*General Defects Flashcards
Name 10 defects you would commonly find in a Georgian building.
- Leaning chimneys
- Overloading of roof due to change of materials (e.g. concrete tiles)
- Removal of chimney breasts but not the stack
- Blocked internal gutters
- Brick walls prone to distortion due to lack of restraint at each floor level
- Damp penetration through solid walls
- Rotting timber joists that are built into external wall
- Dry rot caused by poor cross-ventilation in narrow, long terraces
- Shallow foundations causing dropping of central spine wall
- Damp basements
Name 10 defects you would commonly find in a Victorian building.
- Leaning chimneys
- Overloading of roof due to change of materials (e.g. concrete tiles)
- Removal of chimney breasts but not the stack
- Damp penetration through solid walls
- Rotting timber joists that are built into external wall
- Wall tie failure (if a cavity wall, particularly in black ash mortar)
- Differential settlement of bay windows (little to no foundations)
- Rising damp caused by lack, failure or bridging of DPC
- Blocked air vents to ground floors, causing dry rot
- Lead water pipes
What defects would you expect to see in properties built between 1945-1970?
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Name 10 defects you would commonly find in a 1960s high-rise office block.
- Flat roof problems
- Parapet walls (loose copings)
- Poor workmanship (inadequate re-bar cover)
- Concrete defects - carbonation/chloride attack
- Deleterious material - asbestos/HAC/brick slips
- Cold bridges
- Overloading of floors (filing cabinets)
- Poor access and egress - narrow staircases, change in levels
- Brittle metal windows
- Corrosion of steel fixings
A 1960s building has misaligned concrete panels - what are the possible causes and what investigates would you undertake?
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Name some common defects in a 1970s building.
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In a steel frame brick wall 1950s building, what particular defects would you be looking for?
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What defects would you commonly find in a CLASP building?
- Penetrating damp through failed joints
- Poor gaskets around windows
- Pitched fibre drainage deformed, collapsed or become blocked
- Cold bridges
- Excessive solar gain to some elevations
- Poor U-values of the building fabric
- Asbestos - boarding around steel members/ceiling tiles/pipe lagging/floor coverings etc
- Rotting of timber floors and roofs in earlier Marks
What is cold bridging?
- Cold bridging occurs in localised spots where the nature of the construction allows heat to escape through the structure at a higher rate than normal
- This creates situations where there may be quite low internal surface temperatures which can encourage patches of local condensation
Where would you expect to find cold bridging?
- Concrete lintels crossing cavity walls
- Uninsulated box-section lintels
- Jambs and sills with returned blockwork inner leaf
- Floor slabs lacking insulated upstands
What is radon and why is it a problem?
- Natural radioactive gas that cannot be seen, smelt, heard or felt
- Emanates from minute amounts of uranium that occur naturally in all rocks and soils
- Most radon disperses harmlessly into the air outside but some will collect in spaces under or within buildings
- Exposure to high levels of radon can increase the risk of developing lung cancer
In which areas of the UK are you most likely to come across radon?
Some parts of the country (e.g. the West Country, Derbyshire and Northamptonshire) have higher levels than elsewhere
Other than radon, what other ground gases are problematic and why?
- Methane - explosive in air at concentrations between 5-15%, generated by the anaerobic (absence of oxygen) degradation of organic material
- Carbon dioxide - dlassed as highly toxic - can result in headaches and shortness of breath
Name some legislation that detail requirements when considering ground gases.
- Town and Country Planning Act 1990 - potential for contamination and risk from landfill and ground gases must be considered during development
- Environmental Protection Act 1990 - where potential for significant harm exists to a development (either existing or proposed), the local authority can enforce appropriate remediation or mitigation
- Building Regulations Approved Document C - where there is a potential risk, further investigation is required to determine whether gas measures are required and what level of protection is necessary
How would you find out whether radon gas was a problem in a particular area?
- Desk-based study of the history and geology of the area and any additional information such as mining or landfill activities
- Public Health England (formerly the Health Protection Agency) and the British Geological Survey publishes maps of radon affected areas across and sets threshold levels for both commercial and residential properties
- Maps can also be found in BRE Report BR 211 (Radon)
What steps would you need to take if your client wanted to build in an area where radon gas was present?
Passive (basic protection):
- Usually achieved by increasing the airtightness of the DPM and extending it across the external leaf of brickwork
- Can also improve ventilation under suspended timber and concrete floors by installing airbricks
Active:
- Used where risks are higher
- Sump pumps connected to a fan in order to extract
- May be required if protective membrane is damaged
Alarm Systems:
- Designed to trigger when gas concentration reach a certain level
What is Japanese Knotweed and when was it introduced?
- A hardy bamboo-like plant that grows quickly and strongly
- Introduced to the UK in the mid-19th Century
What legislative controls exist for Japanese Knotweed?
- Banned in the Wildlife and Countryside Act 1981, making it an offence to plant or cause the growth of Japanese Knotweed
- The Environmental Protection Act 1990 also contains a number of legal provisions, designating contaminated soil as controlled waste, meaning only properly licensed organisations can remove it
What problems are associated with Japanese Knotweed?
- Japanese Knotweed is extremely invasive and can cause serious damage to:
- Drains and buried services - can exploit cracks and gaps in pipework
- Patios, paths and drives - can grow between joints
- Boundary and retaining walls - can undermine walls with shallow foundations
- Outbuildings - can overwhelm lightweight structures (sheds, garages etc.)
- There are claims that damage to building foundations can also occur, however this is rare
- The plant can remain dormant, so eradication may be difficult to guarantee
How would you identify Japanese Knotweed?
RICS Information Paper ‘Japanese Knotweed’ - Appendix C contains an identification chart throughout the seasons, namely:
- Hollow stems within distinct raised nodes (like bamboo) which develop purple speckles
- Can reach heights up to 3-4m in its growing season (summer) and grow in dense clumps (aka ‘stands’)
- Leaves are lush green and flat heart/shield shaped, approx. 70-140mm long and 50-120mm wide
- Flowers are small, creamy white spikes of length approx. 60-150mm