Building Pathology - Flash Cards - L1
What are some Victorian building key features
Built within 1837 - 1901
Bay windows
Stained glass windows
Porches to the front of the building
High ceilings, usually ornate if original.
Decorated black and white gable and bargeboards
Feature fire places, chimneys in most rooms.
What are some Victorian Building defects
Roof – Sulphate Attack to chimneys.
Roof – Chimney support / breast removal.
Roof – Slipped or cracked slates. Lead or copper tingle put in place to hold slipped slates. Nail sickness.
Roof – Overloading of the structure, adding concrete tiles. This causes sagging in the timbers.
Roof – Rainwater good failure, corroded or blocked.
Roof – Flashing defects.
Walls – No DPC 1875 Public Health Act.
Walls - Snapped headers, poor restraint wall ties. This causes bulging walls when they fail.
Walls – Timber lintels and decay.
Walls – Removal of internal structural partitions.
Foundations – Shallow foundations.
Deleterious Materials – Lead paint.
Deleterious Materials - Asbestos
Deleterious Materials – Animal hair (anthrax).
What are some Georgian building key features
Built between 1775-1849, 18th century
Symmetrical facade
Sash windows
External columns and other features of roman architecture
Use of render externally, with a painted finish.
What are some Georgian Building defects
Walls – No DPC
Walls – Snapped headers, poor restraint wall ties. This causes bulging walls when they fail.
Walls – Stone defects and sulphur attack.
Walls – Damp penetration through thin walls.
Walls – Timber lintels and decay.
Walls – Cracking stucco render / water ingress.
Foundations – Shallow foundations.
Finishes – Lime plasters replaced with modern gypsum or cement which is not breathable.
Deleterious Materials – Lead paint.
Deleterious Materials - Asbestos
Deleterious Materials – Animal hair (anthrax).
What are some common flat roof defects
Standing water – Caused by blocked drains, or the roof not having the correct slope for affective drainage.
Blistering – Caused by moisture being trapped under the surface. Loss of adhesion allows any moisture to evaporate expanding a blister under the surface.
Crazing – Can be caused by repeated thermal movement.
Cracking - Can be caused by repeated thermal movement or incorrect protection from being walked on.
Poor flashing details – Incorrect or damaged flashing details can allow water ingress under the flat roof membrane.
Incorrect upstands – Upstands not installed to the correct minimum height of 150mm.
How is standing water remedied on a flat roof?
Check existing drainage, clear out if blocked.
Replace the membrane to reduce the likelihood of leaks (ponding water speeds up the wear and shortens lifespan)
Fill low spots or add in more drain lines if possible.
Install flat roofing cricket, V shaped hump to push water away.
How is blistering / cracking remedied on a flat roof?
Depending on the severity of the blister, it can sometimes be better to just leave it alone.
If it is showing signs of cracking or it is near a seam the membrane will need to be cut away until you reach an area where the membrane is still adhered. A new membrane will need to be patched over the area that the defective area was removed.
What are some key considerations when repairing lead flashings to a flat roof?
Lead flashings should be at least a code 4.
Lead flashings should not exceed 1.5m in length with laps of no less than 100mm.
Flashing should be tucked into a mortar joint 25mm deep and at least 75mm above the tiling level and lead wedged into place.
Flat roofs should have a minimum 150mm upstand with flashing installed above.
Name some common flat roofing systems?
EPDM
GRP
Traditional BUR - pour and roll
MBR modified bitumen roofing
Liquid coating system
Mastic Asphalt
What are some key items to consider when replacing flat roof coverings?
The potential to an overlay option
The potential to convert a cold roof to warm roof or inverted.
Is the existing waterproofing attached adequately to the deck.
Whether the removal of the waterproofing would damage the deck.
Check the ceiling void for insulation present / deck.
Check for ventilation methods.
Condition of the deck.
Name some pitched roof defects
Slipped or broken slates or tiles.
Broken or slipped ridge tiles.
Valleys blocked or cracked (concrete or lead) causing leaks.
Mortar missing from verges allowing water into the roof space.
Poor flashing detail around chimneys.
Torn or missing roof flet.
Damage to timber rafters – water staining or split timber.
Damaged rainwater goods.
What are the three types of damp
Rising Damp - The upward movement of water through a porous material due to capillary action. BRE Digest 245 - Rising damp in walls.
Penetrating damp - Damp caused by moisture passing through a building fabric.
Condensation - When moist air contacts a surfaces with a lower temperature, below the dew point creating moisture droplets.
How would you identify rising damp?
Locations: Ground floor level
Identification: Typically rises above 1/1.5m from ground level (more severe cases it can be higher), tide mark is shown with (efflorescence) salt deposits where water evaporates, peeling / detachment of wall finishes, and a musty smell / decayed timber.
The height of the moisture rising depends on the pore structure of the bricks & mortar and the rate of evaporation (heating in property). Masonry containing a high proportion of fine pores will allow moisture to ruse higher than ones with less pours.
What are the causes and testing methods for rising damp?
Causes: No DPC (requirement of 1875 Public Health Act), damaged DPC (original slates could be damaged), and bridged DPC (steps, landscaping, render).
Testing: Damp meter testing, although can be misleading due to hydroscopic salts (calibrated for timber). Salt tests, identifies nitrates and chlorides.
How would you rectify rising damp?
Refer to BRE digest 245 on rising damp in walls.
Un-bridge DPC / repair DPC.
Remove damaged plaster / render at least 300mm above height level of damp.
Replaced with breathable / waterproof alternatives,
Retrofit DPC physical or chemical using specialist.
How would you identify penetrating damp?
Locations: Above ground.
Identification: Localised damp, staining, tracking of moisture.
What are the causes and testing methods for penetrating damp?
Causes: Failed rainwater goods, failed roof coverings, leaking services, poorly sealed penetrations.
Testing: Damp meter (depending on material), dye testing, moisture mapping.
How would you identify condensation?
Locations: Inside a building.
Identification: Water droplets forming on surfaces, Mould / damp occurring.
Interstitial, where condensation occurs in voids / cavities. Cold bridge, building element of inferior properties to surrounding surfaces providing a passage for heat to travel / exchange. Warm front, occurs externally (A/C buildings).
What are the causes and testing methods for condensation?
Causes: Increased humidity (moisture in the air).
Testing: Humidity monitoring.
How would you rectify condensation issues?
Natural / mechanical ventilation, increased insulation and heating.
What is dry rot?
Living growing fungus that feeds on timbers and actively seek out new sources, especially when humidity levels are right.
How is dry rot identified on timber?
Effect on the wood - Becomes light in weight, crumbles under the fingers and has a dull brown colour. It shrinks and splits in to cubic pieces.
Strands - Strands are a grey / white colour, 2 - 8 mm thick, become brittle when dried.
Mycelium - In damp, dark places, soft white cushions or silky growths. In drier places, thick silver-grey sheets or skins usually showing patches of lemon yellow and tinges of lilac.
Fruiting body & spores - Fleshy and soft fruiting bodies, but tough shaped like pancakes or brackets. Spore bearing surface rusty red with shallow pores or ridges . Spored settle as a rust coloured dust.
What humidity level does dry rot occur?
20 - 40 percent
What materials can dry rot affect?
Timber, plaster, masonry and concrete.
What information would you refer to for information / treatment on dry rot?
BRE Digest 299 - Dry rot: recognition & control
How would you recommend that dry rot is treated?
Primary Control:
Locate and eliminate source of moisture.
Promote rapid drying (heating & ventilation).
Secondary Control:
Determine extent of damage.
Remove timber 300-450mm beyond affected areas, and dispose of.
Remove plaster 1000mm beyond affected areas.
Treat fungus in masonry with a liquid application.
Treat retrained timbers with a liquid application.
Replacement timbers are to be pre treated and hung on joist hangers.
What is wet rot?
Wet rot is a type of fungal decay that affects untreated wood that is exposed to water or high moisture levels
How is wet rot identified on timber?
Effect on wood - Timber will have a brittle texture with small linear or cuboidal cracking . Usually there will be a thin skin of wood covering the affected area. The timber will show signs of weight loss.
Strands - Web like strands spanning across wood only, thinner than dry rot and flexible when dry, creamy white in colour.
Mycelium - Wet rot shows more of a skin or coating and is bright white.
Fruiting bodies - Small mushroom like fungi that are off white, with a musty smell.
What humidity level does wet rot occur?
50-60%
What materials does wet rot affect?
Timber only
What information would you refer to for the treatment of wet rot?
BRE 345 - Wet rots - recognition & control
How would you recommend that wet rot is treated?
Primary control:
Locate and eliminate source of moisture.
Promote rapid drying (heating & ventilation).
Secondary control:
Determine extent of damage.
Remove timber 500mm beyond affected areas.
Treat retained timbers, fungicidal wash.
Replacement timber to be pre-treated.
What are common types of insect decay?
Death watch beetle
Common furniture beetle
Both are types of woodworm.
How would you differentiate death watch beetle to common furniture beetle?
Death watch - Hardwoods, oak / elm, occasionally softwoods, timber suffering from fungal decay, larger, grey / brown, 5-7mm in length, active March - June.
Common furniture - Structural timbers both hard & soft, prefer damp timber (roof voids or ground floors), 2.5mm in length, spring to summer.
How would you treat insect decay?
Employ a specialist contractor, received insecticide treatment, and replacement of timbers depending on the severity / timbers job.
Name 3 common types of concrete defect?
Carbonation, chloride attack, sulphate attack.
