Care & Repair
Damp, rot and beetle
The issue of Damp and Timber in Victorian buildings is a major concern. For too long the public have been conned by an industry that are intent on selling chemical treatment products that more often than not do nothing to resolve the real problems.
Surveyors now generally accept that as much as 95% of alleged ‘rising damp’ is misdiagnosed. Most damp at low level can be cured by common sensible building work. If injection is carried out it should be into the mortar course otherwise if there really is rising damp it would finger its way through the mortar and past the injected bricks.
Further, the use of a tanking render internally after injection simply serves to mask the damp and can actually exacerbate the problem over time by allowing moisture to become trapped and build up behind the render.
Injecting a DPC is unlikely to be necessary, unlikely to solve the problem and often a waste of time and money.
The Burkinshaw and Parrott book on Damp (published by RICS) encapsulates present day thinking and demonstrates that in the vast majority of cases damp can be cured by sorting out the way the building and materials function rather than using chemicals, etc.
A common cause of damp around chimneys is water running down the flue and soaking into the soot and debris behind the fireplace. Simply clearing out a fireplace recess of debris can do wonders in sorting out such damp problems.
Rot and beetle infestation
We would advise chemical treatment of insect infestation only if there is a serious active attack. If it is Death Watch Beetle surface treatment does not get them anyway.
With rot, we need to get away from the simplistic and incorrect use of ‘Dry Rot’ and ‘Wet Rot’. They should be Brown Rot and White Rots. Although very different fungal growths there are some common factors important for the home owner. Rots can only germinate and attack if there is wet timber present and then only above 25% WME. Dry timber will not rot even if the spores are on the surface. Without damp as well the spores will not germinate and the timber will be safe. The fungal growths do not transport moisture to “wet up” dry timber – they simply cannot do this. From the 1950s it has been known that it was unnecessary to cut out 1m beyond the sign of rot attack, but of course the industry has not bothered to make it widely known because it is not in their interest.
Most rot treatment chemicals are borne in water and therefore to chemically treat rot affected timbers (or irrigating walls) you are introducing water, the very thing the rot needs!
To successfully treat rot the source of water MUST be found and dealt with. The area affected allowed to dry, the area ventilated if appropriate, timbers protected by isolating membranes where in contact with walls, etc. Replacement timbers should be pre-treated. If any treatment is to be used it is sparingly and only to protect timbers temporarily whilst the brickwork and area dries out.
Cuboidal cracking in timber is normally a Brown Rot and might be Dry Rot but it is NOT a White Rot. Wet Rot is the wrong term for this – far too generic.
The problem with using the wrong term is as follows. If the damage is ‘Wet Rot’ it could actually be either a Brown or White Rot attack and these are very different rots, they actually destroy different parts of the timber (Brown Rot being far more effective and therefore destructive). ‘Dry Rot’ is a Brown Rot. Therefore if something is identified as a White Rot it CANNOT be Dry Rot (a Brown Rot). However, if you call something Wet Rot it could be either Brown or White Rot and therefore a misdiagnosis could occur.