Construction Tech Flashcards
What are the RIBA stages of work?
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.
what are the 8 stages of RIBA
0 - Strategic definition.
1 - Preparation and briefing.
2 - Concept design.
3 - Spatial coordination.
4 - Technical design.
5 - Manufacturing and construction.
6 - Handover.
7 - Use.
Strategic Definition
the client’s business case and strategic brief are assessed to ensure they have been properly considered’ and the scope of the project is defined.
Prep and Briefing
developing the information that the design team will need to commence the design process at Stage 2
Concept design
represents the design team’s initial response to the client’s requirements. Concept design generally takes place after feasibility studies and options appraisals have been carried out and a project brief has been prepared.
Spatial Coordination
is fundamentally about testing and validating the Architectural Concept, to make sure that the architectural and engineering information prepared at Stage 2
technical design
The technical design stage (sometimes referred to as ‘design’) develops the design in sufficient detail for co-ordination to be completed and enables packaged, production information to be prepared which can be passed to the contractor and their supply chain to construct the development.
Manufacturing and construction.
The main contractor will produce working and fabrication information documents at Stage 5 to enable coordination of the full design including manufacturing of off-site materials and components.
Handover.
The building contractor will hand over documents including a building owner’s manual and the health and safety file. For the design and build teams, Stage 6 can still involve practical tasks, such as discharging planning conditions and rectifying defects.
Use.
The design team and construction team typically have no duties during Stage 7 of a project, but ongoing feedback is useful for future projects. Post Occupancy Evaluation services help fine-tune a building and inform future projects.
How are pad foundations connected to steel columns
Through holding down bolts cones and stancion plate
How are internal stud partitions formed?
- Head and base track
- Stud fixed at 600mm centres (plasterboard typical width 1200mm)
- Insulation between studs
- Pattressing
- Door openings formed
- Abutments, tees, fair ends
- Plasterboard
- Head detail (depends on frame)
What does the Building Safety act mean for construction?
For the construction industry, it means an overhaul in existing regulations, creating lasting change and makes clear how higher risk buildings should be constructed and managed to ensure that those who use them are safe and feel safe.
What updates were there on the 18th edition electrical guidance?
It is now a requirement to protect final circuits supplying socket-outlets with a rated current not exceeding 32 A using arc fault detection devices (AFDD) in Higher Risk Residential Buildings, Houses in Multiple Occupation, Purpose-built student accommodation and Care homes
What is and Arc Fault detection device?
AFDDs are protective devices installed in consumer units to provide protection from arc faults. They use microprocessor technology to analyse the waveform of the electricity being used to detect any unusual signatures which would signify an arc on the circuit
What did the tanking detail sign off require?
Product spec and details to be signed off by building inspector
What did the grouting process in Halifax involve?
metre by metre grid dill and grout of shallowing mine workings
What are the benefits of raft foundations?
The principal aim of a raft foundation is to spread the load of the building across the entire available surface area under the building. This reduces the stress on the ground below, providing a solid foundation that can accommodate ground movement whilst still maintaining structural integrity.
What are the disadvantages of raft foundations?
In some cases, large amount of reinforcement is required for raft foundation which increases the cost of project.
Special attention on raft foundations is required in case of concentrated loads.
If they are not treated properly, there is a chance of edge erosion.
Skilled workers are required to construct the raft foundations.
What are other types of foundations?
Strip
Trench fill
Raft
Piling
Why did you advise that a raft foundation was required for the modular building?
Required as advised by the modular build contractor for drainage and load distribution
Why is fire stopping required for certain partitions?
Fire rated partitions are required to ensure smoke and fire seal to maintain integrity
Why did you advise that partitions could be built to the underside of the ceiling?
Fire compartmentation could be maintained and cost saving and programme saving
What is MMC?
- Modern methods of construction
- Generic term to embrace all processes which reduce level of on-site labour intensity and delivery risk
- UK government has formally defined 7 types - structural (3D boxes, 2D panels, structural components, 3D printing), and non-structural (3D printing, pods & panels & components, smarter materials, better processes)
Can you provide some additional benefits of MMC (vs in situ)?
- Quality control
- less waste
- lots of government drive
- better management of embodied carbon
- easier transparency and resourcing in projects
- aid in programme
- safety on site
Some of the disadvantages of prefabricated units?
- Requires economies of scale to be worthwhile financially
- Limited funding in private sector
- Lack of trust and knowledge in new technologies
- Lack of control in delivery process
QS MMC considerations?
- Costs more, potentially working on different sites, prelims costs
- More suited to milestone payments, vesting certificates, advance payments, materials storage
- Small pool of MMC contractors, lack of benchmarking data available
Advise on time/cost/quality of different materials and methods of construction?
- On queenshill project, although higher upfront cost, longer life span and reduced maintenance and repairs costs, reduced programme
pcc planks
roof trusses
What to consider for life cycle costing? (LCC)
- Present value, life span, maintenance costs, cleaning and operation costs, discount factor
What is meant by life cycle costing?
- Accounting for relevant costs over defined period of time, considering total running costs, maintenance and repair for client to consider in long term use
What is meant by whole life costing?
- Broader scope than LCC - can include costs associated with income, externalities, land acquisition (non-construction costs)
What is the purpose of life cycle costing?
- Predict cashflow when building is in use
- Carry out options appraisal to decide which is better value long-term
What are the different levels of LCC estimates?
According to RICS LCC:
- Component level
- System level (discrete components combined to form a system)
- Element level (construction part performing same function)
- Cluster level (work package)
- Single asset / whole building level
- Multiple assets / portfolio/estate level
Can you provide examples of operational processes allowed for in life cycle costing?
[As per life RICS life cycle costing professional guidance]
- IT services
- Cleaning
- Rent
- Insurances
- Energy costs
- Local taxes and charges
Can you provide examples of maintenance processes allowed for in life cycle costing?
[As per life RICS life cycle costing professional guidance]
- Redecoration
- Periodic inspections
- Component replacement
- Unscheduled corrective and responsive
- Planned and preventative maintenance and component replacement
How do you consider operational and maintenance processes in life cycle costing?
- Consider operational and maintenance processes required
- Consider net present day value of costs
- Calculate annual equivalent value
- Consider how often components will need to be replaced / maintained (will usually state on product specification)
- Input the net present day value at these calculated frequencies over required number of years
What data do you use for life cycle costing?
- Sources from historical data - i.e. from facilities managers
- BCIS [life cycle costing]
- Modelling techniques to yield calculations (software)
- Data from manufacturers / suppliers / specialist contractors
What are O&M manuals?
- Operation and maintenance manuals
- Contains information required for operation, maintenance, decommissioning and demolition of a building
- Produced by contractor / sub-contractor, with supplementary info from designers (service engineer) and suppliers
What might be included in an O&M manual?
- Building’s construction details
- As-built drawings and specifications
- Instructions for operation and maintenance, including H&S info and manufacturers’ instructions
- Asset register of plant and equipment
- Commissioning and testing results
- Guarantees, warranties, certificates
- Requirements for demolition, decommissioning and disposal
Typical programme for new build structure?
- Site clearance
- Enabling works
- Site setup (prelims - could be 17-20%)
- Haul & access roads (inc)
- Setting out
- Excavation (machine - could be £5-15/m3 or £40-80/m3 breaking out; hand - could be £15-30/m3 or £50-100/m3 breaking out)
- Foundations (£ as above)
- Frame
- Cladding
- Roof
- Floors
- Services
- Finishes
- FF&E (very much depends on extent that
- Testing and commissioning
- Landscaping
- Snagging
Typical programme for existing structure?
- Enabling / facilitating works
- Frame alterations
[- Cladding - Roof
- Floors]
- Services
- Any RAF
- Finishes
- FF&E
- Testing and commissioning
- Landscaping
- Snagging
What is top down construction?
- Allows superstructure and basement to be built simultaneously. GF slab constructed, below ground excavated
- More expensive generally - specialist plant and complex methodology
What alternatives are there to top down construction?
Bottom up construction - Traditional method, basement and substructure elements constructed then working upwards. Simpler, but longer programme
What is a basement?
Storey below ground storey
3 types of basement construction?
- Retaining wall and raft (monolithic) - slab raft foundation, basement walls are retaining walls
- Box and cellular raft - similar to above, internal structure walls transmit and spread loads over raft, divides basement into cells
- Piled - main superstructure loads carried to basement floor by columns, transmitted to ground via pile caps, bearing piles (lots of columns going through basement)
3 methods of waterproofing a basement?
- Dense monolithic - designed and built to form watertight space using high quality reinforced concrete, needs strict control and good workmanship
- Tanking (i.e. polythene sheeting, bitumen, epoxy resin), applied internally/externally to provide continuous membrane to base slabs and walls. External better as this protects structure too
- Drained cavity - can be used for new / refurb work. Accepts small water seepage levels, collects and drains away. Inner non-load bearing wall to form cavity, floor laid to falls, moisture drains to sump, discharged direct
-> waterproofing solution often influenced by basement final use
Different grades for waterproofing basement?
- Grade 1 - some water seepage and damp is tolerable (i.e. car parks)
- Grade 2 - No water penetration acceptable
- Grade 3 - No dampness / water penetration acceptable (i.e. ventilated resi and commercial areas - homes, offices, shops)
Different types of foundation?
- Strip
- Pad
- Raft
- Piled
Typical considerations when selecting type and size of foundations?
- Building load
- Nature and bearing capacity of ground
- Structure type
- Cost
- Construction constraints (proximity to nearby structures)
Explain the suitability of different foundation solutions
- Strip - well-made ground with good load-bearing capacity, low load-bearing weight from structure
- Raft - poorly made ground with low load bearing capacity- spread load across entire building footprint
- Pad - well-made ground, for structures with high load-bearing points i.e. columns on steel frame
- Piled - High load-bearing, poor ground and tight sight conditions
Typical components in ext wall / foundation detail?
Strip foundation
- Concrete block foundation wall
- Rebar reinforcement
- DPC
- Air bricks
- Suspended / GF slab
- Backfilling
- Drainage
Why were piled foundations selected for your job at La Plata Grove?
- Poor soil conditions, soil not suitable to prevent excessive settlement. Raft wouldn’t have provided adequate support
What are piles?
- Series of columns constructed / inserted into ground to transmit structure load to lower level of subsoil
- Used where no suitable fdn conditions near ground level / high water table, poor bearing capacity of soil
Main construction methods for piled foundations?
- Bored piles
- Driven piles
Types of piles?
- Replacement - soil excavated to make the pile, relies on end-bearing more than friction (includes flush & percussion bore piles, rotary bored piles, continuous flight auger (CFA) and grout injection piles)
- Displacement - soil pushed aside to insert preformed pile, relies more on friction (includes preformed concrete piles, steel tube piles, partially preformed piles, driven in-situ)
Different ways piles transfer load to the surrounding ground?
- End bearing - transfer load through low-bearing capacity soil to strong stratum (rock/dense sand)
- Friction - frictional resistance between outer surface and soil in contact
- Settlement reducing - beneath central part of raft foundation to reduce differential settlement to acceptable level
- Tension (tall chimneys, transmission towers, jetties) - resist uplifting forces that may otherwise cause structure to be extracted from hydrostatic pressure, seismic activity or overturning movement
- Laterally loaded piles - bridge piers, tall chimneys, retaining walls
When would you use a bored pile? What’s the process involved?
- Build up areas with cohesive soils (i.e. clay) with requirement to go down 15m+
- Used where load requirement greater than CFA capabilities - larger diameter, greater depths
- Heavy duty crane with Kelly bar, concrete mixer truck and bentonite storage. Soil excavated, bentonite and casing inserted to stabilise, concrete pour with mixing truck and reinforcement cage, casing removed on completion
Bored pile vs CFA pile
- Bored piles have excavation and concrete pour done separately, crane + more substantial piling rig, larger diameter and greater depths, casing required
Advantages and disadvantages of precast piles?
Advantages
- Can be precast to required spec
- Any size, length and shape can be made in advance
- Driven into granular soil compacts adjacent soil mass -> bearing capacity can increase as a result
- Fast, neat and clean installation
Disadvantages
- Requires heavy equipment to handle and deliver
- Increased noise and vibrations
- Costly if piles are too short
Advantages and disadvantages of bored piles?
Advantages
- Any size / shape can be formed on site
- No risk of damage during delivery and handling
- Less vibrations and noise
Disadvantages
- Significant spoils generated - need to be handled
- Reliance and coordination on multiple trades (reinforcement, piling and concrete crews/suppliers
- Don’t improve bearing capacity of ground
QS problems regarding cost control with piling?
- End depth never a certainty
Cost difference between different types of foundations?
- Varies depending on thickness, material prices
- Piling cost approx £200-£250/m, could be on La Plata Grove cost was around £600-800/sqm (£30k per plot)
- Strip/trench foundations cost £250-£350/m, or £210-250/sqm, £11-13k per plot
- Raft foundations around £200-250/sqm, could have been £10-12k per plot
- I didn’t calculate pad foundations for this particular project but the cost could be £100-150/m3. Need structural engineer’s drawings for cost/m2
What is a raft foundation?
- Continuous slab extending over entire footprint of building
- Spread load of superstructure over large base, reduce load per sqm of area
- Useful in load bearing capacity soils and heavy individual column loads
- Solid raft slab / beam and slab raft - ground beam system and suspended PC concrete GF
What conditions are required where you’d expect a raft foundation?
- Lightly loaded buildings, poor soils
- Heavy loads can cause raft to move sideways (as it’s not very deep)
What is a strip foundation?
- Formation in strip of linear structure, spreading weight across total ground area (supports masonry)
- Suitable for most subsoils and light structural design
- Usually reinforced
What are pad foundations?
- Provide a base for reinforced concrete / steel columns. Usually constructed from reinforced concrete, square / rectangular on plan
How are foundations constructed?
- Setting out
- Excavation and disposal
- Relevant formwork
- Install rebar
- Concrete pour (/ drive in)
- Cut rebar / connect into slab
- Pour ground slab (after relevant reinforcement installed)
How to reduce / control moisture levels in a basement? (and how much would this cost?)
Archives
- Dehumidifier (£20-30/sqm)
- Pollution, temp and humidity sensors (£10-15/sqm)
- Replacing lighting with more energy efficient bulbs (£20-25/sqm)
- Air conditioning system (£30-40/sqm)
- Manual winches to heaters (£500/each)
- Leak detection sensors (£15-25/sqm)
[+ tanking]
Typical elemental cost?
£/m2
- Enabling works (£50-150/sqm)
- Substructure (exc basement) - £80-150 (inc basement £250-350)
- Frame and upper floors £300-450
- Roof (£300-£500)
- Stairs (£8-10k per storey)
- External walls (£500-800)
- Internal walls and partitions (£130-£200)
- Internal doors (£450-£2500 each)
- Finishes (£150-£300)
- FF&E (£90-£120)
- Services (£450-650)
Different types of internal walls?
- Timber stud (£50-80/m2)
- Metal stud (£80-110/m2)
- Brick partitions, depends on whether single or double skin (£70-150/m2)
- Block partitions (£60-90/m2)
- Concrete partitions (reinforced) £250-£350/m2
- Glazed walls £500-800/m2 - can be much more expensive with acoustic considerations
- Sliding partitions £2k/m, or £600-900/m2
- eo for curved work could increase costs by about 20-30%
- Manifestations £150-200/m2
What are the main factors that might affect the choice materials for internal partitions?
- Strength - if fixings required
- Level of transparency required
- Acoustic and fire rating
- Fixed / movable
- Thermal properties
- Door/window requirements
- Height
What is plywood?
Plywood = wooden material, made up of several sheets of thin wood. Less durable and easy to work with
What is plasterboard?
Plasterboard (aka gypsum) = material sandwiched between 2 thick sheets of paper, modern alternative to plaster (though usually tape and jointed too). Comes in large panels (say 1200m width) and easy to cut
Plywood vs plasterboard?
- Plasterboard = cheaper, easier to work with, fix, and install, easier to decorate, can be more fire resistant, better sound dampening properties, more versatile
- Plywood = lighter, stronger, more damage resistant (but more expensive to fix)
Why are manifestations required?
- Privacy
- Accessibility (see where windows / doors are) and prevent injuries
Manifestation regulation requirements?
- Glass doors and screens clearly defined on 2 levels (850-1000mm and 1400-1600mm above floor)
- Manifestation can take form of logo / sign at least 150mm high or decorative feature at least 50mm high
Acoustic benefits and limitations of different internal wall types?
- Stud - Can install insulation and plasterboard but stud itself doesn’t necessarily contribute to soundproofing
- Brick/block partitions - if two walls thick, can have insulation + dense blocks + acoustic plasterboard = very effective solution, but takes more space and more cost. Limited options if only single skin
- Glazed - thin wall, aesthetic, aids function of keeping meeting rooms visible but helping confidentiality of conversation, but may require thicker glass / more absorptive materials -> more expensive
- Sliding / folding walls - they can be made sound proof and aid with the flexibility of the space, however need to be closed fully (no gaps) to minimise sound travelling and is more expensive
How to make a wall more soundproof?
- Add high density material (i.e. acoustic plasterboard (higher density core), soundproof barriers)
- Insulation (between stud frames) to absorb sounds
- Curtains
- Acoustic clips - designed so noise that transfers through building structure can’t due to being separated
- Sealing edges of soundproof boarding and wall perimeter
- Acoustic putty
- Double thickness walls (expensive, hard to build, take up more space)
- Acoustic batts (reduce and absorb sound, cotton / fibreglass)
[- Expanded foam sprays are more for thermal insulation]
Partition build up?
- Head and base track
- Stud fixed at 600mm centres (plasterboard typical width 1200mm)
- Insulation between studs
- Pattressing
- Door openings formed
- Abutments, tees, fair ends
- Plasterboard
- Head detail (depends on frame)
How do you construct a glass partition?
- Glass fixed into frame (wood / steel)
- Glass placed in a rebate, secured with putty / beading
- Frame mounted between walls / columns required, usually secured with putty
Different types of balconies?
- Bolt-on - cantilevered off building or on open mesh deck, bolted onto building exterior with support system, say £7-12k each
- Juliet - full height glazing with railing, but no outdoor space, say £2-3k each
- Inset - constructed with the frame and structure- recessed into the facade of a roof / building, say £5-10k each
[- Roof terrace (minimises usable GIA - premium feature), cost depends on spec, build up can include waterproofing, decking structure, finish, access for services]
How to construct inset balconies?
.e. on DBE
- Build as continuation of slab and construct walls around it
- Waterproof membrane
- Thermal break
- Slab decking system (on adjustable pedestals)
- Concrete banding
- Fairfaced concrete finish (can be tiling, paving slabs)
Inset vs bolt on balcony?
- Inset generally cheaper (less balustrading, decorative details
- Bolt on can save on time
Factors affecting balcony choice?
- Cost
- Complexity of installation
- Location
- Size and design
