Dealing with damp
How much does it cost to repair damp?
By Liz Ransome-Croker
Article 5 of 7
Find out the typical cost of different types of damp treatment so you know how much you should be paying to stop damp in its tracks.
Repairing a damp problem can be expensive. Here we look at typical costs and give you expert advice to make sure you don't end up spending more than you need to.
Damp proofing costs can run into the thousands of pounds and be very disruptive, as the most extreme works significantly affect your home's structure. Make sure you're prepared for the potential costs – and don't overpay for work – by reading our guide below.
Costs for dealing with damp
We've worked with the Royal Institution of Chartered Surveyors, which publishes average building work and repair costs, to bring you the average cost for a range of different damp treatments, from repairing a damp-proof course with silicone to laying an entirely new damp-proof membrane.
To give a more realistic idea of what treatments might cost you, we've provided prices for terraced, semi-detached and detached houses, as well as the costs for treating just one wall or one area.
Which? members can log in now to see all the prices in the tables below, as well as findings from our damp investigation, which revealed bad practice from a number of damp specialist companies.
If you're not a Which? member, you can gain instant access to all this information, and our investigation findings, by joining Which?.
About these costs
To arrive at the average prices above, RICS uses cost data from its Building Cost Information Service (BCIS) database, where costs are collated from a variety of sources and analysed.
Material costs are based on the best trade prices from a range of suppliers across the UK, which are then benchmarked to reveal the best national average. Labour rates are based on the current Building and Allied Trades Joint Industrial Council wage agreement. Prices correct September 2019.
Damp jargon buster
We've explained some of the common damp treatment terms below, but it's also worth visiting our pages on condensation, rising damp and penetrating damp for more details.
|Damp jargon buster|
|Word or phrase||Explanation|
|Damp-proof course (DPC)||A horizontal strip, often made from plastic or bitumen felts, built into the wall at the height of at least 15cm above ground level.|
|Damp-proof membrane (DPM)||A sheet of material, impervious to water, laid under the concrete floor. This should be connected with the damp-proof course so that the house is effectively sealed and protected from ground water.|
|Silicone damp-proof barrier||Instead of inserting a new damp-proof course, silicone is sometimes injected into a wall to create a barrier.|
|Cavity tray||Used in a cavity wall to act as a way to drain any water away from the inner wall to the outside through 'weep' holes (holes in a part of the outer wall). These are usually used around places where something 'interrupts' the wall, such as windows. These come in many different forms, depending on where they are in the wall, and made of many different materials.|
|Tanking||Covering an entire damp area, such as a whole wall or floor, in damp-proof material (either a membrane or liquid), to effectively 'seal' the area and protect it from moisture.|
Don't pay for unnecessary damp treatment
Damp can be a complex issue, and there can sometimes be more than one solution. The most expensive cure might not be the only option, or you may be able to do something yourself, for free.
For example, condensation damp is reasonably easy to sort out and can often be dealt with by simply opening windows more often, stopping drying clothes indoors, turning your heating on more, fitting new vents or installing new bathroom and kitchen extractor fans. And with penetrating damp, something as simple as clearing your gutters can also help.
We've heard from many Which? members who have tackled damp problems themselves, particularly condensation and some types of penetrating damp.
One said: 'I cleared the blocked gutter myself. It was a ten minute job.' Another said: 'It was a simple issue of a tile that had come loose and I could fix that myself.'
Rising damp, which can be the most expensive type of damp to fix, is fortunately one of the least common kinds of damp.
Without letting your damp problem become too serious (damp can wreak havoc on building structures), it's worth taking a little time to monitor it so you can work out the cause might be. You could use this time to try out a few cheap or free treatments before you call a specialist in.
Read our condensation, rising damp and penetrating damp pages - the more you know the better armed you'll be if you do need to call in the professionals.
Get professional damp-proofing help if needed
If you do decide to call in a professional, get quotes from at least three companies (some do charge for a damp report, but you get this back if you use the company) and seek advice from an independent damp specialist if there are inconsistencies in the work you've been recommended.
That way, you'll find out whether or not the treatment is absolutely necessary, and will be able to weed out any firms that try to make you pay over the odds.
In our undercover damp-proofing investigation (see below), we found that households could be spending hundreds of pounds on unnecessary damp-proofing treatment.
In a snapshot assessment in 2012, Which? invited 11 damp-proofing companies to two houses with a total of three potential damp problems. These visits were then analysed by three damp-proofing experts, who found that in two thirds of cases the companies recommended unnecessary or inappropriate treatment, or missed the problem completely.
Five of the 11 damp companies that visited the first property recommended completely unnecessary treatment according to the experts – some costing as much as £1,440 – when really they should have suggested asking a plumber to fix a leak.
In the second property, only two of the 11 companies recommended a suitable solution for the penetrating damp problem in the hallway. In this property five companies also failed to notice the likely damp penetration/rising damp problem at the front of the house. Of the six who did identify it, only four recommended a suitable treatment.
Which? members can log in now to see the full findings from our investigation as well as all the prices in the tables below. If you're not a Which? member, you can gain instant access to all this information and thousands of reviews by joining Which? today.