Construction Tech Flashcards
What is Radon?
◼ Colourless, odourless, radioactive gas
◼ Poses a risk to health in high concentrations e.g. builds up in enclosed spaces such
◼ as basements
◼ Health Protection Agency — published a map of radon affected areas in the UK
◼ Passive monitors and detectors should be installed in homes in affected areas and
◼ tested for a period of 3 months
◼ Remedies include;
◼ Prevent radon entering a building by altering the pressure balance between inside
and outside
◼ Sump pump below floor and connected to a fan Improve ventilation in suspended
floors
◼ Install a fan in the roof space
◼ Install a membrane barrier — seal all ducts, joints, cracks in building
◼ Governed by Building Regulations Approved Document C
What is the external envelope?
The materials and components that form the external shell or enclosure of a building
May be load or non-load bearing
What are retaining walls?
They act as an earth retaining structure for the whole or part of their heights
Need to consider water pressure and pressure of the retained earth in their design
What is single lap tiling?
Typically, tiles utilise a ‘tongue and groove’ detail to maintain weather
tightness. Lighter construction but requires larger roofing battens and
mechanically fixed every 2nd course.
Can be used on shallow pitches.
What are the technical disadvantages of concrete frames?
More time consuming. Slower to construct
Edges may not be as square and surfaces not as flat as steel
The need for steel reinforcement leads to some of the cost issues associated with
steel
Heavier so requires larger foundations
What colour pipes are building services?
− Yellow Pipes (Gas)
− Blue Pipes (Water)
− Brown / Grey Pipes (Drainage)
What is Type A Tanking?
- Continuous waterproof membrane applied to slab and walls (internally or
externally)
External best as it protects against sulphate attack
External cannot be applied retrospectively
Mastic asphalt traditionally used but polymers now available
How many bricks are in a m2?
There are about 60 bricks per m2.
What are international standards?
Prepared by the International Organisation for Standardisation – prefixed ISO
Compatible with and complement BS’s
What is Legionnaires disease?
• Legionella is an aquatic organism (bacteria)
• Most prevalent at 40-65% relative humidity - the perfect comfort level for people
• Can be vaporised from showers and humidifiers and be inhaled causing
Legionella Pneumonia
• Legionella Pneumonia can be fatal!
Where would you go to find out if a material was banned from use in
construction?
British Standard Online – British Standards Specification
How is water provided for a sprinkler system?
From the mains
A pumped Supply
A pressurised supply
What is the size of a brick?
Standard bricks are 215mm x 102.5mm x 65mm
Tell me more about soil investigations?
Purpose is to determine the suitability of the site for the proposed works and
determine adequate and economic foundation design
Should determine the potential difficulties
The method chosen will depend on type of building – function, size etc
What are the main site considerations?
Access considerations – approach roads etc Storage considerations Accommodation Temporary services Plant Fencing / hoarding Safety and health
What is bottom up construction?
“Bottom up” forms the basement and then works upwards in a traditional manner.
Simpler but a longer programme.
What are the main components of a hipped end pitched timber roof
structure?
Principle Rafters – Provides support to roof covering. Span from eaves to ridge
Jack Rafters – Shorter rafters that run from hip to eaves or ridge to valley
Ridge board – Spine of roof carcass than runs along the ridge
Hip rafters – where two roof surfaces meet to form external angle
Valley rafter – where two roof surfaces meet to form internal angle
Bargeboards / fascia – to cover feet of rafters
Purlins – Intermediate horizontal members to support rafters
Battens – small pieces of wood to which the roof covering is affixed
Covering – either laid or fixed on to a roof to protect from the elements. Types used
are:
Slates – interlocking or plain
Pan tiles – burnt interlocking clay tile into an ‘S’ shape (Mediterranean style).
Zinc
Copper
Thatch
Wall plates – to receive the feet of rafters at top of external wall
What is a basement?
A storey below the ground storey
What are the different types of brick bond?
Stretcher – most common, walls just a half brick wide
English – alternating courses of headers and stretchers
What are panellised systems?
• Like unitised systems, panellised curtain walling is constructed in the
factory to improve quality control and speed of erection. However, the
systems comprise large prefabricated panels of bay width and storey
height, which are connected back to the primary structural columns or to
the floor slabs. Panels may be of precast concrete or comprise a structural
steel framework and are often clad with a variety of stone, metal and
masonry cladding materials.
• The advantage of these systems is improved adherence to specification as a
consequence of factory prefabrication, allowing improved control of quality
and rapid installation with the minimum number of site sealed joints.
Panellised systems are less common and more expensive than unitised
construction.
What is slip forming?
A method for constructing a repetitive structure such as a core, lift shaft or stairwell.
The formwork is constantly moving upwards, approx. 1” every 10mins.
The concrete that becomes exposed must be cured enough to support.
What is the difference between rolled and tiled carpet tiles and why do
we use each type?
Rolled carpets generally better quality and more expensive. Used in dwellings.
Carpet tiles – harder wearing, lower quality cheaper and individual tiles can be
replaced therefore easier to maintain. Used in offices, hospitals etc. Also where
raised flooring systems are used carpet tiles allow for easier access to services that
run in the void below.
What are piles?
A series of columns constructed or inserted into the ground to transmit the load of a
structure to a lower level of subsoil
Used where no suitable foundations conditions near ground level or high water table
Name some types of shallow foundations?
- Pad
- Traditional Strip / ground beams
- Solid Slab Raft
- Deep Strip / Trench fill
Detail an inverted Roof?
• A roof in which the insulation is placed on top of the waterproof membrane.
• No vapour control is needed.
• Roof void and or deck are maintained at similar temperature to the room.
• The insulation protects the membrane from damage but must
be anchored down.
What would you consider when selecting the type of pile to use?
Use - Point Load from frame, Retaining Wall, Basement, Sheet pile to strengthen
embankment
Cost
Depth of piles
Contractors experience of difficult sites
Ability to complete works in a phased programme
Cost of extensive testing
Type of soil (displacement / replacement piles)
What is settlement?
◼ All new structures settle following construction
◼ Extensions may settle differently to older parts which have already settled. This
needs to be accounted for in the design e.g. suitable foundations, expansion joints
What are the technical advantages of concrete frames?
Examining the impact of the steel price rises has found that the whole project costs
for concrete framed buildings are marginally less than for steel framed buildings.
Fire protection as part of structure
Slower form of construction at this early stage will reduce the cash flow early on
Maintenance of an insitu concrete frame is low
Cladding can be fixed to it and replaced easily.
It also provides good sound and heat insulation.
Insitu allows for alteration at late stage of construction
Can deal with complex geometry better than steelwork
What is subsidence and wjat are the signs?
• A symptom of when; the loads applied exceed the bearing capacity of the ground,
or;
• Loss of support beneath the foundations (insufficient foundations, leaking drainage
causing erosion, trees taking up moisture in clay or dry periods of no rainfall, old
mines)
• Distortion / movement of the roof covering / dip in the roof ridge Dropped heads to
door and window openings, openings not square (binding)
• Cracking will pass through DPC
• Shear cracking is vertical movement,
• Tapered if rotational
• Tapered cracks are wider at the top than the bottom
Sketch an eaves detail of a typical warm pitched roof and name the elements.
…
What is inert & active waste?
Inert - aggregates /soil / stone / brick / concrete / plaster / glass.
Active - Timber / paint / demolition waste. “
What is a Remediation Notice (served by the LA)?
◼ Local Authority will first issue a notice for the owner / occupier to rectify
◼ After 3 months a Remediation Notice can be served
◼ Sets out the scheme proposed, any exclusions from liability and apportionment of
costs
◼ Notice can be appealed within 21 days if there is an error in the Notice,
timeframes are not adhered to or incorrect person has been contacted
- Class A person — known polluter
- Class B person — polluter unknown, so current landowner or occupier
What is the difference between bored/pre-cast piles? What are the
problems to the PQS regarding cost control with piling? Whose risk
is the piling?
Bored piles are defined when the process for removing the spoil to form the hole for
the pile is carried out by a boring technique. They are used primarily in cohesive
subsoils for the formation of friction piles and when forming pile foundations close to
existing buildings where the allowable amount of noise and/or vibration is limited.
Pre-cast Concrete piles are generally used where soft soil deposits overlie firmer
strata. These piles are usually driven using a drop or single action hammer.
What is scabbling?
Scabbling utilizes piston driven carbide tipped heads which impact the surface at a
rapid rate pulverizing concrete or brittle coatings. Scabbling can be very effective in
the removal of slightly bonded coatings or where the coatings are impossible to be
removed by the shot blasting process. It can also remove level inconsistencies in
concrete floors
When would you need to use piles?
1) Low bearing capacity of subsoils
2) Heavy point loads of structure exceed bearing capacity of soil
3) Presence of highly compressible soils near surface such as peat
4) Subsoils such as clay which are prone to movement
5) High water table”
Detail a cold roof?
• Insulation located at ceiling level
• Void or roof slab is insulated from heat loss from below and is therefore at a
colder temperature than the room during cold weather.
• Risk of condensation forming within the roof void or on the underside of
the slab, so good cross-ventilation is essential.
• Vapour control layers at ceiling level are essential, but not 100% effective.
What are hoists?
Design for the vertical transportation of materials or people
What fire safety provisions would you expect to find in an office
block?
Maximum occupancy listing (Making sure that an area isn’t so full of people that they
can’t all get out quickly in an emergency).
Fire exits and proper signage of them (e.g., Exit signs pointing to them that can
function in a power failure)
Placing fire extinguishers and fire alarms in easily accessible places.
Banning of over-flammable materials for building or use.
Frequently inspecting public buildings for violations and closing it until the violation is
corrected or condemn it in extreme cases.
Installing fire alarm control panels for quick detection and warning of fire
What is a strip foundation?
Suitable for most subsoils and a light structural design, usually reinforced
Detail reinforcement requirements for concrete floors?
• Steel reinforcement can be in-situ or pre-cast
• Typically, pre-stressed to provide tensile strength
• Minimum of 20 mm — 70 mm concrete cover is required to prevent corrosion
and provide fire protection.
• Comply with BS 8110 — Structural Use of Concrete
Name some of the main materials that have been banned from use in
construction?
High alumina cement in structural elements
Asbestos
Urea formaldehyde.
ACM cladding
Draw a typical trussed roof structure.
…
What is Type B Tanking?
Waterproof construction - Monolithic Concrete Walls and Floors
Dense high-quality reinforced concrete
Relies on good materials and workmanship (attention to detail)
Not always water / vapour proof
Not suitable for living / archiving areas
Risk of sulphate attack
What are British Standards?
Publications issued by the British Standards Institution – prefixed BS
They give recommended min standards for materials, components, design and
construction practices
What are the different types of piles?
Sheet piles – a deep trench is excavated and concrete is poured in situ. The piles
can be used to form basement walls or act as retaining walls.
Secant piles – interlocking piles (male and female, often different diameters and
hardness) are bored to provide a combination of foundations and basement walls.
They go someway in providing a waterproof structure. Secant piles are often seen
when a top down construction method is used.
Bored Piles – an auger is used to excavate the soil and then concrete is poured in
once complete. A variation to this is CFA (Continuous Flight Augered) where the
piles are bored, Bentonite slurry is pumped in to stop the core collapsing and then
concrete (which is denser than Bentonite) is poured in. Bentonite is environmentally
harmful and is therefore not often used in the 21st century.
Pre-cast piles – pre-cast piles are brought to site and hammered into the ground. Not
often favoured due to the high noise levels associated with installation and the lack
of flexibility in terms of depth required.
Who is responsible for compliance with the Building Regulations?
The person physically carrying out the works (ie. builder)
What are the typical components of site investigations?
- Objective is to systematically collect and record data to help in design / construction
- Should include anything on adjacent sites that may impact and:
- Boundary hedges / fencing
- Existing trees
- Size, depth and location of services – gas, telephone, electricity, water, drains
- Existing buildings
- Ground water conditions
- Soil investigations – trial pits etc
What are continuous bored piles?
• Piles are drilled
• Reinforced and concrete poured close together to form a perimeter
wall before excavation.
• Not water tight so only used in dry conditions. Drained cavity
systems also required
What is double lap tiling?
Traditional method where a minimum of two layers of tile are
present in any one location
Each tile has nibs and nail holes to be affixed to roofing battens
Typically, tiles are only nailed (mechanically fixed) every 4th
course, depending on wind conditions
Used with a plastic underlay (sarking / roofing felt underlay). Creates a
barrier to snow, wind, driving rain etc. Barrier should be breathable to
allow moisture / water vapour to escape.
What is Rainscreen cladding?
Rainscreens are not curtain walls as such, as they provide a screening
function rather than an enclosure in its own right. A rainscreen is used to
shield a wall, whether this be of masonry, metal studwork or in some cases
glass. Usually a rainscreen is designed to permit some controlled leakage
with the main functions of resistance to air and water being provided by
the shielded wall behind
The basement construction for your project is in between two
adjoining properties, were there any Party Walls issues? What is a
Party Wall award?
A Party Wall Award - an agreement to carry out works where there is a party wall
issue. Will involve a record of the current state of the wall, methods for carrying out
the works, hours of working, access, protection required. Provisions for inspection &
making good damage. Legally binding document.
What are the different types of Concrete finishes?
Top Surfaces:-
Tamp - basic - not measurable - makes top surface flat
Wood Float - provides smoother surface - works aggregate
Steel trowel - better quality finish.
Power Float - good quality finish for placing of vinyl/carpet.
Formed Surfaces:- Aggregate Exposure, Bush Hammering.”
What is a foundation?
Function is to safely sustain and transmit to the ground on which it rests the
combined dead, imposed and wind loads of the structure
What is superstructure?
All internal and external structure above the substructure
Made up of primary (ext walls, stairs, roof, structural walls) and secondary
(suspended ceilings / raised floors, balustrades, doors) elements and finishes (tiles,
paint, stair nosings)
What other elements will be affected by the type of cladding systems
used?
Frame
Roof
M&E.
What are the technical disadvantages of steel frames?
Needs fire protection
Parts may need replacing
Price of steel is variable
Need experienced builders – additional cost
Even though steel components will not burn they will actually fail (collapse) before a
wood component in a fire.
What is contaminated land?
◼ Land may be contaminated with asbestos, oil, diesel, radon, etc.
◼ Affects land value and rental income
◼ Can be hazardous / damaging to people and buildings
◼ Covered by the Environmental Protection Act 1990
- Phase 1: Audit (desktop study)
- Phase 2: Survey (soil samples)
How is composite metal cladding fixed to a steel frame?
Bolted
Riveted
Welded.
What is an air brick?
A perforated brick to allow for ventilation into a room or an underfloor space. NOT a
weep hole.
What is the purpose of a threshold strip?
A lightly rounded metal strip over the joint between the floor finishes or coverings that
meet under the door leaf.
Prevents fraying, looks better and interrupts combustible flooring under fire doors
Where could you go to get Building Control approval on a project?
Your local authority building control services OR approved inspectors
Approved Inspectors are companies or individuals authorised under the Building Act
1984 to carry out building control work in England and Wales.
What happens if the building regulations are contravened?
Magistrates Court - Fine of up to £5k + £50 for each day it continues & must invoke
procedures within 6 months. Local Authority - May issue enforcement notice
requiring compliance or undertake works & recover costs
What is compartmentation?
− Prevent spread of fire
− Provides safe means of escape
− Structural elements should be protected to prevent collapse
− Approved Document B stipulates minimum requirements (30 or 60
mins) based on risk, use and location
What is a borehole?
A borehole can be used for soil investigation or for geothermal heating solutions.
Boreholes are the most suitable method of soil investigation when foundations are
over 3m deep
Geothermal boreholes are permanent boreholes that use the Earth’s natural heat to
raise the temperature of circulated water. This is a closed system and can be used to
heat the building above. It’s seen as a sustainable technology.
What is ‘sick building syndrome’?
Contribution of factors within a building which may cause people to feel dizzy,
sick, flu, stress, dry eyes etc. including;
− Bacteria in air conditioning / ventilation
− Artificial lighting
− Heating provisions / humidity
− Noise levels
• To minimise the potential of ‘sick building syndrome’ use natural ventilation,
correct lighting levels and place plant / machinery such as photocopiers in
separate rooms
What is stick system cladding?
• In the stick system, the curtain wall frame (mullions) and glass or opaque
panels are installed and connected together piece by piece.
• Stick curtain walling systems are versatile and allow for the integration of
other systems, such as sliding doors and windows. They tend to be less
specialised and can be built by all types of fabricators as they are not
dependent on having a large factory.
• However, stick systems do require multiple steps to erect and seal the wall,
which means more time is spent on site – an approximate rule of thumb
would be that 70% of the work is carried out on site, with 30% in the
factory. This incurs further costs, such as labourers’ time.
What are the elements of a flat roof?
Joists – fixed to wall plates to act as main support
Furrings – fixed to the top of joists to give required incline
Particle board – fixed to top of furrings to give flat surface
Felt – 3 layers bonded with bitumen to give waterproof covering
Stone chipping – To give protection to felt and to reflect sunlight
How is a foundation type determined?
The type of foundation is determined by;
Ground conditions and load bearing strata
Depths
Composition (stone, rock, sand, clay, peat)
Water table
Loads to be imposed (point loads, uniform loads, etc.)
What is the aim of the Landfill Tax?
To reduce waste & encourage recycling & waste management
Advantages and disadvantages of timber frame?
• Advantages: - Sustainable - Cheap and Quick • Disadvantages: Excess moisture / damp can lead to structural degradation Risk of insect or fungal attack Risk of fire spread —Special fire codes Differential movement between brick skin and timber frame
• Most common in residential construction
• Less weight than traditional masonry methods
• Alternative to traditional standard loadbearing masonry due to speed of construction
• Lighter construction means smaller foundations
• BRE recommends a maximum of 6 storeys for timber frame
• 2 Types:
Balloon Frames
+ Walls constructed as complete entities (all stores on 1 panel)
+ Floors are suspended from panels.
+ Restricts number of storeys.
Platform Lift
+ Walls constructed as a storey height element
+ Prevalent in the UK
+ Better suited for pre-fabrications
What are the different ways that the piles transfer their load to the
surrounding ground?
End bearing piles
Friction piles
Settlement reducing piles
Tension piles - tall chimneys, transmission towers and jetties
Laterally loaded piles - bridge piers, trestles to overhead cranes, tall chimneys and
retaining walls
Detail a Warm Roof?
• Insulation placed on top of the roof deck but beneath the waterproof
membrane.
• Vapour control usually placed under the insulation.
• Reduced risk of condensation as the ceiling or roof void is at a similar temperature
to the roof.
What types of fire detection are there?
− Manual (break glass call point)
− Automatic (heat / smoke detectors)
What is substructure?
All structure below the superstructure i.e. all structure below ground level including
the ground floor bed
