Option 2: Fire resisting walls, floors and ceilings and fire resistant glazing Flashcards
Describe the purpose and use of compartment walls. (6 marks)
The purpose of compartmentation is to contain a fire within the compartment of origin for a given period of time. Compartmentation allows safe evacuation, encloses areas of high hazards, prevent financial losses
a) State two factors to be taken into account when determining the degree of fire resistance
required roof compartment walls. (2 marks)
b) State four locations in a building where compartmentation would be installed. (4 marks)
A
Compartmentation fire performance
The degree of fire resistance required will depend on several factors including:
* The specified fire resistance period
* The height of the top floor above ground and the intended use known as the purpose group
of the building
* Whether fire resistance is expected from one side or both sides of the barrier
* The type of fire performance required i.e. stability, integrity and insulation
B
Between Different Occupancies – To separate areas with different uses, such as residential and commercial spaces in a mixed-use building, to prevent fire spread between them.
Stairwells and Escape Routes – To protect exit routes, ensuring safe evacuation by preventing fire and smoke from spreading into these critical areas.
Plant Rooms and Service Areas – To contain potential fires in high-risk areas like boiler rooms, electrical rooms, and generator spaces.
Basements and Parking Garages – To prevent fire from spreading to upper floors and to contain fires in areas with high fire loads, such as vehicles and stored materials.
Describe how composite floors are constructed and explain how this affects how they
behave in fire. (4 marks)
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.
Describe the purpose of active fire curtain barriers and state two places where active fire
curtain barriers may be found. (4 marks)
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.
Active Fire Curtains typically comprise a fire-resistant fabric wound onto a roller enclosed within a head
box fixed above the opening to be protected. They are usually powered by an electric motor. A weighted
bar is fitted to the bottom edge of the fabric curtain and each side is retained within a vertical channel
which is fixed to the sides of the opening to be protected. The electric motor is connected via a power
supply to a control panel which is in turn connected to a local detector or fire alarm panel. Deployment of
the Fire Curtain is usually initiated by the fire alarm but shall fail-safe by gravity.
Found in
- Atriums
- Lobbies and receptions
- Boundary protection (external)
- Openings in walls
- Compartmentation
- Stair wells
- Lifts
- Escalators
Describe each of the following types of glass and state how each behaves in fire including
the type of fire resistance provided:
a) Wired glass (3 marks)
b) Laminated composite (3 marks)
Wired Glass
Wire mesh glass, sometimes referred to as Georgian wired glass, is the oldest form of fire resisting
glazing systems available, formulated with a grid or mesh of thin metal, wire embedded within the
glass in the manufacturing process.
The wire prevents the glass from falling out of the frame even if it cracks under thermal stress, and
applications include visual panels within fire doors, as screens, overhead glazing and fanlights. Such
glazing can maintain integrity when subject to thermal shock, i.e. when sprayed with water.
Laminated composites combining a hard intumescent interlayer between annealed glass
Typically, this glazing system is formed with a sodium silicate based interlayer, which in the event of a
fire will turn opaque and swell, and in the process will ensure that, as the glass layers crack, they will
remain bonded to the interlayer.
This is a progressive process depending on the number of sheets of glass and interlayers bonded
together, which enables this system to offer extended fire insulation performance.
Identify four factors to be considered when glass is supported by a timber framing
Timber glazing systems
* Type of glass: Integrity only, partial or fully Insulating
* Type and density of timber
* Size of sections and cross-section dimensions of frame
* Depth of glazing rebate
* Size, shape and design of glazing beads
* Type of fixings of the beads, their location and angle of fixing relative to the type of glass
* Edge cover and clearances for the different types of fire-resisting glass (especially for modified
soda-lime silicate toughened glass)
* Type of glazing seal
* Nature of any timber treatment required
* Compatibility of all components
* Method and materials used to fix the frame to the surrounding structure, e.g. walls
* Fire stopping between the fire-resistant screen or door frame and wall
* Internal or external position
* Requirements for doors within screens
* Availability of fire test or third party assessment evidence to support detailed specification
* Installers capability regarding fire-resistant glazing and availability of trained and certified
personnel
