Construction Technology Flashcards
1
Q
How much does it cost to excavate 1m3 of soil?
A
Excavate - 10/m3 (tender returns £6- £28)
Disposal - £45/m3
EO contaminated non-haz - £25
EO contaminated haz - £80
Landfill tax - £175
2
Q
What is an ASHP and how does it work?
A
Air Source Heat Pump
Air is taken from outside, air boils refrigerent into a gas, gas goes through a compressor to get extra hot, transfers heat to water through plate heat exchanger to warm water to showers/baths/radiators.
3
Q
What are the different types of asbestos?
A
Chrysotile (white asbestos)
Amosite (brown asbestos)
Crocidolite (blue asbestos)
4
Q
Why was asbestos used?
A
Strong, incombustible, heat-resistant and sound-absorbent,
5
Q
How can we protect ourselves from asbestos?
A
- Asbestos survey to identify and manage ACM, or to remove prior to demolition
- Asbestos awareness training, so people don’t disturb it
- Must be within management plan
6
Q
What information would you expect from the design team at RIBA Stage 4?
A
Technical design.
- Fully coordinated services, structure & architecture
- Fully detailed
- Specialist subcontractor design & spec
7
Q
What’s the difference between RIBA PoW 2013 and 2020?
A
Developed design is now spacial coordination
Construction is now Manufacturing and Construction
8
Q
What Stages are “project” stages according to RIBA PoW 2020?
A
Stages 1 to 6
9
Q
What level of information would you expect at Stage 2?
A
- Concept design
- Outline proposals for structural design, building services systems, outline
specifications - Final project brief issued
10
Q
What level of information would you expect at Stage 3?
A
- Coordinated and updated proposals for
structural design, building services systems, outline specifications
11
Q
What would you do if the level of information provided was not adequate?
A
- Important to ensure you communicate what you expect for each stage so this doesn’t happen
- Inform design team/PM/client of requirements
- If programme extended + design progressed, great
- If not, ensure in clarifications to state level of design information + ensure client knows
- Update risk contingencies accordingly
12
Q
What would be included in the build up for piles?
A
Piling mat - m2
Piling plant - item
Moving piling rig into position - nr
Piles - unspecified
EO for piling casing - unspecified
Disposal for excavated arisings - m3
EO for breaking through obstructions - nr/m3
Cutting off piling tops - nr
Pile tests - item
Pile caps, ground beams also required
13
Q
How would you dispose of soil?
A
Contaminated vs non-contaminated
Of the contaminated, split between hazardous & non-hazardous
14
Q
Different types of pile foundations?
A
- Bored/replacement
- Driven/displacement
- Secant pile walls
- Contiguous pile walls
15
Q
What type of foundation would you use in a city centre with low bearing capacity soil?
A
Bored piles because:
- Require deep penetration to get to soil w/ adequate bearing capacity
- Bored gives less vibration/noise, so won’t disturb neighbouring structures or tenants (likely in city centre)
16
Q
When would you use strip foundations?
A
- Often for masonry facades where strip will follow the line of the structural brick wall
- Good soil in terms of bearing capacity
- Light load
17
Q
What would be included in the build-up to a strip foundation?
A
- Concrete
- Reinforcement
- Formwork
18
Q
What would be included in the build-up to a pad foundation?
A
- Concrete
- Reinforcement, though not required. Reinforcement allows for shallower pads.
- Formwork
19
Q
Why would you use pad foundations?
A
To spread the load of a column over a wide surface area.
Possible if the load isn’t huge and/or the soil bearing capacity is good
20
Q
What is tensile strength?
A
The strength of a material under tension, e.g. longitudinal stress, being pulled apart
21
Q
What is compressive strength?
A
When a squeezing force is applied on the object
22
Q
What forces act on a beam?
A
Tension on the bottom, compressive on the top
23
Q
What is shear force?
A
Force applied perpendicular to a surface, in opposition to an offset force acting in the opposite direction
24
Q
What is the price of steel?
A
Market fluctuates
Steel beams/columns, £2500/t
Massive steel structures, £4000+/t
Rebar/reinforcement, £1300/t
All incl subcontractor prelims
25
What are different concrete grades?
Compressive strength of the concrete after 28 days
For instance, C10 has the strength of 10 newtons, C15 has the strength of 15 newtons, C20 has 20 newtons strength and so on
26
Cost of concrete C32/40?
£195/m3
27
When would you use steel for frame construction?
- Where large open spans are required such as cinemas, offices
- Tall buildings as it has better strength to weight ratio
- Where flexibility is important
28
When would you use concrete for frame construction?
- Where large open spans are not required e.g. residential
| - Flexibility is less important
29
Pros/cons of concrete?
Pros
- Good thermal insulator
- Good acoustic insulator
- Doesn't require additional fire protection
- Can be cheaper than steel
- In situ good for cashflow as it's slow
- Cladding easily connected
- Insuti means late changes possible
- Can deal with complex geometry better than steelwork
Cons
- Good concrete subcontractor important
- Bad for embodied carbon
- Heavy
30
Pros/cons of steel?
Pros
- Good strength to weight, lighter than concrete
- Tension strength means good for long spans
- Quality assurance, prefabricated
- Quick to assemble
- Recyclable
- Not combustible
Cons
- Bad for embodied carbon
- Requires fire protection, will fail under fire otherwise
- Can corrode
- Requires experienced builders
- May need parts replacing
- Price fluctuates
31
How would you fix curtain walling to a facade?
- Bolted (useful when may require being undone & cheaper than welding)
- Riveted (fastest, like a nail)
- Welded (melted together, maximum strength)
32
What's the difference between glulam and CLT?
Glulam - layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives. LENGTHS OF TIMBER, GOOD FOR BEAMS/COLUMNS.
Cross-laminated timber (CLT) is layers of timber (lamellas) bonded perpendicularly to one another, resulting in structural strength across two dimensions. PANELS/SLABS
33
What are the pros/cons of timber-framed buildings?
Pros
- Sustainable (FSC)
- Low embodied carbon
- Good for carbon sequestering
Cons
- Can't do high buildings, column requirements become too big
- Requires acoustic and fire protection
- Expensive
34
What prefab experience do you have?
- Early cost planning bathroom pods
| - Early cost planning for a modular building for a university space
35
What was included in a cost estimate for the modular building?
- Site prep
- Strip foundations
- Pod costs (market tested)
- Prefab stairs (market tested)
- Delivery and installation costs (market tested)
- Allowances for external windows & doors
- Services
- Fit Out
36
Why would you use pre-fab?
- Economies of scale; could be cheaper
- Sustainable credentials; less waste in off-site manufacturing
- Sustainable credentials; factory construction can allow for better product w/ better insulating properties, precision engineering..
- Consistent quality
- Safety, less risk constructing in factory controlled environment
- Fast installation time
37
Why would you not use prefab?
- May not always be cheaper
| - Finished product sometimes less desirable in the market; stigma attached to them
38
When comparing steel and concrete, which was more economical?
Office - RC concrete option was more economical, however client went for timber/steel due sustainable credentials
School - Steel required because of auditorium spans.
39
What's a grade 1 vs grade 2 listed building?
Grade I: buildings of exceptional interest. Buckingham Palace
Grade II*: particularly important buildings of more than special interest, Battersea Power Station
Grade II: particularly important buildings of special interest, BT tower
40
What's a stick system?
Curtain wall installation technique
Secondary steel frame attached to structure, curtain wall fixed to this.
Cheaper, slower
41
What's a unitised system?
Curtain wall installation technique
Pre-fabricated in modules off-site and delivered in panels
Benefits of prefab factory conditions, fast install but longer lead time
42
What is a rain screen cladding system?
- Non-structural external surface
- Protects everything inside from external weather
- Formed of outer protective skin (metal, timber, glass, composite panels), supporting frame, a cavity and water-resistant internal materials which includes a layer of insulation
- Three basic types are drained and ventilated, vented, and pressure equalised rainscreen systems
43
What is the size of a brick?
Standard size - 215mm x 102.5mm x 65mm
44
How many bricks are in a m2?
60 approx.
45
What are the different types of brick bond?
Flemish bond - The bond has one stretcher between headers, with headers centred over the stretchers below
Stretcher bond - most common, walls just half a brick wide. Stretcher face side showing.
46
What is a steel table?
Table that provides standard information on steel sections.
Different table for different beams/columns, e.g. UB and UC.
47
What are retaining walls?
They act as an earth retaining structure for the whole or part of their height
48
What considerations should a Contractor make when building a retaining wall?
Pressure of water/earth acting on wall
49
What are the main types of excavation?
- Open
- Perimeter Trench Excavation
- Complete excavation
50
What is open excavation?
- Use battered excavation technique which is excavating the soil with the sides left at a safe angle so as to not collapse
- Save money on temporary support work
- Extra excavation costs due to extra soil being removed to ensure sides are at a safe angle
- Requires free space on site for angled sides. Wouldn't work on site boundary.
51
What is perimeter trench excavation?
Trenches are dug with required support around basement perimeter. Basement walls are formed, then inside of basement is excavated.
52
What is complete excavation?
- Centre of basement is excavated
- Basement slab is cased while sides of excavation are supported by struts
- Basement walls formed
- USED WHEN SUBSOILS ARE FIRM
53
What are the 3 main types of basement construction?
a) Retaining wall and raft (monolithic) - slab raft foundation distributes building load. Basement walls are retaining.
b) Box and Cellular - similar to above but internal structural walls transfer and spread loads over raft, dividing basement into cells
c) Piled - superstructure load carried to basement floor by columns and treasferred into ground via pile caps & piles
54
What are connections (steel) and what percentage would you expect them to be?
- Plates, bolts or welding
| - 5%-15% by weight
55
Cost/sqft for RC concrete frame?
£36/sqft on a recent project excl on costs, but varies project - project
56
Why were piles more economical than pad foundations in your example?
Because the soil capacity was so poor, the size of the pad was huge. Cheaper to have much smaller diameter pile but go deeper, end bearing pile.
57
Why would you retain a facade?
- Listed
| - Aesthetics
58
How would you retain a facade?
Not something I have ever had to do but you'd have to install temporary works, propping.
Knock rest of building down, then install permanent support to new structure.
Finally, remove propping.
59
List features on an old facade
- Quoin
- Ornamental bands
- Gargoyles, pots
- Chimneys
- Portland stone
- Terracotta
60
What are the building regulations?
Statutory instruments that set out the minimum performance standards for the design and construction of buildings.
Supported by approved documents A - R & regulation 7.
61
Name the approved documents.
A - Structure
B - Fire safety
C - Site preparation and resistance to contaminants and moisture
D - Toxic substances
E - Resistance to the passage of sound
F - Ventilation
G - Sanitation, hot water safety and water efficiency
H - Drainage and waste disposal
J - Combustion applications and fuel storage systems
K - Protection from falling, collision and impact
L - Conservation of fuel and power
M - Access to and use of building
N - Glazing safety (withdrawn, ss by park K)
P - Electrical safety
Q - Security
R - Physical infrastructure for high speed electronic communication networks
Regulation 7 - Materials and workmanship
62
What is substructure?
All structure below the superstructure i.e. all structure below the ground including the ground floor bed.
63
What is superstructure?
All internal and external structure above the substructure.
64
What is landfill tax?
- Brought in by govt. in 1996
- To reduce landfill waste and promote recycling/reuse, & promote research into waste practices
- Applies to all waste disposed of at licenced landfill sites unless specifically exempt
- Administered by hm customs and excise
65
What are the landfill tax rates?
£94.15/ tonne for active waste
£3.00/tonne for inactive (inert) waste
(Rates from April 2020 - 2021)
66
What is active waste?
- Substances that either decay or contaminate land - which includes household waste.
- Expensive to dispose of.
67
What is inactive waste?
- Biologically or chemically inactive. Don't give out harmful residue.
- Do cause problems with filling up areas.
- Cheap to dispose of.
68
What are foundations?
Foundations provide support for structures, transferring their load to layers of rock and soil that have sufficient bearing capacity
69
What are the main components of concrete?
Water, aggregate (rocks, sand etc), cement
70
What is curtain walling?
- Glazed or opaque infill panels fixed to a lightweight frame
- Vision panels, spandrel panels, aluminium panels, louvres/vents.
- Fixed using stick or unitised system
- Lightweight, maximise daylight, can provide good thermal performance (opaque panels)
- Installation costs/maintenance costs can be high
71
What is pre-cast concrete cladding?
Concrete panels are formed off-site
- Off-site manufacturing means it can be moulded into different shapes, colours, in controlled conditions so less wastage
- Transported to site, tower/mobile cranes lift them to position
- Panels can be fixed to frame or can be supporting itself
72
What is a vented rainscreen cladding system?
- Cavity open at bottom
- Provides drainage but no ventilation
- Warm cavity, no ventilation (should be called drained really)
- Warm cavity provides dew point close to outside
- Shouldn't be used above 4 storeys due to higher wind load + greater risk of water penetration
73
What is a drained and vented rainscreen cladding system?
Not watertight
- Cavity must be open at top and bottom
- Cavity must provide drainage and promote ventilation
- Protect cavity with overhang
- Protect backing structure with moisture barrier (VCL)
- Non-hygroscopic or closed cell insulation (PIR or Rockwool)
- Excessively high D+V systems should be avoided (12m or less)
74
What is a Pressure Equalised rainscreen system?
Cavities are compartmentalised
- Openings calculated to allow rapid ingress and egress of air resulting in very low wind load on panel themselves
- Water ingress reduced by "equalisation" of internal and external pressures
- Drained above compartment levelsS
- Suited to tall areas of rainscreen, typically used over 4 storeys
- Design intensive
- Compartmentalisation stops spread of fire
75
How are bored piles installed?
Continuous FLight Auger for bored piles
Drills hole into ground, pulling up earth as concrete is poured down at the same time through hollow centre of auger.
Steel then forced into wet concrete
76
Why did the pad foundations increase in depth?
Soil investigations returned informing structural engineer.
Developed design also meant more calculations had gone into this stage.
77
Are pile foundations always more economical than pad foundations?
No, if soil integrity was good I imagine that a shallow pile would be more economical than a deep-reaching pile
78
What did you include for cost advice to the client for the costs of the basement on your south London project?
- Cost of excavation
- Cost for breaking out existing dock walls
- Cost for secant piled wall
- Cost for waterproofing (waterproof concrete + membrane, Type 1)
- Cost for slab
- Cost for stairs & ramps
- Cost for columns, walls
- Cost for fit-out finishes
- Services
79
Do female piles require reinforcement/?
Different scenarios will have different requirements, project I worked on female was reinforced
80
What are the different types of soil you would excavate?
- Inert
- Contaminated haz (active)
- Contaminated non-haz (inactive)
81
What's the difference between fixtures, fittings and joinery?
Joinery = woodwork such as doors, frames, stairs
Fixtures = any furniture that is FIXED to a building such as in-built cupboards
Fixings = easily removed, perhaps only held in by a nail, such as a picture or hung mirror
