Damp & Timber Treatment Calculators

Damp is one of the most common problems affecting UK properties, with an estimated 30–40% of homes experiencing some form of damp or moisture-related issue. The UK’s temperate maritime climate, with high rainfall, moderate temperatures and elevated humidity, creates ideal conditions for rising damp, penetrating damp, condensation and timber decay. Understanding which type of damp you are dealing with is critical before starting any treatment.

Rising damp occurs when groundwater is drawn up through masonry by capillary action, typically affecting walls up to about 1.2m above ground level. In older properties built before 1875 (when damp proof courses became standard), or where the original DPC has failed, rising damp can cause salt deposits, peeling plaster and damp staining. Treatment involves injecting a chemical DPC cream (usually silane/siloxane) into holes drilled at 120mm centres along the mortar course, followed by replastering with a salt-resistant specification. Our rising damp calculator works out drill hole spacing, DPC cream cartridges and replastering quantities to BS 6576 standards.

Condensation is the most frequent cause of dampness in UK homes, accounting for the majority of damp complaints. It occurs when warm, moist air meets a cold surface, causing water vapour to condense. Poorly ventilated bathrooms, kitchens and bedrooms are especially prone. The condensation risk calculator uses simplified dew point calculations to assess whether your wall surfaces are at risk, helping you determine whether improved ventilation, insulation or heating is needed. BS 5250 and Approved Document Part C provide the regulatory framework for controlling condensation in buildings.

Timber decay in UK properties takes two main forms: wet rot and dry rot. Dry rot (Serpula lacrymans) is the more serious, as the fungus can spread through masonry and across surfaces that are not even damp. Treatment requires cutting back all affected timber at least 1m beyond the last visible sign of infection, applying fungicide spray to remaining timber and masonry, and replacing removed timber. The dry rot calculator estimates fungicide, masonry irrigation and replacement timber quantities following PCA (Property Care Association) guidelines and BS 7913.

Woodworm (wood-boring beetle larvae) is another common timber problem, particularly in older UK properties. Common furniture beetle (Anobium punctatum) is the most widespread species, leaving 1–2mm exit holes in softwood timbers. Treatment involves spraying or brushing insecticidal fluid onto affected timber surfaces. Our woodworm treatment calculator helps you work out the litres of treatment fluid needed based on the area and severity of infestation.

Mould growth is a direct consequence of condensation and high humidity. Black mould (Aspergillus niger and Stachybotrys species) can pose health risks, particularly for people with respiratory conditions. Treatment involves applying fungicidal wash and steriliser to kill the mould, followed by anti-mould paint to prevent regrowth. The underlying cause (poor ventilation, cold surfaces or water ingress) must also be addressed. HSE guidance recommends professional assessment for mould covering more than 1m².

All damp and timber treatment work should be carried out by qualified specialists, ideally members of the Property Care Association (PCA) or Trust Mark registered. Many treatments come with insurance-backed guarantees of 20–30 years. Our calculators provide accurate material estimates to help you plan and budget for treatment, whether you are a property surveyor, damp specialist or homeowner.