Construction Technology Flashcards
(145 cards)
1
Q
What are the RIBA Plan of Works?
A
- The RIBA Plan of Works provides a framework for the management and design of building projects.
- This ensures that all information is gathered before moving to a new stage avoiding costly errors.
Stage 0: Strategic Definition.
Stage 1: Preparation & Brief.
Stage 2: Concept Design.
Stage 3: Spatial Coordination
Stage 4: Technical Design.
Stage 5: Construction.
Stage 6: Handover.
Stage 7: Use of the building.
2
Q
Can you tell me the different types of structural frame construction you are aware of?
A
- Concrete frame construction.
- Steel frame construction.
- Timber frame construction.
3
Q
Concrete Frame: What are the respective benefits in terms of time, cost & quality?
A
Time:
- When poured in situ this increases time /labour costs.
Cost:
- Relatively consistent price.
- No additional cost for fire safety.
- Ongoing maintenance /repairs increasing lifecycle cost.
Quality:
- Naturally fire resistant.
- Limitations for open spans
- Lacks compressive strength (High compressive strength)
4
Q
Timber Frame: What are the respective benefits in terms of time, cost & quality?
A
Time:
- Prefabricated and erected quickly on site.
- Lead in times for off site manufacture.
Cost:
- Generally cheaper than steel /concrete.
Quality:
- Easily adaptable.
- Requires fire protection.
- Vulnerable to decay /termites if not maintained.
5
Q
Steel Frame: What are the respective benefits in terms of time, cost & quality?
A
Time
- Quick to assemble (occupied sooner)
- Lengthy lead in times (reliant on foreign imports)
Cost
- Cost of steel can fluctuate.
- Usually cheaper than reinforced concrete
Quality
- Durable / high strength to weight ratio
- Suitable for open plan design
- Corrosion risk if not maintained
- Requires fire protection; intumescent coatings.
6
Q
Sustainability comparison of structural frame solutions?
A
- Steel uses high embodied energy for manufacture.
- Concrete often uses locally sourced materials and is 100% recyclable.
- Timber offers greater insulating properties.
- Steel and concrete are both 100% recyclable whilst only 50% of a tree can be used for timber.
- Timber encourages deforestation although it can be argued that this encourages the planting of more trees.
7
Q
What would you consider when choosing a structural frame solution?
A
Programme Requirements: Steel /timber quicker to erect on site than concrete.
Clear span requirements
Fire protection requirements: Although steel is not combustible; steel requires protection against heat. Concrete is naturally fire resistant.
Height of the building: Timber framed buildings are restricted in height due to fire protection.
Site logistics: Delivery of prefabricated materials (timber /steel).
Foundation design: Cost of foundations may be considerably more for concrete structures.
8
Q
What are the different foundation types you are aware of?
A
- Raft foundation
- Strip foundation
- Pad foundation
- Pile foundation
9
Q
What is a raft foundation - when would you use this?
A
- Spreads the load over a large base and reduces the load per m2 of the area.
- Used for lightly loaded buildings on sites with poor soils.
- Heavy loads can cause the raft to move sideways as raft foundations are not very deep.
10
Q
What is a strip foundation and when would you use this?
A
- Strip foundations require a continuous excavation to support the perimeter and internal walls.
- Suitable for most subsoils and a light structural design.
11
Q
What is a pad foundation and when would you use this?
A
- Pad foundations provide a base for reinforced concrete or steel columns.
- Formed by making an isolated excavation in the shape of a square or rectangle.
- Spreads the load to a layer of bearing soil or rock below.
- They are common on large purpose built structures such as industrial units or other commercial buildings.
12
Q
What is a pile foundation and when would you use this?
A
- A series of columns inserted into the ground to transmit the load of a structure to a lower level of subsoil.
- Used where no suitable foundations conditions are present near ground level or if there is a high water table.
13
Q
What are the different types of pile foundation?
A
Sheet piles.
- A deep trench is excavated and concrete is poured in situ.
- Can form basement walls or retaining walls.
Bored Piles.
- An auger is used to excavate the soil and then concrete is poured in once complete.
Pre-cast piles.
- Piles are and hammered into the ground.
- Often favoured due to the high noise levels associated with installation.
14
Q
Why is it important to obtain planning permission and building regulations?
A
- Breach of law.
- Could be issued an enforcement notice to remove /alter the works.
- Non-compliance with planning: The LA have the power to undertake the work themselves and recover the costs.
- Non-compliance with Building regs can lead to a fine /imprisonment.
15
Q
What is the Town & Country planning Act 1990?
A
Regulates development for the future of towns, cities and the countryside.
16
Q
What are the Building Regulations and why are these important?
A
Regulates building work for new and altered buildings:
- Safety
- Accessible
- Environmental considerations.
17
Q
What are British Standards?
A
- Publications by British Standards Institution (BS)
- Recommendations on minimum standards for materials, design, and construction practices.
18
Q
What are International Standards?
A
- Publications by International Organisation for Standardisation (ISO)
- Compatible with and compliment British Standards.
19
Q
The Avenue, Hull: How did the occupants need for wheelchair access influence your planning and decision process?
A
All the areas were designed to ensure accessibility for wheelchair users.
This included accessible and doorways, corridors, and turning spaces were wide enough.
20
Q
The Avenue, Hull: Can you give more detail on how you used Doc M on this project?
A
Approved Document M provides guidance on how to meet the accessibility requirements of the Building Regulations.
I used it to ensure all elements of the refurbishment design were accessible, including doorway widths and ramp gradients.
21
Q
The Avenue; What steps did you take to ensure compliance?
A
To ensure compliance with Approved Document M, every design decision was reviewed with this document.
Also, a building control officer was hired to inspect the work at key stages.
22
Q
How did you determine the correct clear opening width of accessible doors?
A
The clear opening width of the accessible doors was determined based on the regulations stipulated in Approved Document M.
It states that there should be a minimum clear opening width of 850mm for wheelchair access.
23
Q
What considerations did you have for entrance threshold requirements?
A
To ensure they were flush with the door to prevent tripping or difficulty manoeuvring wheelchairs over it.
I specified Doc M compliant thresholds and looked into the materials that would work best in making them not only functional but also aesthetically pleasing.
24
Q
How did you design and construct the ramps to all external doors, while ensuring the suitable gradience was maintained?
A
I used CAD to design the ramps to all external doors, taking into account the gradient needed for safe use by a wheelchair user.
Building Regulation’s Approved Document M was also consulted to ensure ramps were of a suitable gradient (1:15 – 1:20).
25
The Avenue, Hull: What challenges did you face during the project?
The biggest challenge was ensuring that all designs met the Building Regulations Part M standards.
I overcame this by cross-checking all my designs with the guidelines provided in Approved Document M.
The project did require unique solutions, such as installing ramps for wheelchair access, modifying kitchen layouts to be more accessible, and including accessible washrooms.
I also had to ensure that all doors were wide enough to permit a wheelchair to pass through.
26
The Avenue, What else did you consider when widening the doorways?
* The structure of the building where doorways required widening to loadbearing walls.
* I appointed a Structural Engineer to determine the walls load capacity.
* S.E then designed the lintels.
27
Should it not be in a surveyors level of competence to specify lintels?
The structure of the building was being altered and therefore outside my level of expertise to determine the walls load bearing capacity.
28
What bearing is required for lintels?
* Typically, a minimum of 150mm at either end.
* Span of less than 1.2m this may be reduced to 100mm.
* This can vary so I would check the manufacturers recommendations on all occasions.
29
What is Doc M of the building regulations?
Access to and the use of buildings.
30
What parts of Doc M did you include at Cherry Meadows?
Approved Doc M: Vol 1 – Dwellings
Section 3 – wheelchair user dwellings.
31
What other sections are in Doc M, Volume 1?
- Section 1: Visitable dwellings.
- Section 2: Accessible and adaptable dwellings.
- Section 3: Wheelchair user dwellings.
Section 1 is mandatory for all new dwellings unless one of the optional requirements in section 2 or 3 applies.
32
The Avenue, Hull - What were the clear opening width requirements?
Visitable Dwellings: 775mm
Accessible Dwellings: 850mm
Wheelchair User Dwellings: 850mm
Section 1 & 2 can vary dependent on clear passageway width – I would take this into consideration.
33
How would you measure the clear width opening of a door?
From the inside face of the door when open to the inside edge of the door frame.
34
What are the entrance threshold requirements under Doc M?
That the threshold is an accessible threshold.
35
How do you measure the gradient of a ramp?
Dividing the rise by the overall length.
36
What gradient of ramps are required in Doc M?
Gradient between 1:20 – 1:15
- Maximum lengths listed in Diagram 3.1 of Doc M (3)
- Clear width of 1.2m (of any door)
- Top and bottom landings must be provided.
37
What requirements are there for approach routes?
- Step-free approach: Level, gently sloping or ramped.
- Minimum clear width of 1.2m.
- Suitable ground surface.
- Illuminated. (dusk /dawn timers or motion sensored).
38
Height of light switches for a wheelchair user?
Between 900mm – 1.1m for ease of location /reach.
39
Wheelchair accessible sanitary fittings requirement (M3)?
- Wheelchair accessible basins /sinks should be wall hung.
- Typically, the sink rim would be 770-850mm above finished floor level.
- Level Access Shower Trays.
40
Eastbank: What was the purpose of your inspection?
This was a progress meeting for ongoing refurbishment works.
During the meeting I identified a gap to the kitchen fire door threshold where the thickness of floor covering had changed.
41
What type of property did you inspect in Lytham?
Residential supported living accomodation.
Large victorian building, cavity wall construction and suspended timber floor.
42
Eastbank; Why had the threshold gap of the kitchen fire door increased?
The threshold gap of the kitchen fire door increased due to a change in the floor covering, which was replaced with a thinner material (vinyl) than the original (tiled floor).
43
Eastbank; What tool did you use to measure the gap of the fire door?
I used a door gap gauge to accurately measure the increased gap of the fire door.
44
Eastbank; What standards did you refer to identify the requirements of fire door threshold gaps?
I referred to the guidelines provided by BS 8214: CoP for fire door assemblies (timber)
Note: BS 9999 (2017 Fire safety standard) states that threshold gaps for timber doors should be in accordance with BS 8214.
45
Eastbank; Who did you consult with about the increased threshold gap?
I consulted with the clients designated Fire Safety Engineer about the increased threshold gap.
46
Eastbank; What was your proposed solution for resolving the issue?
My proposed solution was to provide a surface-mounted drop-down seal to accommodate the gap between the door and threshold.
47
Eastbank; What were the recommendations given by the fire engineer?
The fire engineer recommended an integral drop-down seal as they would not accept surface mounted.
48
Eastbank; Who did you instruct to undertake the necessary remedial work?
I instructed the contractor to undertake the necessary remedial work which was subsequently signed off by the clients fire engineer.
49
Eastbank; What exactly was the remedial work that had to be done?
Installation of an integral drop down seal.
50
Eastbank; Was the change of floor covering approved in the design stage?
Yes; a Provisional Sum was included to allow for alterations to all internal doors following the installation of new floor coverings.
51
Eastbank; what were the threshold requirements identified in BS 8214?
Threshold gaps for fire performance and smoke control should not exceed 3mm at any point.
If not an FD30s (not requiring smoke control) the threshold gap should not exceed 8mm.
52
What is a drop down seal? How do these work?
Drop down seal is a device fitted at the base of the door to stop smoke and fire from passing through the gap between the door and the threshold.
It works through an automatic mechanism where the seal drops down when the door is closed and retracts back (up into the door) when the door is open.
53
What is an FD30?
Fire door able to resist integrity failure for 30 min.
44mm thick.
54
What is an FD60?
Fire door able to resist integrity failure for 60 min.
54mm thick.
55
What checks would you do to ensure a fire door is compliant?
Look for the certification:
Fire door manufacturers mark their doors.
Intumescent seals:
Seals should be fitted around the door or frame.
Check gaps:
If the gap between the door and the frame is between 2mm and 4mm all the way around.
Hinges:
Fire doors should be fitted with at least 3 hinges. The hinges should be CE marked and fire rated to the same standards as the door.
Fire door closure:
It is essential that a fire door ‘latches shut’ when closing.
Fire Door is Clearly Marked:
All fire doors should have clear signage fitted.
56
How could you tell the difference between an FD30 and FD60?
Thickness of the door.
FD30: 44mm
FD60: 54mm
57
Winckley Square: What factors did you consider when choosing to recommend the installation of dormers?
- Durability and low maintenance costs of uPVC windows.
- The excellent insulation qualities of timber frames
- The aesthetic appeal of dormers in enhancing the overall building design.
58
Winckley Sq: Can you explain how you used Part L during your design process?
This guided my decisions on:
- Insulation
- Efficient energy use
- Appropriate glazing
59
Winckley Sq: How did the dormer interlink with the existing structure?
The new timbers were fixed to the existing window frame.
The timbers were designed by a structural engineer which was a requirement by the approved inspector.
60
Winckley Sq: How did you know if there were any issues with the structure of the windows?
The frame itself couldn’t be seen until the windows were removed.
Once removed, I inspected the site and did not identify any signs of deterioration, dampness, cracks, warping etc. to cause concern.
61
What building regulations were required for the dormers at Winckley Sq?
- Part A: Structure
Provided construction details for the dormers to include S.E calculations.
- Part C: Site preparation and resistance to contaminants and moister
Condensation risk and vapour control measures for dormer cheeks and roof.
- Part L: Conservation of Fuel and Power
U-value requirements for; cheeks, roof and windows.
- Part F: Ventilation (trickle vents)
- Part K:
62
What are the u-value requirements for a dormer?
Roof: 0.16 (maximum)
Cheeks: 0.18 (maximum)
Windows: 1.4 (maximum)
63
How are windows fixed to the frame?
Fixed through the uPVC frame into the timber structure.
64
What flat roof structures are you aware of?
Cold roof
Warm roof
Inverted roof
65
Whats the main difference between the roof structures (cold, warm, inverted)?
Location of where the insulation is installed.
66
What is a cold roof structure?
- Insulation is located above ceiling level.
- Insulation inserted between the roof joists with vapour control layer beneath.
- Minimum 50mm air gap above to allow for cross ventilation.
- Suitable decking (plywood /OSB) secured over the joist and finished with waterproof covering.
67
What are the advantages /disadvantages of a cold roof structure?
Advantages:
- Low impact insulation doesn’t affect the profile of the building.
Disadvantages:
- The timberwork sits right up against the roof covering and is therefore insufficiently protected against temperature variations.
- This makes the entire roof construction much more liable to expansion and contraction, which may cause the roof covering to tear or burst.
68
What is a warm roof structure?
- Insulation is located on top of the roof deck with waterproof membrane on top.
- A vapour control layer is placed under the insulation to reduce the risk of condensation as the ceiling or roof void is at a similar temperature to the roof.
69
What are the advantages /disadvantages of a warm roof structure?
Advantages:
- Extended lifespan because the entire insulation material and roof construction are protected from external influences.
- Less sensitive from expansion and contraction.
- Less risk of cold bridge.
Disadvantages:
- Design constraints due to increase in height.
70
What is an inverted roof structure?
- Insulation placed on top of the waterproof membrane. *
- No vapour control is needed.
- The roof void and deck are maintained at similar temperature to the room.
- The insulation protects the membrane from damage but must be anchored down.
- This roof construction is sometimes used for roof terraces and for flat roofs with heavy foot traffic.
71
Winckley Sq: Why was a warm roof not suitable?
- The height of the dormer head would have increased considerably close to the roof line.
- Would have looked out of proportion to the size of the dormers.
- Not ideal considering the aesthetics due to the conservation area.
72
What’s the purpose of an air vapour control layer in a roof deck?
- A vapour barrier installed on the warm side of the insulation (room side).
- Restricts the flow of warm moist air from entering the structure.
- Protecting from damp /mould.
73
What is a cold bridge?
- A cold bridge is created when there is a gap in the insulation or if materials that are poor thermal insulators come into contact, allowing heat to flow through the path created.
- An additional insulating component, called a thermal break can be introduced. (such as insulated backed plasterboard)
74
Cherry Meadows; What were the sustainability goals set by the client?
The client's sustainability goals were to achieve an EPC rating of a C.
This was focused on reducing energy consumption, lowering operational costs, and improving comfort for building users.
75
Cherry Meadows; How did you determine the cost-effectiveness of adding insulation to the existing floor structure?
I considered the wider scheme of works - the property was vacant (no disruption to occupants) and the floor coverings throughout were being replaced.
Given the energy improvement to provide insulation to the suspended floor I determined this would have been the best time to install.
76
Cherry Meadows; What factors were considered in researching various insulation systems?
In researching various insulation systems, factors were considered such as:
- Cost
- Performance
- Durability
I considered PIR boards. However, this approach was not ideal, due to the inflexibility of the insulation material and its inability to enable vapour to be absorbed and gradually dispersed.
I therefore, chose a mineral wool as a more flexible solution.
77
Can you elaborate on the importance of cross flow ventilation for the sub-floor?
Cross flow ventilation is very important for the sub-floor as it prevents the accumulation of moisture which could lead to issues such as timber decay and pests.
78
Cherry Meadows; What were the challenges in relocating electrical cables fixed to the joist?
The main challenge in relocating electrical cables fixed to the joist was ensuring minimal disruption to the electrical supply.
79
Could you provide more detail on your sketch of the suspended timber floor construction with proposed insulation?
From the ground level, there is:
- ventilation space
- Breathable membrane draped up and over the joists to create a cradle to support the insulation. (preventing drafts)
- 150mm Mineral wool laid between the joists.
- Airtight vapor control membrane laid over the top (preventing moisture and warm air escaping from the warm interior to the cold crawl space).
- Tape seal the interface between the floor and wall.
- New floorboards sealed and a vinyl floor covering installed.
This provided a fully insulated floor that was air tight, breathable and maintained drying capacity to protect against condensation risk.
80
Cherry Meadows; What considerations were made regarding future maintenance of the new flooring system?
To provide an access hatch to access service /future maintenance.
81
Cherry Meadows; Why was a breathable membrane installed beneath the insualtion?
The wind tight breathable membrane inhibits heat loss.
This also allows any moisture within the joists to disperse preventing the risk of damp, mould and rot.
82
Cherry meadows; why were the cables removed from the floor joists?
Electricity cables give off heat when in use and may overheat where they are covered by thermal insulation, increasing the risk of short circuit and fire.
I considered this during the design phase but the property was having a full internal re-wire.
The cables were dropped from the upper level during the re-wire.
If attached to the underside of the joists a higher capacity cable would generated less heat from the same current.
83
What are the u:value requirements for floor insulation?
Part L sets out the minimum U:Value requirements:
- Refurbishment: 0.25 (150mm of mineral wool required)
- Extension: 0.22
- New Build: 0:11
84
Are you aware of design guidance in relation to flat roofs?
BS6229: Flat roofs with continuously supported flexible waterproof coverings
85
Whats the purpose of BS8214?
This British Standard gives recommendations for the:
- Specification
- Installation and
- Maintenance of timber-based fire doors.
86
How did you use the fire door gauge?
Inert the measurement gauge until a snug fit between the bottom of the door and threshold.
Measure internally from the pull side.
87
What are the requirements for fire door gaps under BS8214?
Side and top of the door: Between 2mm and 4mm.
Threshold: 3mm for fire and smoke /8mm-10mm for fire (in accordance with the fire door manufacturers installation instructions).
88
How do drop down seals works?
When the door is closed, the seal lowers automatically due to a release mechanism.
This provided a seal to prevent the spread of smoke and fire.
89
Were the drop-down seals tested?
Yes the product was certified by CertiFire with testing records /data sheet info reviewed by the clients fire engineer.
90
What are the requirements for a ramp under Doc M?
- Gradient between 1:20 – 1:15
- Each flight has a clear width of 1.2m
- Top and bottom landings provided to each flight.
- Landings must be level and provide a minimum of 1.2m clear of any door swing.
- Approach routes must be illuminated, level and 1.2m minimum width.
91
What are the requirements for handrails on ramps?
Approved Document K lists the requirements of handrails for ramps these are:
- Ramps 600mm or less in height do not need handrails
- Handrails positioned at a height of 900mm to 1m above the surface of the ramps.
- Handrails must give firm support and allow a firm grip.
- Ramps more than 1m wide provide a handrail on both sides.
- Ramps less than 1m wide provide handrail on one or both sides.
92
What is a U:Value?
Measures how quickly heat will travel through the material /building element.
93
When were cavity walls introduced and what was the purpose?
Since the 1920’s – inner leaf of blockwork and outer leaf of brick stabilised with wall ties.
The internal blockwork carried the load of the upper floor and roof.
The external brick provides additional stability and protection from the elements (damp penetration).
94
Bloomfield; How did you determine the additional loading from the bath would be suitable for the existing floor?
I am aware that beam and block flooring can typically hold up to 600kg depending on the build up.
- The overall weight of the bath was 100kg (empty)
- Maximum occupant weight of 150kg.
I provided this information to the structural engineer who confirmed the loading would be suitable for the beam and block floor.
95
Bloomfield; Did the rise and fall /adjustable bath require a power supply?
The bath was connected to the power supply via a cord connected to wall-mounted outlet (splashproof)
A GFCI (ground fault circuit interrupter) was included with an accessible switch near the bathtub.
96
What is a circuit breaker and how do these work?
They are designed to shut off electrical power in the event of a fault.
97
Bloomfield; How was the rise /fall bath drained?
Through the wall and into the mains (combined) drainage.
98
What is combined drainage and how did you identify this?
A single pipe collecting rainwater and wastewater.
Commonly found in houses built before 1970.
Note: Separate system directs wastewater to a treatment plant and rainwater to a natural water source.
99
Can you describe to me a beam and block floor build up?
- An inverted ‘T’ beam is installed typically 150mm.
- Infilled with concrete block
- Insulation laid over the top
- Vapour Control Layer
- Screed /tounge & grouve ply wood flooring
- Floor covering
Note: the concrete is suspended with telescopic air vents beneath to prevent to remove moisture and prevent any build-up of ground gases (radon /methane).
100
What are the benefits of a beam and block floor?
- Fire resistance
- Unaffected by damp, rot or vermin
- Quick to install.
- Durable
101
Bloomfield Road; Were any hoists required for the specialist bathroom?
Yes, specialist hoists were specified by the occupational therapist.
- I reviewed the manufacturer's specifications and identified the required loadings.
- A structural engineer was appointed to assess the existing timber ceiling joists and provided a design.
- This included for 2 additional joists at the hoist support position as per the CE design.
102
Was a fused spur required for the hosit and if so could you explain what this is?
Yes.
A fused spur is used to provide means of isolating the circuit.
They are particularly useful where access to the appliance is not easy such as the hoist.
103
Can you explain the build up of timber frame construction from the outside in?
- Cladding material or brickwork: protecting the timber frame.
- Flexible wall ties: to stabilise the outer leaf and allow for movement /shrinkage of the timber frame.
- 50mm Cavity between brickwork and sheathing.
- Cavity barriers: provided to all junctions (walls /floors), window /door openings and at 8m centres.
- Plywood sheathing nailed to the timber fram deforming from wind load
- Timber frame made up of studs and plates
- Insulation between the frame
- Vapour control layer (polythene)
- Plasterboard
104
What foundation type would be suitable for a timber frame building?
Typically a stip foundation.
There is a DPC laid beneath the sole plate protecting the structure from rising dampness from the substructure (blockwork or concrete).
Sole plate often fixed with galvanised straps to avoid penetrating the DPC.
105
What is a cavity tray?
Fitted directly above an opening to to divert water within the cavity out through weep holes through the external skin.
106
What was the construction of the extension at Bloomfield?
- Suspended concrete beam and block floor.
- Cavity walls
- Pitched roof with pre-fabricated trussed rafters.
- Concrete tile roof covering.
107
How did you specify the fixings for the grab rails?
I considered the structure of the supporting walls and fixings required.
I consulted with the fixings manufacturer ‘Fisher’ and specified a concrete screw anchor suitable for concrete block walls (aerated concrete block used).
108
How does a cold deck roof differ from a warm deck roof?
The location of the insulation.
- Cold deck insulation is beneath the roof deck with a minimum 50mm air void between for cross flow ventilation.
- Warm deck insulation is above the roof deck with a vapour control layer between the deck and the insulation.
109
How is power distributed in a building?
- Mains power /distribution board
110
What's the difference between a single phase and three phase electricity supply?
A single phase supply is commonly used for residential homes where loads are minimal such as lighting and heating.
Three phase units are typically found on commercial buildings to accommodate higher loads. If you require two or more electricity meters then you need a three phase supply.
111
Can you explain to me what modern methods of construction are?
Modern methods of construction focus on off-site construction techniques.
This approach provides benefits such as:
- Speeding up construction time
- Reducing labour costs
- Eliminating waste
- Improving quality (manufactured in a controlled environment)
112
Give me an example of modern methods of construction?
Prefabrication of timber frames.
The frames are manufactured off-site, in a controlled environment. This reduces construction time and material waste.
113
What is air permeability?
Air permability relates to airtightness of the building to limit heat loss through air flow and preventing air infiltration (cold draughts).
Measured by an air leakage test.
This results in:
- Increase in energy use
- Heating systems not meeting comfort levels
- Cold draughts
- Reduced element U-values
- Potential emission of polluted air.
114
Cherry Meadows: Where did you review the requirements for sub floor ventilation?
Approved Document C: Site Preparation and Resistance to Contaminants and Moisture.
115
Cherry Meadows: What requirements for sub floor ventilation did you advise your client of?
- Air bricks to be at least 75mm above hard and soft landscaped areas (to reduce risk of obstruction or flooding).
- At least 150mm to the underside of the suspended timber floor /insulation.
- Ventilation bricks located on two opposing external walls to create a free path for air ventilation.
- Ventilators should be spaced at no more than 2m centres and within 450mm of the end of any wall.
116
Cherry Meadows: Why is it important to provide sub-floor ventilation?
- To allow free movement of air preventing condensation /dampness to the floor structure.
- Air ventilation also provides dispersal of ground gases, including Radon.
117
Cherry Meadows: What did you advise your client of the risk of the shrubbery to the rear of the property?
- This would prevent adequate cross flow ventilation to the sub floor.
- Allow rainwater to enter the under floor void.
- High risk of condensation /rot to the timber floor structure.
118
Cherry Meadows: What risks did you advise your client of relating to insulating the suspended floor?
Increased risk of condensation.
I advised the client to cut back the shrubbery to the rear elevation to ensure adequate cross flow ventilation.
There was a ‘Breather membranes' installed beneath the insulation to prevent any water vapour becoming trapped in the floor structure. (from any damp in the timbers).
119
Cherry Meadows: How did you ensure the VCL wasn’t breached when installing the flooring?
The floors were laid with plywood which compressed the VCL between timber supports and plywood sealing any minor nail holes created from fixing.
If the timber support was missed at any point then that hole would need to be sealed with VCL tape.
120
Whats the process of pre fabricating concrete?
- Moulds are used to shape the concrete into the desired shape.
- The concrete is poured into the moulds.
- It is allowed to cure for a specified period of time, typically 28 days.
- During this time, the concrete gains strength and durability
121
How does a solid wall function differently to a cavity wall?
Solid walls will hold moisture from rain /snow until it can be released in a dry period without penetrating the inside of the building /or causing damage.
Cavity walls have an external skin to protect the inside of the building from dampness which is tied to the internal skin with wall ties to provide stability from wind loads.
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Eastbank Road: Why was the fire door not considered when changing the floor covering?
There was a Provisional Sum included for any alterations required following the change of floor coverings throughout the property.
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What is a fire engineer?
Fire Safety Engineers make recommendations about building design and materials to prevent fires starting and spreading.
They visit construction sites to oversee works and liaise with local authorities, construction professionals and architects about fire safety.
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Cherry Meadows; How did you inspect the floor joists?
- Inverted Head and Shoulders inspection via a hatch in the floor.
- I also used a selfie stick to take photographs of the joists.
- Once the floor was exposed I revisited site to confirm my findings.
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The Avenue: How did you calculate the requirements for structural lintels to widen the doorways?
A Structural Engineer was appointed to assess the structural loadings - any works that alter the sturcutre of a building would be outside my level of competence.
I am aware requirements for lintels are listed in Approved Document A and also can be found in the lintel manufactuers technical instructions.
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What does Approved Document A say about lintels?
The bearing length must be 150mm or greater.
Where the bearing has a clear span of 1.2 or less the bearing length may be reduced to 100mm
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The Avenue: Did the ramps require Building Regulations?
Yes.
Altering the entrance is classed as a **‘material alteration’** of the building which is notifiable to the local authority.
Works that affects building regulation requirement M (access to and use of buildings).
Additional guidance is also provided in Approved Document K: Protection from falling, collision and impact.
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The Avenue, Hull: What was the ramp constructed of /how did you prevent the ramp breaching the DPC?
Cast in situ concrete.
The edges of the ramp was offset approx. 300mm from the external walls to prevent breaching the damp proof course.
The landings abutting the entrance door was designed to direct surface water away from the threshold usining drainage slots and channels.
The design of the door threshold itself – included a sill and water bar (threshold unit).
Threshold to have a maximum 15mm upstand / have a minimum 45mm projecting sill to shed rainwater away from the interface with the waterproofing layer
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If a concrete ramp cannot be offset from a wall; how would you prevent the DPC being breached?
The damp proof course should be altered to maintain the 150mm distance to the top surface of the ramp.
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The Avenue: What was the floor construction and how did you maintain ventilation?
Suspended timber floor.
The wall ventilators was extended by ducting under the ramp.
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Winckley Square: What risk of thermal bridging did you consider?
Thermal bridges can lead to a heat loss.
Thermal bridging increases the risk of surface and interstitial condensation.
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Winkcley Square: How did you mitigate thermal bridging of the cold roof structure?
I included insulated backed plasterboard into the design to provide a thermal break.
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What advise would you give to a client when they are looking to choose between a steel and institu concrete design?
- Time
- Cost
- Quality
Consider open span requirements and foundation design.
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What considerations would you make if a piled foundation was required?
- Access restrictions for the rig.
- Noise disruption for the local area
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When would it not be suitable to install insulation to a suspended timber floor?
Where there is existing evidence of:
- Damp /rotten timbers (not exceeding 20% moisture content)
- Lack of cross flow ventilation /blocked floor vents.
- Where the depth of insulation would restrict the cross flow ventilation.
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How was the insulation installed to the suspended timber floor?
The floor boards were raised in sections and insulation installed from above.
It wasn’t practical or safe to install from beneath.
The floors were lifted in sections for the safety of operatives.
New vinyl floor covering was to be installed anyway so the floor was ply lined.
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What documents did you review when specifying the under floor insulation at Cherry Meadows?
- Approved Document C: Site preparation and resistance to contaminates and moisture
- Approved Document L: Conservation of fuel and power (0.25).
- BEIS Guide to best practice: Retrofit floor insulation (Business, Energy & Industrial Strategy)
- PAS 2035 Retrofit standard framework for domestic buildings
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Were there any pipes passing through the insulation – how were these dealt with?
The pipework /cables were sealed to the membrane with an airtight grommet.
Water pipes were insulated with lagging to prevent from freezing.
Note: Gas pipes are not insulated!
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Cherry Meadows; What depth was the joists and why would you measure this?
150mm x 50mm (6x2)
I measured the depth of the joist to ensure the cross flow ventilation wasn’t reduced or restricted by the insulaiton.
This was to also ensure sufficient insulation was installed.
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Why are air bricks important for suspended timber floors?
Providing a circulation of fresh air keeping the timbers dry and preventing decay.
The vents are installed at opposite ends of the external walls to maintain adequate cross flow ventilation to the timbers.
141
Cherry Meadows you’ve mentioned upgrading the heating system. What was the existing system and what options did you consider to suggest a new system?
The existing system was a gas combi boiler that was approximately 10-15 years old.
The system was a like for like swap with a more efficient A-Rated gas combi boiler.
- Project budget wouldn’t allow to change the whole system.
Note: Combi – don’t have header tank or cylinder. Larger properties may be not ideal due to pressure
Direct system (system boiler) – Tank storing hot water and the cold water fed directly through mains.
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Winckley Square: You’ve mentioned 100mm joists – what was the spacing between these and what grade of timber was used?
400mm centres
Grade C24
Timbers designed by Structural Engineer as per Building Control officer requirements.
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Whats the difference between C16 and C24 timber?
The main difference between C16 and C24 timber is their strength and load-bearing capacity.
C24 timber has a higher minimum strength than C16 timber, meaning it can handle a heavier load.
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You’ve mentioned different steel frame solutions – can you give me some different examples of steel frame roofs you might come across in industrial buildings?
- Steel portal frame
- Steel truss design (various types)
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What is an EPC and what is the purpose?
Energy Performance Certificate required when a building is built, let or sold.
The EPC will inform potential buyers or tenants about the energy performance of a building.
They can then consider energy efficiency as part of their investment to buy or occupy that building.
