Whether you are purchasing a property, carrying out alteration work or happily living in your house, the discovery of dry rot can have a major impact on the building and your finances. Dry rot is not as common as most people believe but it still exists.
Dry rot is a fungus which often causes extensive damage. It is a brown rot which occurs mainly on softwood in contact with dampness and wet brickwork. It is sensitive to high temperatures and dry conditions and rarely found on exposed timbers or in locations where there are varying conditions such as well vented sub floors. The signs to look out for are timbers that are brown in colour with dry cuboidal features easily broken or crumbled in your hands. There may be areas of fine orange or brown dust and fine greyish strands like cobwebs which allow the dry rot to spread. These will be accompanied by white mycelium which is a silky cotton like material, grey to pure white in colour that dry rot produces when it spreads to nearby timber. One of the other distinguishing features is the mushroom like fruiting bodies which release spores into the atmosphere to begin a new cycle. One of the most distinguishing features of dry rot is that it is accompanied by a damp musty smell. Dry rot spores in themselves are not harmful to health and are present in the atmosphere in most buildings but develop into dry rot when the conditions are right. Another key characteristic of dry rot is that it can readily grow over and through porous masonry provided there is a nutritional source such as wood from which it can spread. This ability allows the spread of the fungus from one area to another.
To treat dry rot, locate and eliminate any source of moisture, dry out the structure, cut away and remove effected timber. The fungus in walls can be treated using preservatives in cases where drying will be delayed. All replacement timber should be preserved treated timbers and treat all remaining sound timber which is at risk with a preservative. Also where possible introduce support measures such as ventilation or barriers such as damp-proof membranes. It is important to note that the cost of repair resulting from dry rot is generally not covered by household insurance policies as these specifically exclude dry rot cover however it has been caused as insurers believe that dry rot is the result of an ongoing issue and lack of maintenance. There are exceptions if it can be associated with a specific incident covered by your insurance policy where insurers may be sympathetic and make an ex-gratia payment or contribution towards the repairs. This is the exception rather than the rule. Finally if you are purchasing a house where work has been carried out to remove dry rot then you should enquire whether there is an insurance backed guarantee for the work and if it is transferable to you as the new owner.