Building Pathology Flashcards
Typical defects of 1960’s high-rise office block?
- Structural issues (beams, columns and foundations).
- Water damage
- Electrical systems (outdated/unsafe)
- Plumbing problems
- HVAC systems
- Asbestos
- Lead paint
- Roofing issues
- Windows & Doors
- Foundation settlement
Most common type of wood boring insect
Death watch
Furniture beetle
Weevil
Longhorn
Describe wet rot conditions and symptoms
- Moisture content circa 50%
- damp musty smell
- Timber soft and spongy
- Discolouration
- stains to affected region
- mycelium may appear
Dry rot conditions and symptoms
- Moisture content ideal = 22%
- Can occur between 20-30%
- Soft and spongy timber
Mycelium can have yellow tinge - Mycelium turns grey when older
- Damp musty smell
- Fruiting bodies
- Damages structural strength and spreads via spores (even through walls)
Stages of dry rot?
- Spores
- Hyphae - fine white strands
- Mycelium - white appearance
- Fruiting bodies
Brown rot =?
White rot =?
Brown = dry
White = wet
Issues of dry rot?
- Can be hidden within the timber
- Damages timber including strength
- Can spread between timbers
- Low level of moisture required.
Where would you expect to find rising damp?
- Internal side of external wall
- Tide mark of circa 1 metre
How can you identify rising damp?
- Tidemarks
- Paint/skirting board damage
- salts in plaster
- damp and musty smell
- Checking it’s not another issue i.e. misdiagnosis.
How does rising damp occur
- Capillary action
When were DPC’s mandated
- 1875
Health Risks of mould
- Coughing
- Infection
- Asthma
- Allergic reaction
- Carcinogenic
- Depression
Common causes of spalled bricks?
- Moisture
- Rain
- Snow
- Soil
- Freezing
- Heat
Issue with organic growth on walls
- trap water
- frost damage
Subsidence v settlement
Subsidence - Supporting soil moves away from support allowing structure to move
Settlement - structure moves soil due to application of load
Explain sequence to underpin strip foundation?
- Mass concrete underpinning: excavate underneath, reach stable stratum, fill with concrete
- Cantilever needle beam
- Pier and beam
- Mini pad
What is high alumina cement and what are the issues
- Cement widely used in structural concrete
- Susceptible to crystalline rearrangement when exposed to water for long periods of time
- Leads to building collapse - e.g. swimming pool 1975?
What is meant by concrete cancer
Name for steel reinforcement expanding due to rust and displaces surrounding concrete.
Explain carbonation OF concrete
Chemical reaction which produces carbonates. This changes ph of concrete and if oxygen/water available leads to corrosion of steel.
Design regulations requires high strength - less porous concrete to protect this from occurring.
How does sulphate attack affect concrete?
Reaction of sulphate ions with calcium hydroxide and calcium aluminate hydrate to form gypsum and ettringite.
- Leads to expansion, cracking, strength loss and disintegration
What is ASR?
Alkali silica reaction i.e. concrete cancer
Defects of calcium silicate bricks
- More affected by shrinkage
- Less fire resistant
- Reduced water resitance
What is cold bridging?
An area in a building where a gap occurs in the building’s insulation. These areas will be prone to condensation.
Why do buildings crack?
Subsidence
Thermal movement
settlement
Heave - soil movement upwards
Loading
weather/weathering
Tree Roots
Sulphate attack
wall tie corrosion
Regent street disease
