How Much Does Damp Proofing Cost?

What exactly is damp proofing? Damp proofing is a general term used to describe all of the available methods of preventing damp from being absorbed through the structural properties, floors, and walls of a property's interior.

If you leave damp for too long, it can eventually rot and can cause a lot of structural damage to your property. This is why damp proofing is so important. Any damp patches should be taken care of as soon as possible.

When a property is built, it is usually constructed with a preventative damp proof course built into the walls.

If you hire a professional to damp proof your home, they will usually do a few things such as inspect the walls, check the existing damp course, plaster the walls, inject a waterproof liquid, add waterproof render – these are just a few examples of what is usually included in a typical damp proof job.

The average cost to damp proof your home usually falls around £300-£2500. However, the overall cost that you can expect to pay will depend on various factors, including your home's size and your location in the UK.

If you are looking to damp proof masonry, brick, or concrete walls, a good method is to apply a tanking slurry. This is a waterproof coating that is made up of cement and acts as a barrier between any damp particles and your home structure.

Tanking slurries are most commonly found in basements, although they also work very well on the upper floors. If you wanted a professional to come in and apply a tanking slurry, this would usually cost around £30-£60 per square metre.

Another option you may wish to consider is having your interior walls re-plastered using a waterproof plaster mix. The average cost for this type of work is around £200-£400 per room, depending on the size of the room and your location in the UK.

Depending on how much work needs to be done, damp-proofing can take anywhere from 1 day to a week on average to complete. Re-plastering can be a messy job, so it is sometimes a good idea for you to move out while you're getting the work done.

Below is a table highlighting the average costs for different types of damp proofing prices:

TYPE OF JOB AVERAGE COST
Damp course – Terraced house £280-£370
Damp course – Semi-detached house £500-£800
Damp course – Detached house £1500-£2000
Tanking slurry – Terraced house £2450-£3500
Tanking slurry – Semi-detached house £2800-£3800
Tanking slurry – Detached house £4560-£6000
Re-plaster – Terraced house £1200-£1800
Re-plaster – Semi-detached house £1800-£2400
Re-plaster – Detached house £2400-£3000
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What are the Supply Costs of Damp Proofing?

There are only a few damp proofing options that you could carry out on your own. Most damp proofing jobs will need to be completed by a professional contractor.

If you were looking to attempt DIY damp proofing, you might need the following materials:

  • Damp Proofing Injection Cream - £5-£7 per 100ml
  • Anti-mould/moisture/damp proofing paint - £25 per tub

If you are hiring a professional contractor to carry out the work for you, they will usually use specialist materials. These materials are usually incorporated into the price of the job as a whole.

What are the Additional Costs of Damp Proofing?

When it comes to damp proofing, there are some additional costs that you may wish to consider with the job. These additional costs can include things that help prevent further damp in the future, or things that can improve the room after the existing damp has been taken care of.

Below is a table of the average additional costs that you may need to consider with this type of work:

ADDITIONAL COST AVERAGE COST
Extractor fan £150-£250
Dehumidifier £70-£100
Leaking roof repair £50-£100 per m2
Replacement gutters £480-£720
Window resealing £50-£60 per window
Door resealing £80-£100 per door
New doors £50-£1500 per door
New windows £200-£350 per window

Tradesmen Costs for Damp Proofing

A professional damp proofer will usually charge an average daily fee of around £100-£200. The amount of time that it takes to complete the work will depend on several factors, including the size of your home and the extent of the job.

Depending on these factors, damp proofing can take anywhere from around 1-5 days to complete.

Those based in London can also expect to pay more for labour costs than those based in other parts of the UK. If you are based in London, you can expect to pay an average of around £30-£70 more per day for labour.

How Long Does Damp Proofing Take?

The time it takes to complete the job will depend upon the type of damp proofing and your home's size. The damp proof course itself can usually be completed within a day. However, the contractor will then need to re-plaster the home, and this can take a few days to complete.

If a tanking slurry is needed to repair the damp, this can take a minimum of 2 days to complete as it needs a drying time of at least 24 hours between each coat. If you are having damp proof paint applied to the rooms in your home, this can take around 6-12 hours per room.

On some more extreme cases, your home may need to be rendered to prevent damp. This can take around 4-14 days on average to complete depending on your home's size.

Types of Damp Problems

Condensation, rising damp, and penetrating damp are the three most common types of damp that can affect residential properties. Each type of damp will need to be treated differently.

Below is some information on each of the different types of damp that could be affecting your home:

Condensation

Condensation is the number one most common type of damp issue in homes in the UK. This type of damp is caused by moist, warm air condensing on walls that are a cooler temperature. This is most common in rooms that naturally generate a lot of air moisture such as bathrooms and kitchens.

It most commonly becomes an issue in wintertime when the walls tend to be colder. However, it can be a problem in the summer months, too.

Central heating can often cause condensation damp problems. This is due to the fact that central heating gets very warm and then cools down again, causing warm, damp air that can lead to condensation. A lack of ventilation in the home can also make the problem worse.

If left untreated, condensation can cause your window and door frames to decay and can damage the paint and plaster on your walls. If you see condensation forming in your home, you should always wipe it away.

Symptoms of condensation damp problems include the following:

  • The appearance of dark mould – especially around windows or on glass.
  • An unpleasant smell of mould.
  • Water droplets appearing on the walls or windows.

Rising Damp

Rising damp is caused by groundwater that rises through a wall or floor. Walls will naturally allow a little bit of water in. However, this usually doesn't cause damage due to a damp-proof course or a damp-proof membrane.

Modern homes tend to have damp-proof courses and damp-proof membranes built-in. With this in mind, rising damp tends to be more common in older homes.

Rising damp can also become a problem when there is a lack of drainage or when the level of the ground outside your home sits higher than your damp-proof course as this will allow water to get above it.

Symptoms of rising damp problems include the following:

  • Paint and wallpaper starts peeling, often with wet patches.
  • Floor coverings may start to lift up.
  • Tide marks that rise up the wall.
  • Damage to plaster.
  • Damage to skirting boards.
  • A white, powdery substance on the wall due to soluble salt dissolved particles.

Penetrating Damp

Penetrating damp occurs when water leaks through the walls. This type of damp can expand across the walls and the ceiling. It is usually caused by structural problems in the building.

When your home has cracks in the walls or ceiling or problems with the roof or guttering, this can cause penetrating damp. When there are structural issues with the home, water can enter through cracks or leaks when it rains. Penetrating damp can also be caused by internal issues such as leaking pipes.

Older buildings are more prone to penetrating damp than newer buildings as newer buildings are often built with cavities in the wall to protect against damp.

Symptoms of penetrating damp problems include the following:

  • Damp patches on the wall which may become darker when it rains.
  • Damp patches on the ceiling which may become darker when it rains.

Types of Damp Proofing

There are several different ways that damp can be treated. Here are some details on each of the different methods:

Damp Proof Course

A damp proof course (DPC) is a form of damp proofing installed in a property to prevent damp problems from occurring.

There are a number of different methods of installing a damp proof course; however, the most common method is a damp proof injection.

A damp proof injection treatment involves the injection of a damp proof cream made up of a silicone-based liquid. This liquid reacts with the silica in the masonry to produce a layer within the wall that repels water.

Tanking Slurry

Tanking slurry is a relatively big job as it involves removing all of the plaster, debris, paint, and other materials from the wall surface. A salt neutraliser is then applied to the wall surface to prevent any existing salts in the wall from affecting the new tanking.

The wall is then dampened slightly, and holes are filled with cement, mortar, and a waterproofer. The wall is then dampened again before a tanking slurry is applied.

This needs to be left for 24 hours before another coat is added. The wall can then be re-plastered and decorated after the second coat is completely dried.

Re-plastering

If your walls need to be re-plastered, this will involve applying a layer of PVA initially so that the plaster dries out evenly. While the glue is sticky, the plaster will be mixed and applied to the wall.

Once the first coat of plaster is completed, it should then be left for 20 minutes before it is then skimmed and smoothed out, so there are no bumps. A second coat can then be added; however, this will be a much thinner coat than the first.

To finish off the plastering job, water will be applied to the surface to smooth out any bumps that may be on it. Sanding paper can then be used to smooth out and remove any excess plaster. Once plastering is completed, the wall can be re-decorated.

Benefits of Damp Proofing

There are several benefits to damp proofing your home. Below is a list of reasons why damp proofing your home is highly recommended:

Prevent Health Issues

Health issues can occur if damp proofing is avoided. Mould and mildew thrive in damp conditions, and mould can cause many health concerns, including wheeziness, headaches, coughing, and throat and eye irritations.

Damp-proofing your home will eliminate any potential for damp-related health issues and will help to keep your family safe and healthy.

Improve The Appearance of Your Home

Damp build-ups can cause unpleasant dark patches on your walls that can look very unsightly. It can also cause wallpaper to wilt and peel and can cause the paint to crack.

Damp-proofing your home will ensure this doesn't happen and you can decorate without the worry of any damp-related appearance issues.

Avoid Unpleasant Smells

Untreated damp problems can lead to unpleasant smells, especially when there is a lot of mould present. If left untreated, the smell of damp and mould can become overwhelming in your home.

If you go through a damp treatment process, this will eliminate all damp smells from within your home.

Avoid Reducing the Value of Your Home

Unless you get your damp problems treated professionally, they will keep coming back and could get much worse over time.

Damp can prevent future buyers from wanting to buy your home. Leaving damp untreated is a good way to put off potential buyers. If you damp proof your home, you can avoid this issue.

Prevent Structural Problems

Leaving damp area untreated can cause damage to the timbers in the structure of your property. Damp can cause the wood in your structural timbers to rot and potentially collapse. Damp-proofing your home can prevent any chances of rotting from occurring.

FAQs

Q: What causes rising damp in internal walls?

A: The movement of groundwater causes rising damp on internal walls up through the brickwork. This is usually due to leaks in the pipework within the home. Rising damp treatment can help to prevent any further issues from occurring.

Q: How do you seal a damp wall before painting?

A: You can seal your walls with a damp-proof sealant or damp-proof paint. This can act as a base layer before you paint over the walls for decorative purposes. Damp proofing walls before painting is a good preventative measure for potential damp.

Q: What causes damp on house walls?

A: Damp is usually caused by a build-up of moisture on the walls of your home. It can occur more commonly in some areas where moisture is present more commonly, such as in the kitchen or bathroom of your home.

Q: Is rising damp covered on home insurance?

A: In most cases, rising damp is not covered on your home insurance. However, every insurance policy is different, and you should check yours just to be sure.

Q: Can damp cause health problems?

A: Leaving damp untreated can lead to a number of health issues, including coughing, wheezing, congestion, and an irritated throat or eyes. It can also cause chronic health issues, such as reduced lung function or asthma.

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Sources

  1. https://www.which.co.uk/reviews/damp/article/dealing-with-damp/what-kind-of-damp-is-affecting-my-home-arNnf1P2wVnV
  2. https://www.petercox.com/our-services/damp-proofing/course
  3. https://www.mercianpreservationltd.co.uk/2019/01/23/what-are-the-advantages-of-damp-proofing-your-property
Author: Kim J

I have a bachelor's degree in Journalism, which I studied in both the UK and USA. I've been a freelance writer for over eight years and have experience working with many large brands. My experience in writing is over a wide range of different niches, and I've specifically worked in the DIY and trades section for nearly two years. My favourite thing about freelance writing is working wherever I want as I love travelling and discovering new places and cultures.