Damp Proofing Cost Guide: How Much Does it Cost to Damp Proof a Wall

On the face of it, a seemingly simple question like how much does it cost to damp proof a wall should have a simple answer. Yet if you’ve ever tried getting so much as a rough estimate from a contractor, you’ll soon find that damp-related property damage can be a complex problem with no one-size-fits-all solution.

As we’ll discuss in today’s guide, there’s a whole world of difference between sorting out a minor condensation problem and adding a whole new damp proofing cost to eliminate the ugly and potentially dangerous problem of rising damp.

Still, just because things aren’t quite as straightforward as you’d like, that doesn’t mean you can’t get an answer to your question.

Below, we’ll look at three most common types of damp and how much it costs to both repair the damage caused and prevent it from happening again.

Before we get to that, however, let’s quickly touch on why damp proofing is so important in the first place.


Left untreated, damp can cause serious damage to any property. In today’s guide, we look at the cost of preventing that damage by protecting against the three major types of damp.

Why You Need Damp Proofing 

If you currently have damp in your home, then you don’t need us to tell you what an unattractive nuisance it can be.

Even if it’s only a little bit of mold caused by condensation, it can be a major blemish on the look and feel of any room. More often than not, it can cost less to invest in a good damp proof course than it would to spend years continually cleaning up the mold and redecorating whenever it gets out of hand.

That’s to say nothing of the health problems that even minor amounts of damp can cause.

Respiratory problems, lung infections, and headaches are all symptoms of exposure to damp and mold. What’s more affected areas often prove to be an ideal breeding ground for dust mites, bacteria, and all manner of household bugs.

For those reasons alone, damp proofing the walls of your home is always a good idea, but we’d be remiss if we didn’t at least touch on the kind of long-term damage untreated damp can do to the structure of your property.

The International Residential Code (IRC) is a set of standards relating to the safety, accessibility, and energy efficiency of modern homes across 49 US states. In one section, the IRC insist that in order to be compliant, any foundation walls which “retain earth enclose interior spaces and floors below grade” all need to be fully damp-proofed.

This is because any damp-based damage you see on the surface could be a sign of much bigger problems going on within the structure of your home, causing rotting and degradation that could lead to the whole property being unsafe.

How Much Does it Cost to Damp Proof a Wall? 

Mold like this may be a sign of condensation or penetrating damp, which is generally cheaper to fix than damage caused by rising damp.

Your damp proofing cost can vary greatly from as little as $200 per wall to upwards of $2,000 per wall. 

While the size of your wall no doubt plays a part in determining how much you actually pay, it isn’t the biggest influencing factor in the same way that it is with other wall treatments such as rendering.

Instead, the question of whether you ultimately spend a few hundred dollars or a few thousand, all comes down to one key factor:

The kind of damp you have in your home and the amount of damage it has done. 

On the whole, there are three main kinds of damp that could affect your home:

  1. Condensation
  2. Penetrating damp
  3. Rising damp. 

Each one requires a different solution ranging from some basic redecorating for condensation all the way to structural changes and expensive damp proof courses for severe rising damp. 

Below, we’ll talk you through each of the main kinds of damp, how to identify them, and how much a solution may cost you.

The Three Main Types of Damp Proofing and Their Costs 

If you have a problem with condensation, most of your costs will be in redecorating damaged walls like this one.

Condensation (average cost to damp proof: $50 – $200)

Condensation is a bigger cause of damp in modern homes than just about anything else. 

It is most common in rooms that are kept at low temperatures or that have poor ventilation, though it can also be caused by the steam from cooking, from showers, and from hanging wet clothes around your home to dry. 

How to Identify Condensation:

The good news is that condensation is pretty easy to spot. The bad news is that it can be fairly unsightly. 

On windows, ceramic tiles, and similar non-porous surfaces, you’ll find small droplets of moisture hanging around. While this isn’t too much of a problem, condensation damage gets worse once it gets onto your walls, baseboards, and other surfaces.

There, the damp can cause mold to form which not only adds an ugly look to your home but can also cause a variety of health problems

Methods and Costs for Treating Condensation

Fortunately, there’s more good news when it comes to protecting your home from condensation damage: 

It’s very easy and very affordable. 

You can clean your baseboards and other surfaces using either common dish soap or a white vinegar solution. From there, buying a low-cost dehumidifier to improve the humidity of your home and keeping a comfortable temperature should be enough to stop the issue recurring.

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All in all, that simple solution should set you back no more than $50 – $60.

However, if the mold has spread and caused some major cosmetic damage then it may be worth redecorating, a process that could cost between $100 – $200+ depending on whether you do it yourself or bring in a contractor.

If you’re going down this route, then you’d be as well investing in some good quality damp proof paint such as Rust-Oleum’s Mildew-Proof Performance Paint rather than just standard house paint. That way, you can be sure that even if condensation does reappear, your walls are well protected from any damp or mold.

Penetrating Damp (average damp proofing cost: $150 – $800)

One of the biggest costs of damp proofing to protect against penetrating damp may be hiring a roofer to fix cracked, loose, or badly-fitted roof tiles

After condensation, penetrating damp is the second biggest cause of damp-based damage in the home. 

There are two different types you need to be aware of here, lateral and vertical (also known as ‘falling’) penetrating damp. 

The former is most common on exterior walls, especially those that are exposed to harsh weather conditions and torrential rain. The most frequent causes of lateral damp include cracked or poor quality brickwork or problems with the seals on your windows and doors which allow rainwater into your home.

Though it may start on the external walls, lateral penetrating damp can begin creeping into your home if left untreated.

Vertical penetrating damp is almost the same though, as the name implies, it penetrates your home from top to bottom rather than from the sides of your property. Vertical damp is even more common than the lateral variety as it is usually caused by faulty or blocked guttering, broken roof tiles, and problems with your guttering.

How to Identify Penetrating Damp 

The most obvious sign that you have a problem with penetrating damp is that you have watermarked walls or other clear signs of water damage on the inside of your property.

Unlike rising damp which you’ll generally only find at the bottom of the room, penetrating damp can cause these unsightly water stains anywhere on the wall. 

Depending on how severe the problem is, you may also see visible water droplets on the surface of your walls, as well as signs of mold.

You may also notice damp smells in the room, though this can also be a symptom of rising damp, so it’s better to rule that out before you figure out the best way to fix the problem.

Methods and Costs for Treating Penetrating Damp

If you’re certain that penetrating damp is your problem, then your first priority should be to identify and fix the source of that problem.

Remember, this type of damp is always caused by some kind of defect on the outside of your property, so take a good look around for signs of blocked or leaking gutters, damaged pipes, or cracks in your walls.

These kinds of damages should cost you anywhere from $50 to replace a single section or fill in a crack in the wall to $200+ if your entire guttering needs replacing.

Be mindful too,  that penetrating damp could come in from a badly-fitted tile or a window seal that has seen better days.

In the case of the latter, you may benefit from replacing your entire windows, which could cost between $300 and $1,000. 

For your roof, you could repair the damage yourself if it’s as simple as replacing a loose tile, though for major work you may find it safer to call on a professional. 

Having fixed the source of the damp, your next task should be to take preventative measures to stop it happening again. Applying a waterproof seal such as Rust-Oleum’s LeakSeal Flexible Rubber Coating will prevent damp by creating an impenetrable, water-repelling barrier. 

The good thing about these types of coats is that they’re completely transparent, so you can rest assured that they won’t affect the external appearance of your property.

Finally, if that penetrating damp has caused damage to your walls or ceilings, then you may have to break out those paint brushes or rolls of wallpaper and invest some time and money on redecorating.

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Rising Damp (average damp proofing cost: $300 – $2,000)

Rising damp can seriously ruin the aesthetic of your home, making it essential to get it fixed

Third and finally, we come to the least common yet most problematic type of damp problems – rising damp, which is exactly what it sounds like:

Moisture rises up from the ground into your walls and can not only seriously mess up your interior design but also wreak all kinds of havoc with the structural integrity of your property. 

Occurring much more frequently in older buildings than modern developments, rising damp is typically the result of a poor quality or non-existent damp proof course.

When most modern homes were developed, damp proofing materials would have been built into the brickwork and foundations to stop moisture from soaking through.

However, if those materials are ineffective or -in the case of many older properties- weren’t installed in the first place, then rising damp can cause a major headache.

How to Identify Rising Damp

When it comes to this kind of damp, there sadly isn’t a lot of good news, though if there is any kind of positive here, it’s that there’s no mistaking rising damp when it does occur.

Visibly, you should be able to see a very clear damp line on your internal walls which could reach as high as three feet. Unlike penetrating damp or condensation, rising damp is unlikely to have any mold, though some salt minerals may be visible and can be felt if you run your hand over the damp area.

If you suspect that you have rising damp but the damp line isn’t prominent, it might be a good idea to spend a few dollars on a digital moisture meter and run it against the damaged wall.

If you do have rising damp, you’ll find that the meter gives out a much higher reading towards the bottom of the wall than it does higher up.

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Methods and Costs for Treating Rising Damp

The most common way of solving rising damp in a home is to inject a Damp Proof Course (commonly known as a DPC) directly into the walls. This can cost anywhere from $300 to several thousand pounds depending on the size of your walls, how many walls you’re having damp-proofed, and how much repairing and redecorating work has to take place afterward.

If you’re working on a new build property or renovating an old home that requires structural changes, you’ll save money by having a DPC installed as your walls are being developed as there will be little -if any- need to replace plasterwork afterward.

If, on the other hand, you’re working with existing walls that either doesn’t have a DPC or have one that isn’t working, your costs will be higher.

This is because, with existing walls, your damp proofing specialist will need to spend time first taking out any affected drywall, drilling holes into the walls, and then plastering over everything again. That’s not to mention the additional costs of any redecorating work you need to do.

Chemical DPCs ($300 – $450 per wall)

Chemical DPCS options are by far the most common damp proof course solutions in 2020. 

To do this, a professional contractor will drill holes that are roughly half an inch in diameter into your bricks, they’ll then use these holes to inject the solution -which is usually silicon-based- directly into the walls.

While that is simple and affordable enough, you may end up paying much more  if those salt minerals have soaked into your drywall. If that’s the case, you’ll have to have that drywall taken out and replaced, preferably using a waterproofing bonding additive as part of the plastering process to prevent a recurrence of the problem.

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Damp Proofing vs. Waterproofing – Which is the Best Option for My Home

If you’re converting your basement into a living space or bedroom such as this one, you may need to invest in a full waterproofing solution rather than just damp proofing

The biggest difference between the two is how much protection they add to your property.

A damp proof course will protect your home from soil moisture, but only waterproofing will protect your home from both soil moisture and liquid water such as rain. 

As we mentioned at the start of this guide, the IRC requires all walls which “retain earth and enclose interior spaces” to be damp proofed, while stating that waterproofing is only required in areas which have a high water table or “other severe, soil-water conditions.” 

It’s for this reason that waterproofing is more commonly applied in basements where there is a higher risk of flooding and other water damage, while damp proofing is better suited as a whole-home solution.

Finally, it’s worth mentioning the cost difference. 

While it only costs $4 – $8 per square foot to damp proof a wall, waterproofing is likely to set you back $6 – $10 per square foot.

Frequently Asked Questions About Damp Proofing

As eager as you might be to decorate, you’ll need to wait until your damp proof course is fully dried before you can break out those paints and paint-rollers

How Long Does it Take to Damp Proof a Wall?

Most contractors take between three and four days to install a chemical damp proof course across an entire home.

Obviously, if you’re just having the one wall damp proofed, it should be done much quicker.

As a general rule, budget around half a day for smaller walls and a full day for larger ones. 

How Long Does Damp Proof Take to Dry?

Though it may not take long to install, a damp proofing course can take a very long time to fully dry out. 

If your walls were originally affected by rising damp, expect it to take at least six months before that wall is fully dried out and ready to be decorated. 

If you’re applying damp proofing as a preventative measure, it may still take as long as two-three months for your walls to dry. 

What’s the Best Way to Decorate Damp-Proofed Walls?

First things first, it’s essential that you wait until your damp proof course is completely dry before you start painting or wallpapering.

Although that can be frustrating if you’re in a hurry to get your renovations finished, applying paint or wallpaper to walls that haven’t finished drying could not only hinder the drying process even further but cause unsightly damage to your finished walls which leaves them looking even worse than before.

Regardless as to whether you’re painting or papering, you’ll benefit from first applying an undercoat using a water-based primer like Zinsser’s all-surface interior and exterior primer.

This allows both wallpaper and vinyl or acrylic paints to adhere better to your newly damp-proofed walls without seeping into the walls and creating a mess.

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Final Thought: How to Save Money on Damp Proofing Cost for Your Walls

There’s no escaping the fact that the cost of damp proofing a wall can be pretty expensive, especially if the problem has spread across multiple walls and is beginning to make your home almost unlivable. 

Yet rather than wait until your damp problem becomes a critical issue, you’ll find that taking good care to prevent that damp from building up in the first place could save you hundreds, if not thousands of dollars.

Keeping a steady, comfortable temperature, ensuring your home is well ventilated, and buying a dehumidifier to eliminate moisture from the air will all work wonders in keeping that pesky condensation at bay.

To prevent a build-up of penetrating damp, invest some time in carrying out simple household maintenance tasks such as clearing out blocked gutters as well as regularly inspecting your property for broken pipes, leaking gutters, or cracks in the walls.

If you live in an area with lots of rainfall and find that vertical penetrating damp is caused by rainwater spilling out of overflowing gutters, you might want to consider investing in a rain barrel to redirect some of that excess water.

Finally, while rising damp can be the hardest type to avoid, it can be addressed by re-rendering the outside of your home.

If you currently have a solid, cement render in place, any moisture that rises up from the ground will get trapped in your walls. Replacing this with a lime-based solution will give your home some much-needed breathability so that moisture can escape without causing any damage.

While adding a whole new render may not be the smallest job, the rest of these steps are small, simple actions you can go a long way to keeping your home free from damp without spending a fortune.

CANVA Image How Much Does it Cost to Damp Proof a Wall