14 - Construction Technology and Environmental Services Flashcards
Construction Technology and Environmental Services - Extract from Candidate Guide - Aug 2018 (updated Feb 2022)
What are the main types of curtain walling ?
spandrel panel
shopfront window
rain screen cladding
Cladding = Cladding is the application of one material over another to provide a skin or layer. In construction, cladding is used to provide a degree of thermal insulation and weather resistance, and to improve the appearance of buildings
What is the RIBA plan of works ? and what are the stages ?
The RIBA Plan of Work organises the process of briefing, designing, constructing and operating building projects into eight stages and explains the stage outcomes, core tasks and information exchanges required at each stage.
0 - Strategic Definition 1 - Preparation and briefing 2 - Concept design 3 - Spatial Coordination - PA 4 - Technical Design - BC & T 5 - Manufacturing and Construction 6 - Handover 7 - In Use
How does the RIBA plan of Works 2020 differ from 2013?
More sustainable feature, sustainability, title of some of the riba stages, spatial coordination
Can you name some brick bonds ?
What bond is your case study ?
Stretcher
Header
English
Flemish
What are some building ages/eras ?
Georgian - 1714 - 1830 Victorian - 1837 - 1901 Edwardian -1901 - 1920 Post war etc
How would you identify Japanese knotweed ?
RICS have an information paper
- Red or green/purple tinge
- Bamboo like appearance
- Zig zag stem
- Cream flowers
- Shovel shaped green leaves
What are the types of mortar used ?
Type O
• Weak strength 350 PSI
• Used for repointing or some stone work
Type N
• Strength 750
• Common type with slow curing and good workability
Type S
• Strong 1800 PSI
• Used in exterior walls and foundations
Type M
• Strongest 2500 PSI
• Used in exterior walls, foundation and high load bearing walls
What is a green roof ?
A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems.
What is the built up of a warm roof ?
- Roof covering
- Insulation
- Vapor barrier
- Roof deck
- Joists
- Plaster board and plaster
What are the benefits of a single ply membrane ?
Benefits include : • Easy to install so in turn cheaper installation costs • Resistant to UV damage • Durable • Cheap to repair • Hardwearing • Various colour choices • Low maintenance • Recyclable • Longer lifespan
What is the use or need for a vapour barrier in warm roof construction?
To stop the internal moist air moving into the insulation and roof covering section. (interstitial condensation)
How would you know if the proposed ventilation was suitable in terms of the requirements from approved documents?
I would references the required output in relation to the proposed ventilation looking at both approved document F - Ventilation and approved Doc C - Site preparation and resistance to contaminates and moisture.
What are some additional considerations in relation for a cold roof ?
- Floor to ceiling heights
- External roof heights
- Existing roof covering
- Ceiling joists location
- Cross ventilated cavity (to avoid interstitial condensation)
What potential material could you use for flashing’s ?
- Galvanized steel, which is inexpensive but lacks the durability of other metals.
- Lead-coated copper.
- Anodized aluminium.
- Terne-coated copper.
- Galvalume (aluminium-zinc alloy coated sheet steel).
- Polyvinylidene fluoride.
What is a flashing ?
Flashing is a sheet of thin, impervious material used to prevent water penetration or seepage into a building and to direct the flow of moisture in walls. Flashing is particularly important at junctions such as roof hips and valleys, joints between roofs and vertical walls, roof intersections or projections such as chimneys, dormers, vent pipes, window openings, and so on.
There are two categories of flashing, exposed and embedded. Exposed flashings are partially exposed to the outside and usually made of a sheet metal, while embedded (or concealed) flashing can be metal or non-metal and are typically used at the base of cavity walls, above openings, at sills and shelf angles (a structural steel member that supports and transfers the brick’s dead load back to the building frame), and under copings.
Can you name some items of the roof structure ?
Deck, VCL, insulation, coverings, fixings
Can you some parts of a typical residential dwelling (the construction) ?
What building regulation did you considering in your case study project ?
Candidate specific
Sketch a warm roof
Sketch a cold roof.
What options are available for houses that cannot be connected to the main drains/sewers?
- Septic tanks
- Rain water harvesting
- Grey water irrigation
What is the first fix stage in construction?
First fix (sometimes described as shell and first fix ) is a short-hand term used to describe the processes that are undertaken during construction works up to the point of applying internal surfaces – typically plaster. It is normally used in relation to the work of specific trades such as carpenters, plumbers and electricians.
Generally first fix will include constructing the structure, cladding, flooring, doorframes, stairs and so on and installing cables for electrical and ICT distribution, pipework for water and gas distribution and heating ventilating and air-conditioning (HVAC) distribution. First fix is not normally visible when looking at the finished building. Where possible first fix should be tested before second fix (for example, plumbing riser stacks).
- Electrically – Installation of conduits and back boxes and pulling through cables ready for final connection.
- Mechanical – pipe and duct work put down or run accordingly ready to be boxed in
What is the second fix stage in construction?
Second fix takes place after the internal surfaces have been applied. It comprises those items that are visible in a finished area and are held back to avoid damage, or sadly sometimes theft. This may include fitting internal doors, skirting, architraves, handrails, fixtures and fittings, including connection of appliances (such as electrical equipment, sanitaryware, radiators, and so on) testing and commissioning.
Typically there will be a change of trades operating on the site, and a break in activity for some trades between first and second fix.
- Electrically – Cable connections and closing of plugs and switches, installation of lights and sensors.
- Mechanical – Mounting radiators, extending pipework to fixtures and fittings. Installation of ventilation.
What are the elements of a domestic heating and hot water system?
- Cold water storage
- Expansion tank
- Boiler
- Hot water cylinder
- Radiators
What are the elements of a domestic electric system?
- DB Board
- Consumer unit
- RCD - Residual-current device
- MCB – Minatare circuit breaker
What are the typical distances between ceiling joists in a rafter and purlin roof?
400-450mm centres
What is the difference between a gable, hipped and mansard roof?
- Gable – Triangular end supporting the two slopes.
- Hipped – all roof pitches meet at multiple or single ridge and slope down to all the walls.
- Mansard Roof – Steep front face pitch with a shallow pitch/flat roof on top. Usually have dormer windows projecting through.
What is the difference between a jack rafter and a common rafter?
- A common rafter is any rafter extending between the exterior wall and the ridge.
- A Jack rafter is a shorter secondary rafter used in the construction of a hipped roof
What is a flitch beam?
A timber beam sandwich. A steel plate is bolted between two timber beams to add strength. Lighter system to steel beam.
What considerations should you take when slating/tiling a roof?
Pitch of the roof. What the existing roof load was and if the existing timbers are strong enough.
What issues should be considered when replacing a flat roof?
- Age
- Extent of repairs required
- Access
- Costs
- Planning requirements
- Use of the room
- Insulation
What building regulation implications are there when carrying out roof refurbishments ?
Part L – Conservation of fuel and power - Comes into effect when 50% or more of the roof is being refurbished. The thermal efficiency also needs to be upgraded or meet current regulations as close as possible.
What are weep holes ?
Small openings in the outer wall of masonry construction and are found around openings aboveBrick and stone are porous materials and can absorb and store water. The inclusion of weep holes in masonry walls is intended to serve two purposes:
Drainage: They provide an opening that allows the drainage of any moisture that may reach the back of a wall, or the inside leaf of a wall (such as a cavity in cavity wall construction) from the outside through penetration, capillary action, condensation, leakage or flooding.
Ventilation: They allow ventilating air to the back of a wall to help prevent mildew, dry rot and damp which might otherwise reduce the life or performance of building materials such as cavity wall-ties, cavity insulation and so on.
What is the spacing between weep holes?
Generally 600mm centres bust 450mm is better practice
Where are they typically found (Weep Holes) ?
Where there are penetrations in a wall for openings with a cavity barrier. Where flat roofs meet the wall, door or window openings, where the slab meets the walls etc
What material are cavity wall ties made from ?
- Fishtail, wire butterfly, modern stainless steel
- Originally used to be galvanised steel. This used to corrode and crack the wall. Plastic was then introduced but this was not adequate so the use of stainless steel ties was introduced.
What is the typical width of a cavity?
- Traditional cavity would be 50mm
* Modern cavities are 100mm but can be greater for better thermal efficiency.
What is the spacing between wall ties?
- 450mm vertically
- 900mm horizontally
- 300mm vertically from the vertical edges of all openings, movement joints and roof verges
- 225mm horizontally from the vertical edges of all openings, movement joints and roof verges
- Ref Approved Doc A – Structure – 2C8
- BS EN 845-1
How would you identify cavity wall tie failure? Why does it occur and what are the remedies?
- Bowing walls
- Horizontal cracking every 4 or 5 courses
- Potential staining to the mortar
- Failed ties are due to corrosion
What is a movement joint and why are they used?
An expansion joint or movement joint is an assembly designed to safely absorb the heat induced expansion and contraction of construction materials. Allows some movement from settlement or differential settlement.
How critical is the type of mortar used on the construction of a building?
The type of mortar used is dependent on the type of wall and materials used. Older walls will typically use lime mortar to allow moisture to travel. This is often replaced with cement mortar which can effect the brickwork if moisture cannot escape.
What is the general principle for choosing a mortar type?
Mortar needs to be sacrificial. It needs to allow moisture to travel out of the wall which prevents damage to the masonry.
What are typical mortar mix ratios?
- Typical mix – 1:1:6 (cement, lime, sand)
- Lime – 1:3 (lime, sand)
- High compression – 3:1:1 (cement, lime sand)
What type of brick bonds are there and what can they show?
- Garden wall – two stretcher courses with a header course on top
- Flemish – stretcher course with a stretcher and header course on top
- English Bond – Alternating stretcher and header courses.
- Stretcher – alternating stretcher faces
- Stacker – stretcher face stacked directly above each other.
What is OSB? How is it different to plywood?
- Orientated Strand Board is formed by layering strands or flakes in specific directions and compressing the strands with resin.
- Plywood is laminated layers of wood.
- OSB is cheaper and can warp if exposed to moisture. Ply tends to hold nails better.
What is the difference between windows and glazed curtain walling?
- Curtain walling does not take any structural load but can withstand wind.
- Windows have a lintel detail above to ensure the structural integrity.
Describe two methods available to prevent penetration of water and moisture into basements ?
- Type A – Barrier Protection
- Type B – Structurally Integral Protection
- Type C – Drained Protection (Cavity Drain System)
- BS 8102:2009
What typical issues are faced with steel framed houses?
Structural metal frame and a roof truss constructed of tubular metal with a shallow pitched asbestos roof and profile metal sheets. Usually bricked or rendered at ground floor. Mortgage providers tend not to prefer them. The steel frame can corrode. The ground floor slabs can crack. Metal lathing corrodes. Asbestos roof starts to deteriorate. The only way to confirm if the structure is sound is by opening it up. They are generally less energy efficient that timber and brick.
What are the comparatives between steel and concrete framed construction?
- Programme – Steel is quicker to erect and the reduced time on site reduces overheads.
- Quality Control – Pre-fab of steel means better quality control to pouring concrete frames in situ. Offsite pre-fab increases the overall speed and improves safety.
- Design Flexibility – Both can create large open column free spaces. Concrete can form any shape whereas steel is limited to how you can shape it.
- Sustainability – steel is recyclable but concrete buildings are generally more energy efficient.
- Cost – Steel is more expensive but programme savings may make up for this.
What is glulam?
Structural timber constructed by laminating sections of wood. Prior to bonding, sections are placed together with the grain of each piece running parallel to the grain of the next piece.
What is an RSJ and how is this different to a UB?
- Rolled steel joist include tapered flanges which required tapered washers.
- Universal beams had parallel flanges and are easier to work with as the web has uniform thickness.
Outline the different types of foundations and when they would be used.
- Strip Foundation – shallow foundations for lightweight structures, typically houses.
- Raft Foundation – Used to spread the load from a structure over a large area. Normally the entire area of the structure.
- Pad Foundation – Used to support individual point loads for example, from columns in an industrial unit.
- Displacement Piled – Pile shaft is driven into the ground resulting in the soil being displaced. Pile transfers load down to sound ground conditions.
- Non Displacement Piled – Soil is removed and the hole is filled with concrete or a pre-cast concrete pile is dropped into the hole.
What is an underpinning sequence and why is it necessary ?
Underpinning requires removing the subsoil beneath the foundation and filling it with concrete. If it is done in one go over large spans, the structure will drop. Therefore, underpinning is carried out in sectional sequences so that the structure is still supported fully whilst the new concrete is poured and cures.
What are the different methods of construction between early 20th century house and modern house foundations, walls and roof.
- Foundations – 1900 house would have stepped brick. Modern house would have concrete strip.
- Walls – 1900 house would be solid brick or have an uninsulated cavity. Modern house will have a cavity with minimum 100mm insulation.
- Roof – 1900 house would have rafter and purlin roof or king/queen post with covering stone, slate or clay tiles. Modern house would probably have a trussed rafter pre-fab. Covered in a variety of materials depending on who owns the house.
Can you name some none traditional construction ?
- 13.1.1 Whimpey No Fines (1940’s – 1960’s)
- No-fines houses were built with a ten-inch (254mm) concrete shell cast in-situ
- The concrete for the entire outer structure was cast in one operation using reusable formwork.
- Ground floor was also concrete; the first floor was made with traditional timber joists and floorboards.
- Interior walls were a mixture of conventional brick and blockwork construction. To weatherproof the structure, the external facade was rendered.
What is a king post truss ?
A king post (or king-post or kingpost) is a central vertical post used in architectural or bridge designs, working in tension to support a beam below from a truss apex above (whereas a crown post, though visually similar, supports items above from the beam below).
In aircraft design a strut called a king post acts in compression, similarly to an architectural crown post.
What is a queen post truss ?
A timber roof truss is a structural framework of timbers designed to bridge the space above a room and to provide support for a roof. Trusses usually occur at regular intervals, linked by longitudinal timbers such as purlins. The space between each truss is known as a bay.
Rafters have a tendency to flatten under gravity, thrusting outwards on the walls. For larger spans and thinner walls, this can topple the walls. Pairs of opposing rafters were thus initially tied together by a horizontal tie beam, to form coupled rafters. But such roofs were structurally weak, and lacking any longitudinal support, they were prone to racking, a collapse resulting from horizontal movement. Timber roof trusses were a later, medieval development. A roof truss is cross-braced into a stable, rigid unit. Ideally, it balances all of the lateral forces against one another, and thrusts only directly downwards on the supporting walls. In practice, lateral forces may develop; for instance, due to wind, excessive flexibility of the truss, or constructions that do not accommodate small lateral movements of the ends of the truss.
What are strip foundations ?
A continuous strip of concrete supporting load-bearing walls. For a single storey building strip foundations will typically be 450mm wide and at least 200mm deep, and for two storey building 600mm wide and 200mm deep. Strip foundations are used to support a line of loads, either due to a load-bearing wall, or if a line of columns need supporting where column positions are so close that individual pad foundations would be inappropriate.
What is a raft foundation ?
A reinforced concrete raft or mat is used on very weak or expansive soils such as clays or peat. They allow the building to ‘float’ on or in the soil. A raft is used where the soil requires such a large bearing area that wide strip foundations are spread too far, making it more economical to pour one large reinforced concrete slab. A raft is an alternative to piles as it can be less expensive.
Raft foundations are used to spread the load from a structure over a large area, normally the entire area of the structure. They are used when column loads, or other structural loads are close together and individual pad foundations would interact.
What is a pad foundation ?
Used when isolated loads need to be supported, for instance to support the columns of a steel or post and beam frame house. The load is concentrated on a small area.
Pad foundations are used to support an individual point load such as that due to a structural column. They may be circular, square or rectangular. They usually consist of a block or slab of uniform thickness, but they may be stepped or hunched if they are required to spread the load from a heavy column. Pad foundations are usually shallow, but deep pad foundations can also be used.
What is a piled foundation ?
Pile foundations are deep foundations. They are formed by long, slender, columnar elements typically made from steel or reinforced concrete, or sometimes timber. A foundation is described as ‘piled’ when its depth is more than three times its breadth (ref. Atkinson, 2007).
Pile foundations are principally used to transfer the loads from superstructures, through weak, compressible strata or water onto stronger, more compact, less compressible and stiffer soil or rock at depth, increasing the effective size of a foundation and resisting horizontal loads. They are typically used for large structures, and in situations where soil is not suitable to prevent excessive settlement.
What are the types of piled foundations ?
- Bored Piling.
- Driven Piling.
- Screw Piling.
- Mini Piling.
- Sheet Piling.
What are the options for basement waterproofing?
- Type A System: Barrier Protection
- Type B System: Structural Integral Protection
- Type C System: Cavity Drainage System
What is a Type A System?
A Type A system uses a barrier protection geo-synthetic method typically applied during construction. E.g Bonded sheet membrane, liquid applied system, cementitious systems and crystallization powders and slurries.
Three methods of application: External Applied, Sandwiched or Internal Applied.
What is a Type B System?
Type B systems rely on the structural integrity of the construction materials typically watertight concrete with a free water content at 0.45 or below.
Low permeability concrete with good joint detailing.
What is a Type C System?
A type C system is known as a cavity drainage protection. Type C doesn’t resist hydrostatic pressure like a type A & B but provides protection via water management using drainage channels and pumps.
What is substructure?
All structure below the superstructure i.e. all structure below the ground including the ground floor bed.
Sketch the internal wall insulation.
72.5MM = 0.26 U VALUE
Can you talk me through some of the inclusions from Approved Document K regarding stairs ?
