Pests & damp

Pests & damp explained

This hub covers rodent control, insect infestations and wasp nests, alongside damp surveys, rising and penetrating damp, condensation, mould and timber treatment. Pests and damp sit together because they often share a cause. A gap in brickwork, a leaking waste pipe or a cold, unventilated corner gives mice a way in and gives moisture somewhere to settle. Put the building fault right and both problems usually become easier to control.

You can do a fair amount yourself. Block small gaps, keep food sealed, clear gutters and run extractor fans while cooking and washing. Treatments using professional products, structural damp and timber decay all need a qualified contractor. Condensation is often mistaken for rising damp, which is less common than many people assume, so have the cause assessed properly before paying for a damp proof course.

Older British housing changes the picture. Solid brick walls, built without a cavity, handle moisture differently from modern construction, and many have no original damp proof course. Sealed windows, blocked air bricks and internal insulation can cut the ventilation these homes relied on. A Victorian terrace, a 1930s semi and a new flat can show the same damp patch for three different reasons, so the survey matters more than the product.

What moves the price

Pest species and infestation size

A single wasp nest is typically £60 to £150, while bed bugs or an established rat population in a roof void run £400 to £1,200.

Number of visits in the treatment

Rodent and insect work is usually sold as a course, so expect £100 to £180 for one call and £180 to £400 for two or three visits.

Whether the damp survey is independent

A contractor's free damp survey costs nothing but carries a sales interest, while an independent report from a qualified surveyor is usually £200 to £500.

Metres of wall needing replastering

Chemical damp proof injection runs roughly £70 to £130 per metre of wall, and the replastering behind it often costs more than the injection itself.

Ventilation work and making good

Fitting an extractor fan is about £180 to £400 and a positive input ventilation unit £500 to £1,100, before any redecoration.

Figures are indicative typical ranges for the UK, not quotes. Always get written quotes before work starts.

Before you enquire

• Photograph the damp patch or droppings, and note whether it appears after rain or on cold mornings.
• Clear access to skirtings, external walls, the loft hatch and the space under sinks.
• Have dates of recent leaks, insulation work or window replacements ready for the surveyor.
• If you rent, report the problem to your landlord or agent in writing and keep a copy.

Common questions