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Dealing With Damp, Rot And Pests

By: Chris Hogan MSc - Updated: 8 Apr 2013 | comments*Discuss
Property Renovation Renovate Roof Walls

If you’re tackling the renovation of a particularly old house, it’s fairly likely that you will come across some sort of damp, pest or rot. The good news is that they are all treatable. The not so good news is that they will all cost money to put right, some more than others. So the key, if you’re buying a property to renovate, is to make sure you know what you’re dealing with before you invest.

Important Research

As we’ve said in other articles, a full structural survey is very important, particularly if you intend to renovate for a profit. A full structural survey is much more than a building society’s quick check and will cost more, but it’s money worth spending and will let you know what you’re in for.


Although the damage caused by damp can be serious, the cause of damp, unless the property has simply been built in the wrong place, is usually relatively obvious and straightforward to put right.

'Penetrating damp' describes damp that comes in through the walls and is usually caused by faults in guttering or fascias, which can be fixed pretty easily. If it’s very close to ground level, the damp proof course (DPC) may be damaged, or even non-existent in an older house. But before getting a new DPC put in, look around the outside of the property to see if earth or badly constructed building work has come up from ground level and is allowing moisture to get at the brickwork above the DPC.

Condensation is moisture in the air inside the house, which can’t get out and leads to mouldy patches on walls and ceilings. This can be fixed by improving the ventilation. With both condensation and penetrating damp, once the cause is isolated, a dehumidifier will help dry the affected areas out before fixing the damage and redecorating.

Living Pests

Pests can vary from the benign to the destructive. Rodents and birds can be dealt with by professional services and in many cases the local council will have a service that will help. Be aware that some animals, bats for example, can be protected species and you may not be able to exterminate them. Most councils will also tackle any bee and wasp nests, but other insects infestations will need specialist treatments such as fumigation. In extreme circumstances, this may require you to leave the home while the chemicals do their work.

Currently, the most damaging insects common in the UK are death-watch beetle and woodworm, both of which attack the wooden structures in a home. After eradication, much of the affected wood will have to be replaced, so it depends on where the infestation has taken hold as to how disruptive and expensive this might be. Other insect such as silverfish and woodlice are not such a big problem in themselves but may indicate a damp problem.

Wet and Dry Rot

Rot is divided into two categories, wet and dry, and the most benign is wet rot. This describes wood that has been damaged by damp, and can be fixed by solving the damp problem, then drying out and repairing the wood. Depending on the extent of the damage, this might be just sanding and repainting, but it could mean cutting out damaged wood and replacing it.

Dry rot is another matter altogether, referring to damage caused by a fungal growth, which lives off the cellulose in the timbers. Confusingly, the fungus does actually need damp to thrive in the first place. The term ‘dry’ refers to the fact that it can take hold in wood that has been dried before being used in construction, as opposed to green or live wood.

Dealing with Dry Rot

Removing the structural cellulose from the cells of the wood leaves a skeleton behind, and if the fungus spreads unchecked this will eventually lead to collapse. Dry rot favours dark places and this can make it difficult to find, often spreading behind plasterwork or in roof spaces or other voids. Treatment requires the resolving of the damp problem that allowed the fungus to take hold in the first place and completely drying out the area. After that, the damage can be assessed and wood and surrounding material made good.

Guaranteed Results

Whichever problem you are unfortunate enough to encounter, make sure you research and investigate specialist firms before engaging them. You may not be able to get a personal recommendation, but make sure firms are members of a regulatory body and if possible, ensure that the guarantees they offer are backed by that body, or an insurance company, so that you’re covered if the firm stops trading for whatever reasons. If they don’t offer a guarantee, don’t use them!

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