Document Questions Flashcards
Can you tell me how you’ve advised a client on the foundation selection?
Soil type
Cost/Time
Type of structure
Buildaibility (access, proximity, site conditions)
What is piling?
Where RC concrete is in the ground to take the load of the structure
Typically reinforced
Used on large buildings with heavy load and subsoil is not able to take the load
What are the advantages of CFA piling?
Low levels of noise and vibration
High load bearing
Suitable for a wide range of ground conditions
What is the difference between displacement and replacement piling?
Displacement driven into the ground without excavation
Replacement is CFA piling
What is a typical ground floor slab build up?
Finish
Screed
DPM
Insulation
Slab
Sand/Blinding
DPM below slab`
What is included within one of your projects substructure?
On Tolworth Phase 1 we had a piled substructure which included:
- 600 dia piles
- Pile Caps
- 300mm RC ground bearing slab
When would you advise to use a piled foundation?
High rise building
High load bearing
Subsoil cannot hold weight of structure
Explain activities involved when piling?
Measure in line with Section 1 of NRM1
Forming pile mat Mobilisation/moving of pile rig Pouring insitu RC piles Cutting top of piles Pile Caps Pile testing Pile casings if applicable
Why would you use rotary bored piles instead of CFA?
Rotary bored piles Larger diameter than CFA Support greater loads Penetrate ground too hard to CFA Pile can be reinforced entire length because the rotary bored technique enables the entire cage to be added as it can be dropped prior to concrete pour
What was the cost difference per pile for RTB and CFA?
Dependant on dimensions and rebar density
RTB £25k/pile (>900 dia, 60m deep) CFA £4k/pile (700 dia, 30m deep), CFA £2.5k/pile (600mm dia, upto 26m long)
How do piles work in regards to transferring loads?
End bearing will transfer load to strata
Friction will rely on the strength of the soil to be able to create friction between piles to prevent movement and transfer load
Why would you use CFA piles instead of Bored?
Better soil conditions
Cost
Quicker than Bored (concrete done as excavating)
How would you measure a Steel Frame?
Measure steel in tonnage
Intumisant paint
Accessories and fixings could be included
Plates and holding down bolts cast into foundation
Each steel member measured in tonnage
What are the main forms of legislation in the industry?
Construction Act (HGCRA1998) Local Economic and Democracy Act HASAWA CDM Regulations Building Regulations Fire Regulations Party Wall Act Proceeds of Crime Act Anti Bribery Act
What are the CDM Regulations?
The Construction (Design & Management) Regulations (CDM 2015) are the main set of regulations for managing the health, safety and welfare of construction projects.
Pre-construction activities to ensure works are being carried out safely
What are the Building Regulations?
List of approved documents ( A - R) which building work must be complied to :
Part A- Structure
Part B- Fire
Part Q- Security of Dwellings
What are the Fire Regulations?
Regulations that specify to legislation and laws relating to fire as set out in Part B of the Building Regs
What is your role in relation to the CDM Regs?
Due to my input in reviewing drawings and having an influence on design I am aware that I am seen as to having a role as a designer in relation to CDM Regs.
Name different types of planning consent types
Outline
Full
Non material amendments
What do the GLA state regarding units per core?
GLA this should not exceed 8 residential units per core.
How would you build a rate for a frame?
C40/50/60 concrete to: - Ground Bearing Slab - Suspended Slabs - Columns - Beams - Transfer beams/slabs - Beams - Walls Reinforcement (to S.E recommendation)Formwork to soffits Formwork to edges
What is a cold roof and its + & -
Waterproof layer
RC
Void for ventilation
Insulation
Better for heavy plant on roof
Requires void to avoid damp / condensation
Difficult to construct
What is a warm roof and its + & -
Waterproof layer
Insulation
Vapour Control
RC
Typically better for warmth and waterproofing
Not great for greater loads on roof
Why are transfer slabs required?
To help with load bearing- for example on my project there were columns on the GF that were required to be moved and the load from above had to be transferred via a transfer slab into the columns
What are the advantages of using precast concrete frame?
Produced in factory-controlled conditions
Eliminates curing times and formwork
Can be assembled in cold weather and generally by semi-skilled labour
What are the disadvantages of using precast concrete frame?
Less flexible in design terms
Longer lead times
What factors should be considered when choosing between a frame type?
Fire proofing requirements
Acoustic requirements
Time
Site logistics (e.g. delivery of materials to site, on/off site storage, plant restrictions)
Cost
Requirements for thermal mass for a low energy design solution
Repetitiveness
In your documents you have highlighted the advantages/ disadvantages of Steel v Concrete. Could you talk me through some of these?
Steel
Advantages:- Quicker to construct- Recyclable- Strong tensile strength Lighter than concrete
Disadvantages- More volatile pricing - Low compression strength - Low sound/fire resistance - Requires soundproofing
Concrete
Advantages
- High compression strength
- Good noise resistance
- Good fire protection
- Low maitenance
Disadvantages
- Slower to construct
- Need for reinforcement
- High embodied carbon-
- Not as square and flat as steel
Are you aware of any renewable technology techniques?
London 0% Carbon Local labour Photo voltaic panels Blue / Green Roof Presence detectors ASHP GSHP
Difference between steel / concrete with regard to life cycle costing?
Concrete
Cheaper / Easier to repair
More flexible
Steel
Difficult to repair as done in large spans
Expensive
What is a movement / expansion joint?
A movement joint, is a dynamic component that is designed to relieve or absorb movement between structural elements and help prevent cracking.
What did you measure in your transfer slab?
Insitu concrete @ £150/m3
Reinforcement @ £1,200/t
Formwork @ £60/m2
Expansion Joint
Was the internal wall construction a SBD requirement?
The Architect confirmed that SBD was achieved using the typical wall build using drylining but this was a client preference to increase the security of the walls
What would you expect to change if a building was taken from 10 - 30 storeys?
Wet Risers Brick slip system FF Lifts Sprinklers over 11m
What is the build up of the mansard roof?
Standing seam roof (zinc) Blockwork Insulation Blockwork Plaster Finish
What are the types of facade relevant to your experience?
Traditional masonry wall
SFS system with handlaid brick
Curtain Walling
What is the typical build up on a masonry external wall?
Brick, cavity, insulation, block, wall ties, masonry supports
275mm thick
What is the typical build up on an SFS system?
Brick Cavity Rockwool insulation Tyvek Breather membrane Silicate board Masonry supports SFS
How would you support brickwork on the superstructure of your project?
Proprietary masonry support
Brackets Shelf Angles
Alternative scaffold systems?
Scafford
Mast Climber
Abseiling
Crane
How are facades fire proofed?
Cavity Trays
Rockwool Insulation
Tyvec (fire barrier)
What was the cost of scaffolding on your project and what type was it?
Typical cost £35-60/m2 for traditional scaffolding.
Why our cavity trays becoming more expensive?
Cavity trays now need to be stainless steel so they are non-combustible.
You mention that you have an understanding on the different choices of facades that can be used for high rise and low buildings. Please explain which facades are commonly used in both cases and why.
Low rise :- Traditional as lower cost and less need for construction to be lighter
High Rise : - greater cost on foundation, SFS system will reduce load bearing capacity moving down the structure
What is corium brick slip cladding?
A brick slip system which uses a vertical rail system to attach the bricks to. Typically costs around £700/m2 for a through wall construction.
What is the cost difference between SFS and traditional brick?
Traditional brick - full wall build up (£450-500/m2).
How did grenfell change the way facades are built?
No combustible materials to buildings over 18m
RICS have an EWS Process
- appointed fire professional carries out risk assessment
- Looks at new / existing properties
- Valid for 5 years
What is a shelf angle in terms of masonry support and an expansion joint?
A shelf angle is a structural steel member that transfers the dead load of the brick back to the building frame. An expansion joint should be placed to prevent cracking.
Why would you recommend using an SFS over traditionally constructed wall?
Programme / Prelim benefits with concurrent fit out and external wall
Foundation and frame implications
No wet trades
What is the cost difference between traditional and SFS?
Around £200/m2 and fairly cost neutral when considering prelims
What is the cost for the blockwork and SFS element?
Blockwork £40/£50 /m2
SFS £80 /m2
Can you build up a rate for an brickwork facade?
£45/m2 brick £135/m2 Cavity Tray, Brick Ties, Fire barrier £50/m2 Insulation £70/m2 SFS £100/m2 for forming openings for glazings
What other features on the facade?
Stone banding @ E/O £150/m2
Projection features
Is off site construction more expensive, and does it save time? Also, does it have better quality?
Cost - typically more, specialist built and install on site
Time - quicker as constructed off site whilst other activities can occur
Quality - better quality, more space, less trades, carried out by specialists off site
How did you calculate the cost difference in the prelims with regards to SFS vs blockwork?
Mace logistics were able to advise that using SFS would make a saving to the overall prelims of 2 months
Can you tell me about what forms of modern methods of construction you are aware of.`
Modular construction Bathroom Pods 3D Printing Modular grids (internal walls) Minimise unit types
What ways can buildings be mechanically ventilated?
MVHR
Air Handling Unit
What are green / brown / blue roof?
A green extensive roof is planted for ecological and aesthetic purposes.
A brown roof is to mirror as best as possible local ecological conditions
A blue roof is onethatstoreswater.
What allowance would you typically make for floor finishes on your projects?
£80/m2 in units
£60/m2 communal areas
What is the floor build in a unit on one of your projects?
225mm slab
10mm Acoustic layer
70mm screed
15mm finishes
What was the cost difference between steel partition and blockwork?
£50/m2 blockwork (just blockwork)
£75/m2 SFS w/steel mesh
What would you allow for internal walls at a £/m2?
£60/m2
£5 E/O for moisture board
What type of finish would you expect for the floors on your project?
“Vinyl flooring
Carpel Tiles (communal)
Laminate
Carpet”
How was your project heated?
“Water tank heated by Low Temp Hot Water
CHP
Ground / Air Source heat pump”
What is the difference between an air source heat pump and ground source heat pump?
“ASHP relies on air to provide heat, through a heat exchanger, refrigerant is heated
GSHP uses natural heat from the ground to provide heat, through the heat exchanger”
What is an air source heat pump?
“1. Air drawn in from outside
- Air passes through heat exchanger
- Heat transferred to refrigerant from liquid to gas
- Passes through compressor heating temperature
- LTHW runs through ASHP which is heated by refrigerant”
What is an ground source heat pump?
“1. Buried pipes beneath ground with anti freeze
- Absorbed heat transferred to refrigerant
- Heat transferred to refrigerant from liquid to gas
- Gas passes through compressor heater temperature
- LTHW runs through ASHP which is heated by refrigerant”
Talk me through the savings you were able to make on the SFS vs Blockwork on the facade?
SFS £750/m2 = £5.6m
Blockwork £550/m2 = £4.4m + 3 months of prelims = £1m = £5.4m
3 month quicker construction led to the client accepting this option.
Additionally, labour rates for bricklayers are high due to a shortage
Talk me through the savings you were able to make on the blockwork vs SFS w/steel mesh to the internal walls?
3000m2 of area
SFS
£100/m2 +
£40/m2 for steel mesh = £420k
Blockwork
£50/m2
+ 3wk prelims = £240k (£80k / wk)
Overall £30k difference but client opted for 3 wk quicker construction
Shortage of bricklayers left unknown on costs
How is a steel frame constructed?
Steel columns will be cast into the slab
Installation of universal beams
Beams run across the upper floor area for floor finishes
Purlins to run across the roof
Accessories to fix and tie the frame together
What are the benefits of MMCs?
Better quality
Quicker construction
Less labour intensive
Less environmental impact
What is the process for RBP?
Form Pile Mat Mobilisation Excavation / disposal Secure excavation w/steel casing / bentonite Insitu conc Rebar Cut piles Test piles
What are the pros and cons of SFS?
Pros Lighter frame Programme benefits Concurrent fit out / facade Prelims savings
Cons
More expensive
Limited suppliers
Fire resistant barrier installed to facade
What other elements are impacted by cladding?
Structure
Foundation
M&E
What are the members of a steel frame?
Beams, Columns, Purlins, Cladding rails, erection, anchors
What performance considerations were made on the window options?
Aluminium
More durable
Holds more weight
Greater acoustics
Material more expensive
Composite
Meets performance requirements
Cheaper
Maintain aesthetics
Both had life expectancy of 50 years
Aluminium more expensive to repair
What life cycle costs were considered when you carried out the window?
The supply chain was able to confirm that Composite will have a longer lifespan (if engineered timber)
Replacement of glass is every 15 yrs
Both window types are similar cost for damages
