Dampness and Condensation Flashcards
What can cause dampness?
Poor design
Poor construction
Severe weather
Owner negligence
Poor materials
What are the 3 types of damp?
Penetrating
Rising
Condensation
What physical defects of a building can lead to damp? (Big list)
Blocked gulleys causing splashing rainwater
Rusted downpipes or broken joints
Overflowing hopper heads
Copings without drips or not needed on DPC’s
Inadequate chimney / parapet flashing
Redundant chimneys not capped or caps damaged
Cracked render
Defective pointing
Poor quality bricks
Movement cracks
Badly fitted windows
Cills without drips
Poor threshold design
Dropped arches
Warning pipes running
How can renders in walls cause damp?
Shrinking and cracking allows water penetration
What are the key features of penetrating damp?
Often in localised areas
Sharp change from wet to dry
Efflorescence (sulphates, carbonates)
Lack of mould growth
High moisture content in timber
What happens in stage 2 for diagnosing penetrating damp?
Deep wall probes indicate high readings in the centre of wall
Salt analysis shows zero nitrates and chlorides
Measure wall temp, air temp and humidity to eliminate condensation
What are the key features of rising damp?
Limit usually 1-1.5m above ground level
Readings drop quickly at dampness peak
Stains and/or tidemarks on wall
High % of moisture in the timber skirtings
Damp areas get wetter in humid conditions
External inspection may indicate missing or bridged DPC
What happens in stage 2 of diagnosing rising damp?
Deep wall probes show high readings in wall centre
Salt analysis shows high levels of nitrates and chlorides
Establish surface temp, air temp and humidity to eliminate condensation
What are the key features of condensation?
Readings at full height of wall
Staining of skirting board
Moisture content of skirting normal
Mould growth
No sharp change from wet to dry
What happens in stage 2 of diagnosing condensation?
Low readings in centre of wall
Negative salt analysis
Measure surface temp, air temp and humidity to establish dew point. Surface temp below dew point = condensation
Consider use of protimeter
