Building Pathology Level 1 Flashcards
How do you identify Dry Rot?
Large Cuboidal Cracking (Brown Rot)
Cotton-wool-like if damp: White/grey in colour with purple yellow and lilac patches if dry
Fruiting body reddish brown centre white margins; flat plate or bracket shape
Red Spore Dust
Where would you find Dry Rot
Inside Buildings
What conditions are required for Dry Rot?
20-40% slightly damp
0-26 degrees C
Name a type of White Rot and how you may identify them?
Phillinus Contiguous
Timber becomes soft and fibrous - External Softwood
Light brown masses
Timber moisture content 22% +
Temperature 0-31 oC
What are the two categories of Rot?
White and Brown Rots
Name a type of wet rot and how you may identify it?
Coniphora Peteana (Cellar Fungus)
(mainly leaks, failed plumbing)
Brown Rot
Cuboidal Cracking - Small cubes
Dark Brown
Brown mycelium on wood and masonry (not usually in daylight areas).
Rarely found inside flat plate like greenish brown centre yellow margin, knobbly surface.
Timber MC - 45%-60% (Very Wet)
Temperature range -30 deg C - + 40 deg c
How would you identify House Longhorn Beetle?
Local to Surrey and Berkshire only - (warmest parts of uk)
Flightholes 6-9mm
10-25mm in length and grey and black in colour
Flight season July - September
Frass- fine dust cylindrical pellets
Initially softwood/sap wood then heartwood. Can infest and reinvest dry timber
Likes structural roof timbers
Female larger than the male
How would you identify Common Furniture Beetle?
Around 5mm in length
Flightholes 1-3mm approx 2mm
Reddish- Brown Colour
Frass - granular pellets individual pellets ellipsoidal shape. Gritty feel like sand
Softwood and hardwood, maybe sap wood
Structural timber/ joists etc
Smooth Exit holes (circular)
What is the life cycle of a common furniture beetle?
Female lays eggs in cracks, joints or cervices - Does not like smooth varnished or waxed wood
Grubs hatch, create grass filled tunnels. Tend to move along the grain. Grub/ Larvae remains for 2 years minimum but average for 3-4 years
Crysalils early spring of the year it is going to emerge and moves to outside of wood.
Beetle then eats its way out and leaves a flight hole
Cycle starts again
How would you identify a Death Watch Beetle?
Likes Mature Hardwoods
Adult Male 5mm-7mm female slightly larger
Chocolate brown with mottled markings
Thorax hooded over head
Eggs laid in cracks/ crevices of old wood/ flight holes
Larvae up to 8mm and hairy in appearance
Sap and heartwood of hardwoods especially oak
Average lifespan 4-5 years up to 10
Frass easily seen as bun shaped individual grains
How would you identify a Wood Boaring Weevils
Cylindrical body with short legs
2.5mm-4.5mm in length approx
More common in London area
Damp timber is essential - softwoods or plywoods.
Ragged exit holes
Red/Brown - Black Bodies
Very fine grass - very fine and gritty texture
What is settlement?
Settlement is the downward movement of the ground caused by a load consolidating the soil below it or causing displacement of the soil.
Movement related to the weight of the building itself
What is subsidence?
Subsidence is usually caused by the ground shrinking through a loss of moisture. This is more common after prolonged periods of dry weather. Areas where clay forms a significant proportion of the soil can be vulnerable, particularly where the clay is highly shrinkable as it then also has a tendency to expand when wet.
Movement related to an external factor
What is differential settlement?
Differential settlement is the uneven or unequal settling of a building’s foundation.
What external factors can cause Subsidence?
Absorption of moisture by trees and shrubs which can cause the water content of the ground to fall.
Collapsing drains, culverts, hidden mine shafts
Improperly compacted ground.
What is the BRE digest for identification of cracks?
BRE Digest 251 - Assessment of cracking in low rise buildings
What are the categories of crack widths in the relevent BRE document?
0 - Hairline cracks: Less than 0.1 mm in width. No repair action required.
1 - Fine cracks: Up to 1 mm in width. Generally restricted to internal wall finishes. Easily treated using normal decoration.
2 - Cracks easily filled: Up to 5 mm in width. Not necessarily visible externally, but doors and windows may require adjusting to prevent sticking. Can be masked by suitable linings.
3 - Cracks that require opening up: Widths of 5-15 mm. Weather-tightness and service pipes may be affected. External brickwork may need repointing or, in some cases, to be replaced.
4 - Extensive damage: Widths of 15-25 mm. Windows and door frames become distorted, walls lean or bulge noticeably. Requires breaking-out and replacement of wall sections.
5 – Structural damage: Widths greater than 25 mm. Beams lose their bearing, walls require shoring, and the structure is generally unstable. May require major repair works.
What is Search Mode on a Damp Meter?
What is WME mode on a Damp Meter
What are the 2 ways to use a standard moisture meter?
What are the different types of Damp?
Rising
Penetrating
Condensation
Pipe Leaks etc?
What are the symptoms of rising damp?
Moisture gradient from the base of the wall
What is rising damp?
The process of water Evaporating up a wall as capillary action
What is condensation?
What are the symptoms of Condensation?
What defects could you find in a pre-1900 house or property?
Damp penetrating through 225mm walls
Failed or lack of Damp Proof Course
Settlement of windows or internal partitions walls
What defects might you find in a property aged between 1900 and 1939?
Poorly fitted sash windows
Steel frame corrosion - Regent Street Disease
Lead water mains
Wall tie failure
What defects might you find in a property between 1960s- 1980s?
Asphalt roof defects
Asbestos
Calcium silicate bricks
Cold bridging and condensation
Woodwool
RI concrete frames carbonation/ chloride attack
