Building Pathology Flashcards

What does 'efflorescence' on brickwork indicate?

Answer: The presence of soluble salts being brought to the surface by moisture evaporation

Efflorescence is a white crystalline deposit that appears on brickwork when soluble salts within the brick or mortar are dissolved by water and deposited on the surface as the water evaporates.

What is 'thermal bridging' (cold bridging) in building construction?

Answer: An area of the building envelope where heat transfer is significantly higher than the surrounding materials

Thermal bridging occurs at junctions or points in the building fabric where insulation is reduced or absent, allowing heat to transfer more readily, which can lead to condensation and mould growth.

Which type of asbestos is considered most dangerous and was most commonly used in insulation materials?

Answer: Crocidolite (blue)

Crocidolite (blue asbestos) is considered the most hazardous form of asbestos due to its fine, sharp fibres. It was commonly used in pipe lagging, insulation boards, and spray coatings.

What is 'heave' in relation to building foundations?

Answer: Upward movement of the ground, often caused by clay soil expanding due to increased moisture

Heave is the upward movement of the ground beneath foundations, typically caused by clay soils swelling due to increased moisture (e.g., after tree removal), which can cause cracking and distortion.

What is the primary purpose of a 'cavity tray' in masonry wall construction?

Answer: To collect and redirect moisture that penetrates the outer leaf, directing it to weep holes

A cavity tray is a damp-proof membrane installed at vulnerable points (above windows, where roofs meet walls) to catch any moisture that penetrates the outer leaf and direct it outwards through weep holes.

What is the Building Research Establishment (BRE) Digest 251 primarily concerned with?

Answer: Assessment of damage in low-rise buildings, providing a classification system for crack widths

BRE Digest 251 provides a classification system for assessing damage in low-rise buildings based on crack widths, categorising damage from 0 (negligible) to 5 (very severe).