Flashcards in Construction Technology and Environmental Services Deck (63)
What is the sequence of operation of strip foundation?
Top soil removed
ground levels reduced
earth work support
Steel reinforcement and concrete laid
Bricks or concrete inserted (to conform with BS 5628 if below ground)
Superstructure transition at ground level.
DPC at 150mm above ground level
Cavity wall to be at least 50mm
Wall tie spacing at 900mm centres
What is piling and name and explain two types?
Series of columns inserted into ground to transmit point loads.
Used in soils with low load bearing capacity.
Loads are distributed different to raft or strip (large area distribution).
End Bearing Piles - transmit load to firm strata
Friction Piles - transmit loads to surrounding soil via friction
What effect does ACOP 8 have on projects?
Depends on the project.
Is building built prior the ban of asbestos?
Does the building require licensed or un-licensed Asbestos removal?
Both have the potential to inflate cost, licensed more.
If Asbestos is to remain in situ considerations need to be given training to persons accessing site.
What effect does Management in Construction have on cleaning windows?
Design specification should give consideration to safe cleaning (for instance cleaning from the inside). Or potential abseiling points.
Any remaining risk needs to be captured in a risk register.
What consideration were given to the approved document 'Structure' in regard to the replacement at Windward House?
Compared loading (old and new)
Reviewed O&MS and cross reffed with insulation in-situ.
The wholesale replacement would have been Kingspan closed cell insulation. This was significantly heavier than the existing open cell insulation and I am aware that an engineers inspection/recommendation would be needed to assess if strengthening measures were required.
What drainage provisions were required for Windward?
As the works turned into a patch repair remediation no drainage works were required. Although, I understand guidance is at
Document 6 - Drainage, hygiene and hot water storage, as well as relevant BS guidance.
For Windward, (Warm Deck) how did you prevent potential interstitial condensation?
Warm roofs have less chance of interstitial condensation than cold roofs.
Specifying adequate insulation and VCL should prevent air within voids reaching dew point.
What were the cost difference with the options put towards your client on Windward House?
Full roof remediation - $720,000
Patch repair - $170,000
Both exclude professional fees.
Why were the contract works for full roof remediation more expensive over patch repairs?
Full roof remediation required scaffold and canopy (longer time frame and associated risks).
For Windward, what was the difference in quality for patch repair and full remediation?
Full remediation included - material warranties, collateral warranties.
Patch repair did not have warranties on materials.
On Windward, Did you provide your client advise on the sensitivities of the works?
Yes, Major roof repairs would be significantly louder and risked the potential for water ingress if no canopy was used. This would be detrimental to the top floor tenants.
Are there any tests you can undertake to identify routes of water entry within a single ply membrane?
Dry Testing (sends DC current across membrane)
Can you explain advantages and disadvantages of timber frame over blockwork regarding time?
Internal finishes can applied earlier
Can be watertight quicker
More time consuming to lay
Greater degree of skill (longer procurement time)
Explain advantages and disadvantages of timber frame regarding cost?
Cost of materials is roughly the same albeit timber can yield lower costs as the installation time is faster.
Long term structural defects are common in my experience so the reducing of cost for construction may not be a long term benefit. Good standard of design or monitoring is crucial for both however.
Explain advantages and disadvantages of timber frame regarding quality?
Concrete block is fire resistant by default, although with appropriate spec timber can achieve appropriate levels of fire resistance.
Timber frames need quality materials, installation and weatherproofing to maintain longevity.
Timber frames need to be teated to protect against mould, rot and damp whereas concrete block work does not.
In brick walls describe sequence of operation for wall ties?
Spaced at 600mm centres at each 3 courses
Name some types of pointing?
Describe sequence of operation of a cavity wall?
Mass concrete foundation (depending on strata)
Bricks and blocks below ground (bs stand)
Cavity below ground filled with weak concrete (prevents earth moving pressure)
DPC 150mm above ground level
Note; cavity to extend 225m belo DPC
Wall ties at 900mm centres 450 apart.
Describe the sequence of operation of a solid floor on level site?
Insulated screed and floor finish
Solid concrete bed compacted over hard core
cavity wall to extend 225mm below DPC
weak cement in cavity below 225m to resist compressive pressure from backfill.
Describe the sequence of operation of a suspended timber floor?
Joists (at 400mm centres)
100mm thick concrete atop well compacted hardcore
Name two types of floor structures?
Suspended timber floor
Discuss the sequence of operation of a standard purlin roof?
Rafters at 400 centres
Purlin at 1600 centres
Collar fixed to purlin
Hangars stemming from collar to joists
What is a roof truss and what is its sequence of operation?
These are triangulated roof frames designed to give clear spans between the external supporting walls. They are usually prefabricated. (Study Page 398/399 in Chudley and Greeno)!!!!
What is a roof underlay?
barrier for wind driven rain between slates and tiles
What is the build up of a roof above the rafters on a typical timber pitched roof?
What primary legislation governs planning legislation?
Town and country planning act 1990
Planning (Listed Buildings and Conservation Areas) Act 1990
Explain Part 11.2B in relation to roof replacement?
For roofs which require replacement of 50% or more in the whole roof areas requires replacement in accordance with latest regulations.
Why did the riser enclosures need to comply with document part 11.2B? (Conservation with fuel and power)
They didn't because they were not habitable, of which i advised my client. However the justification to the enclosures was to ensure longevity to the control panels. If the internal temp was consistently dropping below to dew point interstitial condensation could have occurred. Appropriate insulation prevents this.
What did the feasibility assessment include for the roof remediation to Windward house?
Analysis of client requirements
Assessment of potential existing facilities (LW4 preliminaries)
Material Options and programme