What Are the Different Damp Proof Treatments?

In 2021, the English Housing Survey reported damp issues in 904,000 homes. That’s not a small figure, which is why all property owners should be looking for an effective damp-proofing treatment.

That said, deciding on a damp-proof solution isn’t exactly a walk in the park. You’ll need to conduct thorough research to make the right choice, and we created this comprehensive blog just to help you with that. 

We’ll walk you through the common damp-proof varieties, when and where they’re used, factors influencing their cost and lifespan, and so much more!

Damp-proofing treatments, including Damp Proof Course (DPC), and Damp Proof Membrane (DPM). Learn how to tackle rising dampness and protect your property. Explore costs and DIY options.

Damp Proof Course (DPC)

A damp-proof course (DPC) is a treatment applied to all property types to protect them from damage posed by dampness.

You’ll find this treatment available in several forms, each with its own unique qualities and installation method. We’ll go over some of them in the points below. For now, let’s introduce you to the two main reasons we install a DPC.

  • Rising Damp: This is a major damp problem in which groundwater rises through the walls via capillary action. Water then seeps into various structural parts of the building, causing extensive damage. 
  • Penetrating Damp: This happens when moisture travels from the exterior wall to the interior due to accumulated rain or else. It’s one of the damp issues that are quite popular in buildings with walls made of porous materials such as brick, which can easily absorb water.

Damp Proof Membrane (DPM)

One of the most effective DPC varieties is the damp-proof membrane (DPM), which is also referred to as a damp-proof sheet. It’s a thin, water-tight layer laid beneath the concrete slab to act as a physical barrier. This way, it prevents moisture from penetrating the structure. 

Although DPM is available in several materials, polyethylene is the most commonly used due to its exceptional durability and water resistance. 

Damp Proof Injection

We usually use damp-proof injection when the original DPC of a property has deteriorated over time or is damaged. This treatment is one of the easiest to apply, and it effectively restores a wall’s ability to combat damp issues. 

To apply this DPC variety, we drill holes in the affected walls and inject a chemical solution into them. Within hours, this solution spreads horizontally within the brickwork, forming a long-lasting, water-repellent layer. 

Damp Proof Plaster

Applying damp-proof plaster is a complementary measure that we use in conjunction with DPC treatments. This means that these plasters won’t prevent damp issues on their own; a DPC must be installed. Now, let’s explain how they differ from traditional plaster. 

Plaster, in case you didn’t know, is a material used to coat walls, ceilings, and so on. When rising damp occurs in a traditional plastered wall, it leaves behind salt build-up and decay signs. 

This is because the groundwater that migrates up the brickwork carries salt that deposits on the plaster. How is salt harmful? It attracts moisture and water droplets in the air, which eventually causes water damage to the wall. 

Besides, regular plaster retains moisture for long periods, which hastens its deterioration. 

Whereas, damp-proof plaster is made specifically to resist salt contamination. It also has a porous composition that allows moisture to evaporate faster.

Damp Proof Paint

Damp-proof paint is another complementary damp-proofing method applied along with DPC treatments. We primarily use it to protect the appeal of the interior walls and ceilings of a property. 

You see, excess moisture can leave wet stains that ruin the interior aesthetic. So to avoid that, we apply damp-proof paint because it’s made with water-repellent substances and has a thick consistency that keeps moisture from surfacing.

Damp Proof Cream

Remember the chemical solution we discussed earlier in damp-proof injection? Well, that’s usually damp-proofing silicone-based creams that we inject into the walls. 

They’re chemically formulated to expand within the masonry and penetrate surrounding building materials to form a water-repellent barrier.

Damp Proof Spray

When you notice a damp patch on your wall or ceiling, you’ll first need to make sure that you address the underlying issue. Then, to permanently get rid of this spot, you can use a damp-proof spray. 

Damp-proof sprays are a quick fix for water stains and are fairly simple to use; you can apply them yourself. All you have to do is spray the affected area, and this will keep moisture from resurfacing. You can even repaint the wall after allowing the spray to dry for a few hours. 

We recommend you carefully read the application instructions on the bottle, as some sprays need to be applied twice for optimal results. 

Tanking Slurries

Tanking slurry is the main character in a waterproofing method called taking. 

When dealing with spaces prone to damp penetration, such as basements and cellars, we resort to wall tanking. The process entails either installing a water-proof tanking membrane or painting a tanking slurry on the wall’s surface. 

Tanking slurry, which also goes by cementitious tanking, is a liquid with a thick consistency due to the presence of cement polymers. Once it’s applied, it seeps into the pores of the masonry, effectively blocking them so that water can’t pass. 

What Are Damp Proof Treatment Uses?

In this section, we’ll take a closer look at when and where you’ll need to apply damp-proof treatments: 

Rising Damp

By now, you may have a general idea of what rising damp is, but let us explain more about how you can identify it. 

As we previously mentioned, this phenomenon occurs when groundwater starts moving upwards. Along its path, it leaves traces on the interior and exterior walls. So, if you notice any of the following signs on your property, make sure to have an expert inspect it:

  • Wet spots and salt deposits
  • Peeling wallpaper/paint
  • Rotting/decaying timber
  • Mouldy odour

After confirming that it’s a case of rising damp, the professional will recommend a suitable DPC based on the property’s condition and your budget. 

By the way, rising damp is more common in older buildings than in newer ones. Why? Because of two reasons. 

One, the DPC installed in older structures is more likely to wear out over time; two, there may not be one at all. To clarify, it wasn’t always a legal requirement in England for buildings to have a DPC to fend off rising damp, as it is now.

Internal Walls

It’s critical to protect your property’s internal walls from damp. Sometimes, they’re affected by the dampness of the exterior walls. Other times, they’re impacted by other factors, such as condensation caused by poor ventilation, roof leakage, and so on.

In all cases, we apply DPC to interior walls so they don’t develop any damp-related issues. Some of the treatments we use are a DPM, damp-proof injection, and taking slurries. Then, to ensure they preserve their appeal, we apply damp-proof plaster or paint.

External Walls

Water ingress is the most common damp problem that external walls face, but they’re also affected by rising damp quite often. 

Water ingress or penetrating damp happens in buildings for a variety of reasons. Some of the prevalent causes are rainwater accumulation, structural flaws, and faulty gutter systems. They all contribute to water infiltrating exterior walls. 

You can find these damp issues manifesting themselves on the wall’s surface as dark, damp stains and moss growth. To treat this, we use DPC varieties like the ones we apply on internal walls.  

What Damp Proofing Treatments Do You Need for the Different Surfaces?

Different properties are constructed with varying building materials. So, how do you damp-proof each one of them? Below, we'll explain the treatments appropriate for some of the most common materials and structures in a property.


Bricks are one of the most widely used materials for building exterior and sometimes interior walls in England. But, unfortunately, they’re prone to absorbing moisture, and if the brickwork wasn’t laid properly, damp seeps in even more.

To stop damp from affecting masonry walls, we use a DPM or tanking slurry. In case the existing treatment has failed, we inject a damp-proofing solution into the wall. 


Timber is frequently used in construction, whether for floors, columns, trusses, or a variety of other structures. 

As you may already know, wood generally doesn’t react well in the presence of damp. It soaks moisture up and can develop a serious case of rot, which can threaten the property’s structural integrity. 

Our go-to solution for keeping such a scenario at bay is adding a DPM. It’s important to note that if your property’s timber was severely rotted, you’ll need to replace the affected areas before damp-proofing. 


According to Approved Document C in the British building regulation, all types of walls should have a DPC installed under specific conditions. The major one is that we must apply a treatment made of water-tight materials, like polyethylene used in DPM, to interior or exterior walls. 

Aside from the legally required treatment, you can also apply damp-proof plaster or paint so you don’t have to deal with unsightly wet stains on your walls.


Floors in properties in England, like walls, are legally required to have a DPM installed with specific requirements. This applies to floors made of timber or concrete. 


Your ceilings may become affected by dampness for several reasons. It could be because of a leak in the pipework or the roof or maybe due to inadequate ventilation. 

Regardless of the reason, you must first address the root cause so you don’t have to deal with it again. After that, depending on the extent of the dampness, you might need to replace parts of the ceiling or simply coat the affected areas with damp-proof paint or spray. 

How Much Do Damp Proof Treatments Cost?

You can expect to pay between £300 and £400 to have a DPC installed on your property. However, there are multiple factors that can cause you to pay more or less, and the following are the main ones:

  • The DPC variety used, because, for instance, DPM will cost you more than damp-proof injection.
  • The size of the property or the number of walls that need to be treated.
  • The type of damp issue at hand, as some are more challenging to manage than others, necessitating more labour work. 
  • The severity of the damp case, because the earlier it's detected, the less collateral damage there will be, which means lower expenses. 

How Do You Install Damp Proof Treatments?

As you can see from the descriptions of the various DPC treatments above, they all come in different forms, which means their installation varies greatly. 

Should You Hire a Damp Proof Specialist?

Yes, in most cases, hiring a damp-proof specialist is your best bet. 

Professionals who specialise in damp-related issues are trained to thoroughly inspect a property and spot all warning signs, including those that are hidden from novice eyes. 

That’s why they have a better chance of pinpointing the root cause of the problem you’re facing and selecting an effective treatment for it. 

Besides, when you hire reputable damp-proof specialists, you won’t have to worry about sourcing high-quality materials or shopping for installation equipment. They arrive with all the necessary supplies to get the job done the right way. 

Should You Fix Dampness Yourself (DIY)?

Yes, you may be able to fix minor damp issues on your own. However, as explained above, it’s generally preferable to hire a specialist. 

That’s because if you misdiagnose the problem at your property or didn’t install the DPC properly, you’ll be doing more harm than good. The dampness may become more complicated and result in extensive structural damage. 

To contain the situation, you might find yourself paying far more than if you’d hired a professional from the start. 

All in all, if you’ve already had a specialist handle the problem and want to work on the interior aesthetics yourself, like applying damp-proof spray or paint, go ahead. Otherwise, we recommend saving your time, money and effort by leaving it to the professionals. 

How Long Does Damp Proof Treatments Last?

Damp-proof treatments can last anywhere between 20 to 30 years, with the following factors affecting their longevity:

  • DPC Type: Some DPC varieties are more durable than others.
  • Materials Quality: If the quality used is subpar, the treatment’s lifespan could be cut in half.
  • Installation: Precise installation results in a longer lifespan, whereas improper installation causes the treatment to deteriorate faster.
  • Maintenance: Following the proper maintenance requirements for treatments can help extend their life expectancy. 

Where Would You Typically Find Dampness?

Dampness comes with telltale signs that are usually found in specific spots in properties. To help you locate them, we’ve gathered below the main structures they appear on:

Damp-proofing treatments, including Damp Proof Course (DPC), and Damp Proof Membrane (DPM). Learn how to tackle rising dampness and protect your property. Explore costs and DIY options.

Internal Walls

The damp stains we find on internal walls reveal a lot about the main culprit. Here’s how:

  • Wet Stains at the Top: Damp patches on the wall’s upper part may refer to leaking pipes or damaged roofing.
  • Tidemarks at the Bottom: Dampness with salt deposits emerging from the wall’s lower part most likely indicates rising damp.
  • Random Dark Spots: Wet, discoloured stains that show randomly on a wall can point to condensation. 

External Walls

When external walls are affected by penetrating damp or rising damp, here’s how you can spot it:

  • Ascending Dampness: You’ll notice a wet patch starting at ground level and moving upwards.
  • Mould/Plant Growth: When you see mould or plants growing around or on the surface, it means that the wall has been soaking a lot of moisture. 

Residential Properties

Damp issues can show up in various spaces of a residential property, but the following two are the most likely to display them:


Traces of dampness in garages are fairly common, and there are plenty of reasons for that. Here’s where you can spot signs along with the potential cause:

  • Dampness on the Floor: Wet spots on the floor may indicate that rainwater simply entered from the garage door, or they may hint at a larger issue, such as a leak in the drain pipes.
  • Damp Stains on the Ceiling: Observing damp spots on the ceiling and sensing water droplets falling from above may point to condensation or roof leakage. 
  • Damp Patches on the Wall: Examine the direction and composition of the water stain and compare it to what we described above for internal and external walls. 


Dampness is frequently seen in basements, just as it is in garages, for diverse causes. Here’s how a couple of them manifest themselves in the space:

  • Constant Wetness on Floors: If the floors are always wet to the touch, this could indicate a problem with the pipework or plumbing below. 
  • Damp Walls and Ceilings: Excessive moisture on the walls, ceiling, and other surfaces may point to condensation. 

Commercial Properties

Make sure to check the internal and external walls of a commercial property for the damp indicators we mentioned earlier. You should also pay close attention to areas with poor ventilation as they’re susceptible to condensation. 

Final Word

Problems arising from dampness may initially appear harmless, then escalate to jeopardise the safety of both you and your family. 

To eliminate such issues once and for all, you’ll need to pin down the underlying cause and shield your home with the appropriate damp-proofing treatment. 
If this sounds like an overwhelming task to you, our experts at Watertight Homes would be more than glad to take it off your hands. Contact us today to schedule an appointment!

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