A new technical publication on Salt Attack and Rising Damp has been published jointly by the Heritage Council of NSW, Heritage Victoria and SA Department for Environment and Heritage. Authored by APT Australia Chapter member David Young OAM, this publication provides excellent guidance on the diagnosis and treatment options for rising damp and associated salt attack in masonry buildings.
The publication can be downloaded in PDF format from the web, or hard copies purchased for $25 plus postage. Click here for details.
The guide explains how to diagnose and identify appropriate repair work for cases commonly seen in Australia.
A joint project between the heritage agencies in NSW, Victoria, South Australia and the City of Adelaide, Salt Attack and Rising Damp covers various climatic and geographical conditions found across NSW and south-eastern Australia, from coastal areas to arid regions. According to publication author David Young OAM, salt attack and rising damp are separate but interrelated processes. Both issues must be understood to minimise damage and to take corrective action. “While the term rising damp has been commonly used to cover both aspects, it tends to overlook the role of salt. This is an issue that will become increasingly important as our buildings get older and soils become more saline. While emphasis is given to buildings of heritage value, the principles apply to all older
buildings” , he said.
Dos and Don’ts of Damp
Do go out in the rain (the heavier the better) and check gutters and downpipes for blockages, leaks and overflows. Also check around the base of the building for water lying against walls.
Do check for the presence of a Damp Proof Course (DPC) – and ensure that it is continuous, and not ‘bridged’ by built up paving and garden beds.
Do remember that damp walls increase the risks of fungal rot and termite attack to floor timbers – always check beneath timber floors.
Do consider the possibility that your old building may have had previous treatments for rising damp, and that these may be obscuring the extent of the problem.
Do clean out existing air vents regularly – and monitor results before deciding to add new ones.
Do consider the possibility of salt attack decay into wall cavities – always inspect cavities for accumulation of debris (and corrosion of ties).
Do consider the implications of drying out the soils beneath your building. If it is founded on reactive (expansive) clay soils excessive drying could lead to structural cracking as a result
of differential settlement.
Do get independent advice – that way there should be no pressure to use a particular product or system. Check your adviser’s credentials.
Don’t use hard cement mortar to repoint failed lime mortar joints – that will just drive the damp further up the wall and may also damage the bricks.
Don’t even think about sealing walls with water repellent coatings.
Don’t mulch your walls. Move garden beds away from the base of walls and remove irrigation to prevent spray and pounding against walls.
Don’t dismiss the old tar and sand DPC – reduce the damp ‘stress’ on the walls, repair the DPC, use sacrificial mortars in the joints if necessary, and monitor results before considering an expensive new DPC.
Don’t undertake insertion of any form of DPC until all the basic housekeeping measures have been completed and their effectiveness assessed over a period of time (at least a year).
Don’t accept the cheapest quote for chemical damp coursing without checking the contractor’s references and the details of the proposed works, such as drill hole spacing and depth, and how the contractor will determine when sufficient fluid has been impregnated.
Don’t try to get away with using less chemicals and then locking in the inevitable damp with waterproof plasters – your client has read this too!