Construction Technology & Environmental Services Flashcards
What impact do the Building Regulations and British Standards have on the design, construction and refurbishment of buildings?
- The building regulations help ensure that new buildings, conversions, renovations and extensions (domestic or commercial) are going to be safe, healthy and high-performing.
- BSI defines a standard as ‘something that is generally accepted’. British Standard (BS) publications are technical specifications or practices that can be used as guidance for the production of a product, carrying out a process or providing a service.
Can you explain some of the recent regulatory changes to the Building Regulations or British Standards?
- Updates to Part F and Part L in June 2022.
- Part F – Increased ventilation (to balance changes to Part L).
- Part L – Uplift in U-values, requirement for continuous insulation (no gaps).
- Part O – Overheating (limiting solar gains and ability to quickly remove excess heat).
- Part S – Infrastructure for charging electric vehicles.
- Part T – Toilets.
What are G-values?
- A measure of the amount of heat let into a building through its windows.
- Measured between 0 and 1 (0 is nothing, 1 is everything).
What are U-values?
U-values measure the amount of heat loss / gain through a building element.
U-value = 1 / the sum of all R-values (thermal resistance) of the individual layers making up a building element (a lower U-value means greater resistance).
What are R-values?
R-values measure thermal resistance (a higher R-value means greater resistance).
What are L-values?
L-values measure how airtight windows are (the lower the better).
What British Standards are you aware of that influence the ways in which buildings are constructed?
- BS 8102:22 Code of Practice for Protection of Below Ground Structures Against Water Ingress.
- BS 9999 (fire safety in the design, management and use of buildings).
- BS 8215 (installation of damp proof courses in masonry construction).
- BS 3921 (compressive strength of bricks).
Can you give some examples of different types of construction?
- Foundations – strip, raft, pad, pile.
- Floors – suspended timber, suspended concrete, block and beam, ground bearing concrete slab
- Walls – solid, cavity, framed.
- Roofs – flat (warm/cold/inverted), pitched (dual/mono pitch, hipped).
What are the different types of foundations commonly used?
- Strip foundations – low-rise residential buildings.
- Pad foundations – heavy concentrated loads (columns sit on top of pad).
- Raft foundations – poor soils, used to spread load where individual column loads are heavy in poor soil conditions.
- Piled foundations – Low bearing capacity sub-soils – requirement to transmit load to low level in ground. Typically used for large or high-rise buildings.
What are the different types of piling and when would you use them?
Bored Piles (Replacement Piles)
- A hole is bored in the ground using a piling rig with flight auger. The void is then filled with reinforcement if required and concrete (either pre-cast or in-situ).
- Used in cohesive soils such as clay and where vibration and noise are to be kept to a minimum.
Precast Piles (Displacement Piles)
- Precast concrete piles are driven into the ground using a piling rig with a drop hammer, displacing the subsoil.
- Used in non-cohesive (sandy) soils and where vibration and noise is not an issue.
Secant Piles
- A permanent structural wall is formed of interlocking bored piles.
- Primarily female piles are bored and cast with spaces in between for the boring and casting of secondary male piles.
Sheet Piling
- Sheet piling can be used as temporary support in excavations but also to form permanent retaining walls.
- The sheet piles have interlocking joints and are available in a range of sizes and strengths, up to a typical maximum length of 18m.
How would you establish the load bearing walls within a property?
- Check to see if wall is solid masonry or lightweight partitioning.
- Check direction of joists (if perpendicular to walls, likely to be load beading).
- Check to see if there is contact between the tops of walls and ceiling joists.
- Central / spine walls are likely to be load bearing.
- Check positioning of walls in relation to upper floor walls and roof timbers e.g. struts that may be supported by load bearing walls.
What are the potential implications of using two different (abutting) floor constructions?
- Reduced ventilation to suspended timber floors if concrete floor is added.
- Increased likelihood of condensation within sub floor and subsequent rotting of timbers.
- Ducting should be provided within concrete floor to maintain cross ventilation.
- Using a combination of suspended concrete and timber floors would maintain provision for cross ventilation.
Can you explain the build-up to the external render system specified for 86 Victoria Street?
3no. coat system (NHL 3.5)
- Scratch coat (applied up to 10mm, flattened and keyed/scratched)
- Float coat (rubbed up with a normal float and finished with a devil float to provide a key for the top coat)
- Top / finishing coat
Was there any requirement for upgrading of the thermal performance of the external walls when re-rendering?
- Alterations were made internally to external walls to meet a minimum U-value of 0.26.
- Required when over 25% of the surface area of the external building envelope is renovated – classed as a major renovation.
What are the benefits of a silicone render and when would use specify its use?
- Highly durable.
- Low maintenance.
- Provides a level of breathability.
What are the different types of lime and when would you use them?
- Hydraulic lime – for use in exposed locations – sets fast, durable, less flexible and permeable than non-hydraulic lime.
- Non-hydraulic lime – for use in less exposed locations – sets slowly, less durable and more flexible and permeable than hydraulic lime.
What are the different grades of natural hydraulic lime (NHL)?
- NHL 2 – Internal plastering or pointing up soft masonry.
- NHL 3.5 – General bedding and pointing mortars.
- NHL 5 – Limecrete floors and exposed areas.
What is a castellated beam and when would you use one?
- A castellated beam is a beam that has a regular and repeating pattern of hexagonal or circular holes.
- The provide a high strength to weight ratio – deeper beams using less steel.
