of structural fire protection required to control the steel temperature to below the critical level will be less than would be required for a thin lightweight section. Different structural configurations can have the same section factor, but the thickness of the coating will be different.

Question 63

In relation to structural steel, explain the purpose and use of cladding systems made from fire-resisting boards or stone wool products and describe the situations where they may be used. (4 marks)

Answer 63

Cladding systems can be sub divided into six groups:

1. High, medium and low density boards.
2. Blankets
3. Pre-cased
4. Preformed

All of the above systems provide a fire resistance of at least 2 hours and can be upwards of 4 hours.

These products are primarily designed for the use in internal situations and are generally used to box in the steel frame.

Blankets can be installed to follow the contour of a section profile.

Board systems are designed to remain in place without a change in structure throughout the predefined lifespan of the fire by absorbing the heat of the fire to maintain the structural section temperature below that deemed as critical.

Overlapping or abutting different systems needs careful consideration since they may behave in different ways in fire. For example, ‘shrink back’ of any system in fire, at junctions.

Question 64

One of the factors to be taken into account when determining the choice of fire protection system for different purposes is the level of fire rating required. State four other factors that would be taken into account. (4 marks)

8 possible answers

Answer 64

1. Guidance from manufacturers
2. The robustness required
3. Junctions between different fire protection systems
4. Potential future adaptations
5. Correct installation
6. Regulatory requirements
7. Aesthetics
8. Whether it would be subject to environmental exposure such as humidity or temperature changes.

Question 65

Describe the purpose and uses of fire resisting partitions. (6 marks)

Answer 65

A fire wall is a separating element found in various locations throughout a building. A fire wall is designed to restrict the spread of fire for a certain amount of time from one side to the other. They are used to compartmentalise, and sub divide buildings and are also used to enclose areas of special fire hazards and protected escape routes. Fire walls may be incorporated to separate production and storages areas, or to isolate specific areas of production that may be considered a high risk, or simply areas used for different purposes.

Question 66

Describe how timber joist floors behave in fire and explain how this affects the type of fire resistance provided. (4 marks)

Answer 66

Timber joist floors Timber joist floors will char above certain temperatures, the wood will be progressively but predictably consumed by fire. The timber thickness is critical to the structural performance in fire and therefore must be correctly specified. Timber char rate may typically range from 0.5 - 0.8 mm / minute. Fire resistance is usually afforded by a combination of protection to the underside and ensuring there is enough sacrificial timber in the joists. Underside protection will normally be provided by fire resistant board systems such as plasterboard or similar but other systems are available.
Timber floor joists are combustible so will ultimately be consumed by the fire should it progress to a fully developed stage and left to burn.
Examiner Feedback Candidates often provided good responses in relation to the way that wood chars and the use of sacrificial timber. Few referenced the fact that the floor would be ultimately be consumed by fire.

Question 67

Explain the purpose of compartmentation and give two examples of places within a building where this would be found. (4 marks)

Answer 67

Compartment walls and floors are specifically intended to ensure that fire is contained in the compartment of origin and is not allowed to spread horizontally or vertically through a building. Compartmentation is therefore the first line of defence in any fire strategy.
Typical compartments
Escape corridors
Stairwells
Protected lobbies/fire fighting shafts

Question 68

a) Explain the purpose and use of cavity barriers. (3 marks)

Answer 68

Cavity barriers come in three different forms, small cavity barriers, large cavity barriers and open state cavity barriers. There purpose is to close a concealed space in the event of a fire, this could be anything from the cavity wall or a ceiling void. When closed they will prevent the spread of smoke or flames. Cavity barriers are only usually required to have thirty minutes’ integrity and fifteen minutes’ insulation. Open state cavity barriers are usually installed between elements of a building, for example rain screen cladding, where the cavity barrier is open in the cold state to allow for the free movement of air for ventilation. In a fire situation, the cavity barrier closes preventing the spread of fire.

Question 69

b) Describe the difference in use and construction between small cavity barriers and large cavity barriers. (5 marks)

Answer 69

Cavity barriers can be divided into two types:

‘small’ cavity barriers e.g. those used within the leaves of a masonry wall and ‘large’ cavity barriers which can be several metres high/wide which are used to divide large enclosed spaces e.g. in under floor voids and within roof spaces.

Small cavity barriers are usually made from stone wool slabs and strips or preformed elastomeric seals. Large cavity barriers are usually made from either non-combustible fabric such as glass or ceramic cloths or are fabricated e.g. from stone wool curtains.

Cavity barriers are used: around window frames, within cavity walls (masonry and in timber frame constructions) in floor voids e.g. below raised floors, and in ceiling spaces and roof voids. Particular care is required in the installation of some types of cavity barriers e.g. those within cavity walls because they will become inaccessible after installation and so cannot be inspected or maintained.

Question 70

In relation to fire-stopping and sealing systems: a) describe the composition and use of mortars. (4 marks)

Answer 70

Gypsum or cementitious based powder blended with inorganic lightweight fillers, composite reinforcement and chemical modifiers. The compounds are mixed with water and placed around and between penetrating services giving a rigid seal with some products providing a loadbearing seal. It is always important to get the right mix of water and compound particularly for load bearing seals.
The systems can be used to fire-stop penetrations through concrete and masonry compartment wall and floor constructions although some can be used in conjunction with lightweight partitions or timber floors. In certain circumstances, a supporting structure will be required so reference to manufacturers’ instructions is important.

Question 71

b) state two examples of places where mortars would be used. (2 marks)

Answer 71

Loadbearing seal typically used in a service riser.
Service penetrations through a masonry or concrete wall.

Question 72

State two methods for providing fire resistance to a steel duct and give one example of each. (4 marks)

Answer 72

Steel ductwork can either be coated in fire rated paint or not (for example intumescent, ablative or cementitious). Coated with fire rated paint will provide the duct with stability and integrity properties only. In order to provide insulation properties, the steel ductwork will need to be boxed in using fire rated materials such as calcium silicate or vermiculite boards. By applying both of the above will ensure it is fully fire resisting.
Fire dampers are used to prevent fire and smoke spreading from one compartment to another through the ductwork that penetrates walls and floors. Normally, the fire damper is open, but in a fire, it closes. Fire Dampers can be activated by a fusible link or can be intumescent dampers that expand and close the duct when exposed to heat.

Question 73

Describe the purpose and operation of automatic door hold-open/release devices for self closing fire doors. (6 marks)

Answer 73

These devices are designed to hold open self-closing fire doors or allow them to swing free during normal use. In the event of a fire alarm, the device will then release the door automatically, allowing the self-closing mechanism to close the door. Such devices are particularly useful in situations where self-closing doors on escape routes are used regularly by a significant number of people or by people with impaired mobility who may have difficulty in opening the doors.
Automatic door hold-open/release devices fitted to doors protecting escape routes should only be installed in conjunction with an automatic fire detection and warning system incorporating smoke detectors, that is designed to protect the escape routes in the building. In all cases, the automatic device should release the fire-resisting door allowing it to close effectively within its frame (latching securely if a latch is fitted) when any of the following conditions occur:
* The detection of smoke by an automatic detector
* The actuation of the fire detection/alarm system by manual means e.g. operation of break glass call point
* Any failure of the fire detection and alarm system
* Any electrical power failure.
An acoustically-activated door release mechanism complying with BS EN 1155 may be installed in some cases. However, this type of hold-open device is not suitable for use where:
* The premises do not have a fire alarm system
* The door is a fire door serving the only escape staircase in the building (or the only escape staircase serving part of the building)
* The initial fire alarm warning signal is intended to alert staff only
* The fire alarm sounders may be muted, or the sound level reduced
* The fire alarm system incorporates a voice alarm.

Question 74

State the checks that you would carry out when completing the installation of fire and smoke seals on fire doors. (6 marks)

Answer 74

• Check they are in good condition
• Full length and secure in the groove
• If seals are badly finished, damaged or painted over then they must be replaced with exactly the same size and intumescent material that was originally specified
• If the smoke seals have been replaced, they should be fitted in one continuous length if possible
  Check manufacturers instructions.
  Check that there are no gaps around ironmongery
  Ensure the perimeter gaps are less than 3mm
  Don’t use more than one product on the same door as they will react differently.

Question 75

In relation to the fire tetrahedron, explain how water and dry chemical powders work to extinguish fire. (4 marks)

Answer 75

Water can be used to lower the temperature of the fuel below the ignition point or to remove or disperse the fuel. Water can be applied to a fire by a fire extinguisher by a competent person or via sprinkler system.
Dry chemical powder extinguishers can be applied to a number of different fires such as those involving flammable liquids, flammable gases, fires involving electrical equipment and typical fires that include wood, textiles and paper etc. They work by starving the fuel of the fire from oxygen, they do not cool the heat of the fire and therefore there is a risk of reignition.

Question 76

Describe the process of smouldering combustion. (4 marks)

Answer 76

Some fires start off as smouldering hot spots. These fires do not grow very quickly and do not produce very much heat but can produce very toxic smoke. Smouldering fires may suddenly turn into real flaming fires and grow very rapidly. They are particularly dangerous in fires where people may be asleep, e.g. a hotel
to burn slowly with smoke but without flames: a smouldering fire.

Question 77

In relation to means of escape, explain what is meant by the following terms: a) “evacuation time” (2 marks)

Answer 77

Evacuation time refers to the period of time it takes for building occupants to react to the presence of fire/sounding of the fire alarm and evacuate to a place of relative safety or absolute safety.

Question 78

In relation to means of escape, explain what is meant by the following terms:
a) “evacuation time” (2 marks)
b) “travel distance” (2 marks)

Answer 78

The travel distance should be measured from the farthest point in a room to the door leading to a protected stairway or, if there is no protected stairway, to the final exit of the building. Government guidelines state that, if there is only one escape route, the travel distance should not be more than 18 metres. The distance people have to go to escape (the travel distance) must be as short as possible. The travel distance needs to factor in the layout of the building including internal walls and any fittings that will increase the travel distance to bypass these obstructions.

Question 79

Explain how the use of fire retardants contributes to passive fire protection in a building. (4 marks)

Answer 79

The surface of a construction product can be treated with a ‘fire retardant’ system to minimise any damage from a small fire that’s trying to grow and become bigger.

The intent is to stop a fire growing or spreading to unmanageable proportions.

Timber is a great example of where fire retardants can be applied to improve the passive fire protection in a building. Applied as a coating or treated offsite before installation both techniques significantly reduce the rate at which fire can spread.

Coatings can be ablative or intumescent, intumescent expand and provide a protective layer known as char which insulates the timber from both heat and oxygen therefore controlling the fire. Ablative coatings give off gases and vapors that disrupt the chemistry of the fire.

Question 80

In relation to fire resistance, explain the term “insulation” and explain why this is important. (4 marks)

Answer 80

The fire insulation properties protect the unexposed face of a compartment, i.e. the other side of a compartment wall to where the fire is burning, should not increase in temperature above an average of 140°C or by more than 180°C at any one point. This requirement is to ensure that anything of a combustible nature that might be close to or touching the compartment wall cannot be ignited due to the transfer of radiant heat generated through the compartment. Note: This is why fire doors in the UK are not usually required to be insulating because there will not be combustible items stored against them.

Question 81

Explain how signage can be used to improve fire safety in a building. (4 marks)

5 sign types

Answer 81

Signage is crucial to improving fire safety in a building. Typically there are multiple types of signage and all will contribute. Five Types below:

For example, safe condition signs should be installed throughout the building, these will be green and will provide information on fire exit locations etc.

Prohibition signs should also be installed for example no smoking signs will warn people not to smoke and in turn improve fire safety as this will eliminate this risk.

Warning signs will notify building occupants of any specific risks, these could be risks that directly contribute to a fire.

Mandatory signs and fire fighting signs will provide building occupants with information of what to do in the event of a fire and provide locations of any portable fire fighting equipment such as fire extinguishers.

Consideration should be given to emergency lighting or use of illuminated signs to improve fire safety as building occupants will be able to see the signs should there be a power failure.

Question 82

State the three main types of intumescent coatings used on steel structural designs and give an example of a situation where each would be used. (6 marks)

Answer 82

Solvent borne - thin film
Water borne - thin film
Epoxy - thick film

Solvent based coatings
Would typically be used on most steel frame structures/buildings as it can offer protection to the stability of the building for 60 minutes and upwards of 90 minutes or 2 hours depending on the section factor.

Thick Film Coatings
Epoxy paint would typically be used on steels that would likely be affected by hydrocarbon fires, the thicker film system chars at a slower rate and only expands up to five times its original thickness, however it can withstand higher temperatures that would be caused by the hydrocarbons or jet fires.

Solvent/ water based
Thin filmcoating systemstend to be either solvent- or water-based and can be used forfire protectioninbuildingswithresistancerequirements of 30, 60 and 90 minutes. They usually consist of threelayers:
Primer.
Basecoat (the reactivecomponent).
Sealer coat.

The typicalexpansionratio of a thin film is 50:1, meaning that acoating1 mm thick will expand to approximately 50 mm when in contact withfire. The advantages of thin film are that both solvent and water-basedcoatingscan achieve decorative and bespokesurface finishes and can easilycovercomplexshapes.
Thick filmcoatingssystemstend to be epoxy-based and have been modified for use inbuildingshaving originally been developed foroffshoreandhydrocarbonindustry applications where thetestheatingprocess is more stringent than that forindustrialandcommercialapplications. The typicalexpansionratio is much lower than thin film, usually 5:1.

Question 83

Describe the inspection processes to be applied during the installation of board systems. (6 marks)

(7 bullet points)

Answer 83

1. You would ensure that the board system provides the correct level of fire resistance.
2. You would ensure the system is installed as per the manufacturers guidance/tested detail.
3. Ensure the correct number of mechanical fixings have been used and positioned correctly.
4. Ensure the correct fixings have been used as these will vary from manufacturer to manufacturer.
5. Ensure the correct thickness
6. Ensure the steel is fully enclosed when boxing in.
7. Inspect what type of material has been used whether it be stone wool, vermiculite or calcium silicate etc.

Question 84

Describe how composite floors are constructed and explain how this effects how they behave in fire. (4 marks)

Answer 84

Composite floors generally consist of a profiled metal deck with a poured concrete topping which can perform differently in fire, because the metal base will conduct heat from fire laterally, and in so doing the metal face will attempt to expand. The rate of temperature increase in the critical parts of the floor may be lessened compared to concrete alone, however the composite floor will also be fixed through shear connectors to the supporting steel structure. During the fire, steam formed in the concrete may force out the metal decking, distorting it and causing gaps and subsequent failure, and whilst the steel reinforcement will transfer the load and the heat from fire, the composite structure may ultimately deform under the heat and sag under the load of the concrete.

Question 85

Explain why active fire curtains may be used to provide compartmentation and give two examples of locations where they may be used. (4 marks)

Answer 85

They provide flexible compartmentation and allow designers to create open spaces such as atriums. As more and more buildings are designed to have open plan spaces there are a lack of walls to compartmentalise buildings, therefore active fire curtains can be used as an alternative to fire suppression systems. Active fire curtain barriers are normally used to provide compartmentation and to protect means of escape and may be installed in any type of building where these are required. Typical applications include:
Atriums
Lobbies and receptions
Boundary protection (external)
Openings in walls
Compartmentation
Stair wells
Lifts
Escalators

Question 86

a) Define “active fire curtain” and state the purpose of active fire curtains. (2 marks)

Answer 86

Active Fire Curtain Barrier Assemblies generally comprise of a fire-resistant fabric barrier encased in a compact steel housing. Such barriers remain out of sight in a retracted state until activated by an alarm or detector signal, at which time they descend safely to their fire operational position.
Active fire curtain barrier systems are used to form either compartments or protected routes and can be used as alternatives to traditional methods of construction such as non-loadbearing walls, ceiling, fire doorsets, or glazing systems. Active fire curtain barrier systems may also be used in a strategy to provide flexible compartmentation when the alternative might be to use fire suppression system.

Question 87

a) Explain the purpose of compartmentation. (2 marks)

Answer 87

Stop small fires becoming big fires
Limit the fire to the compartment of origin
Protect means of escape

Question 88

b) Describe four factors to be taken into account when determining and installing fire protection for compartment walls. (4 marks)

Answer 88

The construction of the wall and whether it is load bearing or not
The fire rating of the wall whether it needs to be 30, 60 or higher
Manufacturers guidance and instructions to be reviewed and adhered to
The aesthetics, what the the fire protection measure is going to look like

Question 89

a) Describe how non-fire rated glass behaves in fire. (2 marks)

Answer 89

Non fire rated glass will typically fail below 100 degrees. Therefore when a fire breaks out non fire rated glass will quickly crack and fall out of its frame. This situation can be amplified if the thermal shock generated by water from a firefighters hose or the activation of a sprinkler system were to impinge the hot surface of the glass. Furthermore, in situations where security is deemed a critical issue, toughened (also known as tempered) glass will often be considered appropriate. However, in fire conditions such glazing is subject to catastrophic failure.

Question 90

b) Explain what is meant by “integrity only glazing” and give two examples of this type of glass. (3 marks)

Answer 90

Sometimes referred to as ‘fire protective’ glazing, such glazing systems are designed to hold back flames, hot gases and smoke within the compartment of origin for a defined period of time, typically 20 – 180 minutes. Although 20 minutes is listed in building regulations this is not normally accepted in practice. This type of glazing can be based on a number of different technologies, which include:
* Wired glass
* Laminated float glass with intumescent or char promoting interlayers
* Modified toughened glass
* Borosilicate glass
* Glass ceramic
* Those using various types of non-insulating organic interlayer technology

Question 91

Describe open cavity barriers and state two locations where they would be used. (4 marks)

Answer 91

Open cavity barriers such as those used in rain screen cladding systems are cavity barriers which are open to allow ventilation and drainage in the cold state, but which either close in a fire, or are inherently fire resisting providing fire separation in the cavity. They are usually made from stone wool slabs faced with aluminium foil together with a reactive component such as an intumescent which causes the seal to close in fire.

Areas of Use
Open cavity barriers are used in:
1. ventilated rain screen cladding
2. roof ventilation,
3. eaves,
4. within internal walls in buildings and other areas where ventilation is required in the cold state.

As with ordinary sealed cavity barriers, they are not normally intended to act as fire separating elements which have higher requirements for fire resistance. Although this should be checked at site. Particular care is required in the installation of some open cavity barriers as these are normally difficult to access after installation.

Question 92

Describe the factors to be taken into account when selecting and installing penetration seals (4 marks)

6 points

Answer 92

Whether there is a manufacturers tested detail states it can be used on that particular penetration seal.

What level of fire resistance period it needs to achieve.

If the penetration seal is visible you may need to consider the aesthetics, for example if it is below ceiling.

Ensure the penetration seal is tagged appropriately.

What is the substrate of the wall, masonry, concrete, plasterboard.

Is access an issue can the penetration be reached safely.

Question 93

Describe the composition and use of sealants/mastics. (5 marks)

Answer 93

Sealant or mastic are typically made from silicone or acrylic and are applied by a mastic gun or trowel applied into an opening and between/around suitable penetrating services.

They may be used to seal around any penetrating services where testing indicates their suitability.

They are also suitable when used in conjunction with coated batts/boards in all forms of fire resistant construction, where openings are small, where penetrations are complex and where there is imperfection of fit between building elements.

High pressure exerting sealants are installed into an oversize aperture in the separating element, surrounding the penetrating service. If there is a fire risk on both sides of a compartment wall or floor, HPE sealant may be required on both sides, the high pressure exerting sealant is installed to a prescribed annular gap to a predetermined depth between the service penetration and the constructing element. The backing material for these sealants should be checked before use to ensure they are approved. High pressure exerting sealants tested in a rigid wall may not work when tested in a flexible wall without suitable framing out, although some manufacturers do have test data for this type of application.

Specifiers and installers should check that the supporting fire test evidence is applicable for the end use application envisaged.

Question 94

Stone wool mineral products are supplied in a number of forms when used as firestopping. State the forms that such products take and state the factors to take into account when installing these products. (3 marks)

(7 possible forms)

Answer 94

Stone wool fire batt, matts and preformed shapes

Insulated fire sleeves

Small cavity barriers

Stone wool fire curtains

Fire protection boards

Stone wool wraps

Stone wool core doors

Whether they are the appropriate product to be used for that particular service penetration. Manufacturers guidance and tested details should be considered.

Question 95

In relation to the construction and design of the building envelope, describe how the use of cladding can affect fire resistance. (3 marks)

Answer 95

Cladding systems may be specifically designed for new buildings or they could be retrofitted to an existing building for improved aesthetics, weather protection or improved thermal insulation.

Rainscreen cladding systems will have gaps to allow for ventilation these gaps will provide a route for the fire to travel if no open cavity barriers are installed.

Cladding could serve to increase the fire load if not constructed out of fire-resistant materials.

If the cladding is poorly fitted there may be gaps which reduce the integrity.

There have been instances in buildings where a fire has broken out on one floor and the external window has failed allowing the cladding to catch fire, this cladding then spreads vertically and potentially entering the building on another level when the glazing fails on the floor above.

Examiner Feedback Many candidates appeared to misread or misunderstand this question. Many candidates were unsure about cladding. A few candidates provided the specification for cladding but did not answer the question. Many candidates stated that cladding must be fire resistant, the question asked to describe how the use of cladding can affect fire resistance i.e. poorly fitted. Gaps providing a route for fire to travel, and cladding can increase fire load.

Question 96

Describe the checks that you would carry out when inspecting the installation of ironmongery fixed to fire doors. (6 marks)

8 points listed

Answer 96

I would check that the fire door has the appropriate number of hinges (3 minimum)

I would ensure it is fitted with a self closing device if required for example a service riser door will not require a self closer as this should be locked when not in use.

If a letter box is installed I would check that this formed part of the original door and is not a later addition, this will need to have additional fire resistance built in to ensure the gap doesn’t allow the passage of fire and smoke.

If the door has a latch I would check that the door latches when self closing.

I would ensure all ironmongery is CE approved.

Check that all ironmongery components are applicable to that door assembly and are in line with door certification.

Check the general condition of all ironmongery.

Check that the door closer is closing in a timely manner and doesn’t slam shut.

Examiner Feedback This question was poorly answered with many candidates only scoring 1-2 marks. Many candidates tried to guess answers for this question. Many candidates failed to stated that fire doors should have a minimum of 3 hinges, are fitted with a self-closing device. Very few candidates mentioned that letter boxes should have additional fire resistance built into them to prevent fire spread or arson attacks

Question 97

Internal compartmentation and fire resisting construction are examples of passive fire protection.

B) Explain the role of passive fire protection when considering the approach to fire safety design. (2 marks)

Answer 97

B) passive fire protection is used to separate a building into fire resistant compartments to prevent the passage of fire and smoke around a building for a specified period of time. ( the fire resistance period)
Protect the means of escape
Protect access corridors in order to aid fire fighting
Insulate the fabric of the building, in particular the loadbearing elements from the effect of fire in order to maintain structural stability for the specified period of fire resistance

Question 98

In relation to fire development, explain what is meant by the term “flashover”. (4 marks)

Answer 98

As the fire grows, a hot smoke layer at the ceiling of the room grows in depth, effectively trapped by the walls of the compartment. The radiated heat from this layer rapidly heats the surfaces of those combustible materials directly exposed in the room, causing them to emit flammable gases. When the temperatures of the evolved gases become high enough (circa 600 degrees), these gases will ignite throughout the smoke layer. This almost instantaneous event is known as flashover and is characterised by a very rapid rise in temperature and the involvement of all combustible materials in the room.

Question 99

Identify two toxic gases that can be generated during fires and explain the effects of toxic gases on human health. (4 marks)

Answer 99

Carbon Monoxide
The most common of these, carbon monoxide (CO), can be fatal, even in small quantities, as it irreversibly replaces oxygen in the bloodstream.

Hydrogen cyanide
Hydrogen cyanide generated from the burning of plastics, can interfere with cellular respiration.
Examiner Feedback Some candidates failed to identify two toxic gases and this meant that they were unable to attain the two marks allocated for the identification of such gases. Gases that could have been mentioned included carbon monoxide (CO) and hydrogen cyanide.

Question 100

a) In relation to building materials, explain what is meant by the term “reaction to fire.” (1 mark)

Answer 100

Reaction to fire is the degree to which a material may contribute to the growth of a fire.

Question 101

b) Identify three factors that can be used in measuring how a material reacts to fire. (3 marks)

List of 5

Answer 101

reaction to fire is the degree to which a material may contribute to the growth of a fire.

The five contributing factors are:

• Ignition,
• Combustibility,
• Spread of flame over a surface,
• Release heat (rate of/fire propagation)
• Production of flaming droplets and smoke.

Examiner Feedback Many candidates appeared to be unfamiliar with the technical definition of “reaction to fire” and appeared to make up an answer. Good responses explained that reaction to fire is the degree to which a material may contribute to the growth of a fire. Factors that could have been identified in response to part b) were ignition, combustibility, spread of flame over a surface, release heat (rate of/fire propagation) and production of flaming droplets and smoke.

Question 102

In terms of product testing, assessment and certification, explain the following: a) Certification from a Third-Party Certification Body.(4 marks)

Answer 102

Third-party certification means that an independent organization has reviewed the manufacturing process of a product and has independently determined that the final product complies with specific standards for safety, quality or performance.

An independent assessment is undertaken by a Certification Body, themselves accredited by the United Kingdom Accreditation Service (UKAS in the UK), declaring that specified requirements pertaining to a product, person, process or management system have been met.

Third-party certification body will consider the testing and assessment data supplied but in addition will also:

Evaluate performance from a range of tests (not just a single test) and use these to create a scope of certification which covers the complete product range

Access evidence from tests used in assessments to create a scope of certification to cover performance of product range

Undertake factory production control audits / inspections of production of the products, typically these will be conducted annually.

Require the manufacturer to declare changes to products.

Require manufacturer to label products sold to aid traceability in case there are any problems.

Undertake ongoing product verification (audit tests / inspections) at predetermined frequencies

Question 103

In terms of product testing, assessment and certification, explain the following: b) an assessment from an accredited fire test laboratory or suitably qualified fire consultant. (4 marks)

Answer 103

This is the second tier of evidence used to support manufacturers’ products in the market. This level of assessment will offer some of the process required to achieve third-party certification, such as an evaluation of performance from range of tests (not just a single test), and an assessment of evidence from tests to enable a ‘field of application’ to be determined. It is the next best thing to third party certification but offers none of the quality control aspects.

Used as a means to verify both use and limitations of use. It is however important to ensure that those offering the ‘Assessment’ are qualified to make such a judgement and can demonstrate their competency to do so.

Examiner Feedback Few candidates scored high marks for this question and it appeared that few were familiar with the methods of product testing. The two methods were often confused by candidates and many were unable to draw out the differences between them.

Question 104

a) Explain how the thickness of a steel structure affects its fire resistance and the amount of structural fire protection required. (2 marks)

Answer 104

The thickness of steel affects the fire resistance because the thicker the steel the longer it takes to heat up to a critical temperature of 550 degrees. The section factor of steel is used to determine the thickness of intumescent coatings to improve the fire protection. The section factor is A/V

Question 105

b) Explain, using examples, how the shape of a steel structure can affect the performance of fire protection systems. (3 marks)

Answer 105

The shape of the steel structure can affect the performance of fire protection systems because the intumescent coating will insulate less well on some sections, for example a circular hollow section. As the char expands it may crack due to the circular nature, these cracks will then allow the heat to reach the steel.

Question 106

Describe fire-resisting suspended ceilings and describe the materials from which they are usually constructed. (5 marks)

Answer 106

A fire resisting ceiling may be defined as an interior surface that covers the upper limits of a room, and generally is not considered a structural element, but a finished surface concealing the underside of the roof structure or the floor of a storey above. Typically, such ceilings are suspended from the structural elements above, to enable pipework or ducts to be run in the gap above the ceiling. Such ceilings are generally constructed from gypsum, stone wool or calcium silicate-based products supported on a lightweight steel framework.

Question 107

Describe the purpose of a pressurisation ductwork system and explain the considerations in determining protection for this ductwork when penetrating fire resisting barriers. (5 marks)

Answer 107

Pressurisation is a method of restricting the penetration of smoke into certain critical areas of a building by maintaining the air within the critical areas at pressures higher or lower than those in adjacent areas. It applies particularly to protected lobbies and corridors, as smoke within these areas would inhibit escape, and also to firefighting shafts serving deep basements, because of the difficulties in clearing smoke from basements. A pressurisation system is a form of mechanical ventilation system. As the air supply creating the pressurisation must be maintained for the duration of a fire, fire dampers cannot be used within the ductwork to prevent the spread of fire. Any duct penetrating fire resisting barriers must be fire resisting.

Question 108

Explain the purpose of air transfer grills in fire doors and explain how these would operate in a fire situation. (4 marks)

Answer 108

In normal use, air transfer grills allow air to be circulated and moved throughout the building, however during a fire such grills are designed to close and provide a fire barrier to restrict the passage of fire and hot gases. Such grills may be constructed with an intumescent component that will expand under fire to restrict fire and hot gases, however such systems will not prevent the passage of cold smoke. In such situations, for example a fire door protecting a means of escape, the air transfer grille will also need to be of a type that can be linked to a suitable fire detection/alarm system to enable the grille to close thereby inhibiting the passage of cold smoke.

Question 109

Describe four checks that would be carried out prior to installing the door frame for a fire door. (4 marks)

7 answers possible

Answer 109

The door frame should be free from damage.

It should be suitable for the required fire rating.

Should be compatible with the door assembly/doorset.

BWF-Certificate label/s on frame (if applicable) undamaged.

Check if relevant instructions for fitting are available.

Ensure competent/trained staff are employed to carry out the fitting.

Check the frame is suitable for the construction installation (masonry wall etc.)

Question 110

b) Describe the factors to be taken into account when selecting an active fire curtain for installation. (4 marks)

6 possible pointd

Answer 110

The following should be considered when selecting an active fire curtain:

Whether the active fire curtain needs to be used in a horizontal, vertical or inclined orientation

Whether the purpose is to provide compartmentation or to protect the means of escape.

What the required fire resistance period is

The size of the fire curtain

How many motors are required to ensure the curtain operates successfully.

Whether or not there is a compliant fire alarm to operate the fire curtain.

Question 111

What are the factors that effect fire resistance requirements

5 points - ASFP question

Answer 111

Purpose group - the type and use of the building e.g. Offices

Evacuation strategy

Building location

Provision of active fire suppression systems - the use of fire suppression systems can be justification for reduction on passive fire protection

Height above ground

Question 112

What are the considerations with respect to compartment size

3 points - ASFP

Answer 112

Whether there is a sprinkler system

Purpose group

Heigh above ground