DAMPNESS IN WALLS
Water can enter a wall from above (falling damp) or from the ground (rising damp). Dampness can cause staining, smells and mould and can damage paint and plaster. When dampness is combined with salt, it can cause brick, stone and mortar to crumble.
Modern buildings are constructed with a ‘damp proof course’ – a waterproof barrier that sits above the ground and below floor timbers. Older buildings may not have a damp proof course, or that course may have been ‘bridged’ through changes to the building or landscaping. Learn more David Young, Salt Attack and Rising Damp: A guide to salt damp in historic and older buildings, 2008, Heritage Council of Victoria, heritage.vic.gov.au/resource-library Maintenance principles DO – Address the source of moisture and remove salts before repainting or replastering – Fix blocked or leaking gutters, failed flashing or roof joints, leaking hot-water or air-conditioning units, plumbing or drainage problems or build-up of garden beds. After fixing, monitor the area for improvements – Consider recent changes to the building or surrounds, such as new concrete floors, render, external paving or garden beds that can bridge the damp proof course or affect ventilation. Options could include introducing a separation from the affected wall (such as with a narrow trench) or replacing the floor/paving to a lower level – Improve ventilation, for example by clearing underfloor rubbish or blocked air vents
– Monitor signs of salt attack, such as white or brown deposits, crumbling or separation of the outer ‘skin’ of bricks or sandstone and deteriorating mortar. Seek specialist advice on the extent of rising damp and potential solutions, including: • Sacrificial treatments – using a deliberately weak mortar, plaster or render to prevent damage to brick or stone • Treatments to remove excessive salt, such as absorbent poultices or dry vacuuming • Installing a new damp-proof course • Improving ventilation, for example with an air drain
Things to avoid DO NOT
– Replace a ventilated floor with concrete slab or install external paving too close to the walls of a heritage buildings. This can cause problems with damp, by preventing evaporation or splashing water onto walls – Paint or render over unpainted/unrendered brick or stone. Water repellent coatings can prevent a masonry wall from breathing and cause further damage – Repoint with impermeable cement mortar, which can force water into and damage surrounding bricks – Build up garden beds or install sprinkler systems close to heritage buildings as these could cause problems with damp
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CITY OF CASEY: HERITAGE HANDBOOK
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