Have you discovered an issue with damp in your home? Whether it be a slight musty smell, an obvious patch of mould or a tide mark, it’s time to tackle the problem.
But how do you know if you need a full damp-proof course? What is it, and how much does damp proofing cost? In this guide, we’ve got everything you need to know regarding the cost of damp-proofing in the UK.
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Problems That Damp Can Cause
How do you know if you have damp? Apart from the obvious, there are certain things to look out for. However, the signs may indicate that it’s not a small problem you can resolve but rather a big issue that requires professional help.
Patches of black mould are a huge giveaway and can cause respiratory issues over the long term. Other indications of a problem with damp include peeling paint or wallpaper, crumbling skirting boards, tidemarks and salty deposits on the walls or floor.
Left untreated, serious damp issues can affect your property’s structure and stability.
Different Types of Damp
Before deciding whether your property needs damp-proofing, you need to determine what type of damp it is, the cause of the issue, and what you might be able to do to counteract it.
There are 3 types of damp; condensation, penetrating, and rising damp. Unless you know where the problem originates, it’s a good idea to go through a process of elimination first to avoid excessive and unnecessary expenses.
Condensation
With condensation being the easiest problem to resolve, it’s the obvious place to start. Moisture builds within properties lacking proper ventilation, resulting in mould spores and mildew.
Simple things like opening windows more often, drying clothes outside, and using extractor fans in bathrooms and kitchens help reduce moisture in the air.
According to Which? simply setting your heating to a lower temperature can help prevent damp. Another option is to invest in a dehumidifier to reduce and control humidity.
Penetrating Damp
As the heading suggests, there’s water coming in somewhere it’s not supposed to be. This could be caused by a range of problems, some of which can be rectified and prevented from happening in the first place.
Things you can check include guttering and downpipes. Blockages can cause rainwater to bypass pipes, resulting in prolonged contact with the external walls.
Furthermore, there may be hairline cracks in the rendering or brickwork, and moisture seeping into the structure of the building can cause significant damage.
If your property has a cavity wall, debris may be lodged between the outer and inner walls, creating a bridging effect. Similarly, cavity wall insulation could also pass moisture to the inner walls where the outer wall has deteriorated through driving wind and rain.
Other causes of penetrating damp might be leaks in the roof from missing slate or tiles. Internally, you could have an issue with a leaking pipe, cracks in the tiles or grout, or leaks from the shower or bath.
Rising Damp
Rising damp is generally caused by moisture below the ground, which rises and seeps into the walls. Though relatively uncommon, it is an issue that can cause complications and be the most problematic to deal with.
Check your existing damp-proof course, which should sit 150mm/6″ above ground level (see diagram above).
Building regulations made them compulsory for all houses built after 1875, so it may not have one if your property was built before then. There should be a thin strip or a grill at the base of the wall to indicate the presence of the DPC.
If the soil level is higher than the damp-proof course, this will need to be dug out again. Also, patios installed above the DPC will need lowering.
Damp Proofing Costs in 2023
If condensation, leaky guttering or missing roof tiles have been eliminated as the cause of the issue, you’ll need to consider other options. The type of treatment you need will undoubtedly depend on the severity of the problem.
Penetrating damp through porous bricks can be treated with a limewash or silicone water-repellent, still allowing the walls to breathe. Still, if there is an interim issue, such as wet cavity wall insulation, you must resolve it before any application.
Rising damp can be resolved by injecting a damp-proof course (DPC) chemical gel or paste into the base of the walls at a minimum of 15cm/6″ above ground.
It’s worth bearing in mind that depending on the severity of the problem and whether the floor is affected, it might be a case of repairing the existing damp proof course and membrane.
A chemical DPC is generally the most cost-effective and DIY-friendly type of damp proofing. The water-repelling chemical paste or cream is injected directly into the wall along the mortar course, as demonstrated in the video below. A quality DPC is effective in preventing damp from creeping up the wall IF this is the root problem of the issue.
Chemical DPC — Can You Do It Yourself?
While it’s possible to attempt this job yourself, I personally recommend hiring a professional. If you decide to DIY, you can expect to pay around £20 for a 310ml Dryzone cartridge — or around £30 for a 600ml cartridge. Remember to follow the instructions very carefully!
You may also need to remove and replace existing plaster and consider the costs associated with this job.
To determine the quantity of chemical DPC you need, use the table below as a guide. Prices and figures were obtained from householdquotes.co.uk.
| Width of Wall | Quantity | Area Covered |
| 4.5″ single wall | 1 litre | 9m2 |
| 9″ thick cavity or double solid wall | 1 litre | 4.5m2 (double if required on both sides) |
| 8″ thick filled or solid wall | 1 litre | 2m2 |
Other Tools You Will Need
- Safety Goggles
- Dust Mask
- Electric Hammer Drill & Masonry Drill Bit (12mm)
- Skeleton Gun (400cc or 1000cc)
- Plastering Materials
Before rushing out and stocking up on chemical DPC and other tools, you must be clear on your course of action. If you’ve checked everything, still can’t determine the exact cause of the problem, and aren’t confident in tackling the issue yourself, what’s the next step?
If you’re planning to go directly to a damp-proof specialist, you might want to get an independent damp survey done first, which will cost between £150–£300.
A surveyor will be able to conduct an investigation and discover the cause. They’ll also advise on a course of action and estimate costs, thus avoiding any potentially unnecessary and extensive work. At this point, you can then contact a professional to complete the work required.
The table below provides insight into the costs you could be facing for the more common problems and resolutions regarding rising and penetrating damp. The data shows costs for soil excavation, laying any external surfaces, new DPC, and silicone injection into the walls.
Prices are sourced from homeadviceguide.com. These prices will vary depending on your location within the country, the size of your property, and the work required.
Problem: Ground level higher than the existing damp proof course
| Work Required | Property Type | Cost |
| Ground excavation — one wall | Terraced | £200 |
| Semi-Detached | £290 | |
| Detached | £450 | |
| Ground excavation — whole house | Terraced | £330 |
| Semi-Detached | £540 | |
| Detached | £1,300 | |
| Ground excavation and installing gravel path — one wall | Terraced | £270 |
| Semi-Detached | £395 | |
| Detached | £585 | |
| Ground excavation and installing gravel path — whole house | Terraced | £350 |
| Semi-Detached | £820 | |
| Detached | £2,000 | |
| Ground excavation and installing concrete slabs — one wall | Terraced | £400 |
| Semi-Detached | £690 | |
| Detached | £1,400 | |
| Ground excavation and installing concrete slabs — whole house | Terraced | £760 |
| Semi-Detached | £1,890 | |
| Detached | £4,190 | |
| Ground excavation and installing concrete path — one wall | Terraced | £430 |
| Semi-Detached | £750 | |
| Detached | £1,190 | |
| Ground excavation and installing concrete path — whole house | Terraced | £850 |
| Semi-Detached | £2,110 | |
| Detached | £4,040 |
Problem: Damaged (or non-existent) DPC
| Work Required | Property Type | Cost |
| Silicone injection damp proofing — one wall | Terraced | £490 |
| Semi-Detached | £760 | |
| Detached | £2,000 | |
| Silicone injection damp proofing — whole house | Terraced | £900 |
| Semi-Detached | £2100 | |
| Detached | £4700 | |
| Insert new damp-proof course — one wall | Terraced | £290 |
| Semi-Detached | £425 | |
| Detached | £610 | |
| Insert new damp-proof course — whole house | Terraced | £395 |
| Semi-Detached | £920 | |
| Detached | £2,060 |
Tips for Obtaining a Quotation
- Get at least 3 different quotations for the work required
- Ask for a breakdown of the costs involved, especially if there will be additional/remedial work such as re-plastering or paving installation
- Ask for testimonials and reviews — quality experts receive positive reviews, helping you avoid unnecessary work and expense.
Don’t fancy doing this job yourself? Find top-rated damp proofing specialists in your area by clicking the button below:
Damp Proofing Cost — Final Thoughts
The above information should help determine the root of your problem and decipher the work required to make your home fully damp-proof. If there is an underlying issue of damp in your property, just papering over the cracks (so to speak) won’t solve the problem.
If you’re a property expert or DIY enthusiast, you might be confident enough to attempt a chemical injection DPC yourself. But for a big job that requires a professional, contact Rated People.