What Is Damp-Proofing and Why Would You Need It?

If you've been having moisture problems in your building, you might have had a few recommendations about damp-proofing your place. But what is damp proofing exactly, and how can it help with the water issues you're having? Also, how do you damp-proof your house?

If you're interested in finding out all of this, check out the headings below. We'll cover everything you need to know about damp-proofing from A to Z.

Damp proofing Rising damp

Everything You Need to Know About Damp-Proofing

Damp-proofing is the process of stopping moisture from getting to the walls, floors, and roof of your building by applying a damp-proof treatment.

But what causes dampness in buildings? And more importantly, how important is damp-proofing? Let's find out the answers.

Why You Should Damp-Proof Your Place

Unfortunately, bricks and concrete tend to attract water from their surroundings, especially the soil. That's why you usually see signs of dampness and even mildew on the lowest levels of buildings and masonry houses.

By damp-proofing, you make your building resistant to moisture, reducing the rate of water absorption and thereby preventing it from passing into the interior space and causing damage to your building. If it reaches too far inside your building, moisture can cause structural damage to walls and floors and promote the growth of mould.

The Culprits Behind Dampness in Buildings

Here's a brief roundup of the possible reasons behind moisture problems in buildings.


Many culprits can cause dampness in your building, but the most common is the surrounding soil.

Soil contains a certain degree of moisture which, due to capillary action, can travel up and through brick and concrete walls. That's why you usually see signs of dampness on the floor-level walls of buildings.

Sometimes, if the ground floor level is low, the filling in the plinth could cause dampness in the walls and flooring. The same can happen from the joints between the floors and the outside wall. Also, if the moisture is extensive, it can affect the ceilings.

Rain and Condensation

Another common source of dampness in buildings is rain. If the roof or the walls aren't impermeable to water, the rain will enter the structure and travel through it, causing damage to your building over time.

And even if your area doesn't get enough rain, dampness can still make its way into your building due to condensation. This happens when moisture is deposited on the walls, floors, and ceilings due to a drop in atmospheric temperature.

Other Reasons

A few other reasons for dampness in buildings include:

  • Faulty plumbing and poor drainage in bathrooms and kitchens
  • Sunken floors or bad tile installation that lead to the collection of water
  • Leakage through the roof slab
  • Flat roof slopes that cause water accumulation
  • Defective rainwater pipes
  • External vegetation
  • Low-quality concrete that absorbs a high degree of moisture

Note: With low-quality concrete, the signs of dampness may reach areas that are away from the leakage source.

How Dampness Can Affect Your Building

Many people think that some dampness is harmless, but in reality, it can cause many problems in buildings, some minor and some major.

For instance, the dampness can travel on and through the walls, causing ugly patching and ruining the overall aesthetic. It can also affect plaster walls, making them soft and causing them to crumble.

Dampness can also cause damage to your floor coverings and cause the actual flooring to get loosened when there's enough moisture to mess with the adhesive.

With enough time, it can also cause corrosion of metal fittings and deterioration of timber fittings. More seriously, it can damage the electrical fittings, which may cause electricity leakages and short-circuiting.

Additionally, the water can create unhealthy conditions that give rise to mosquitoes and fungi. It can also promote the growth of termites and certain disease-inducing germs.

Finally, the continuous presence of dampness in the walls may cause efflorescence. This will eventually lead to the disintegration of the bricks, tiles, and stones of your building, making it weaker and liable to collapse. 

damp proofing stages

Damp-Proofing Methods

There are plenty of ways to damp-proof your building, such as putting plastic sheets and sand under floors, adding waterproof compounds to your concrete mix, or applying an impenetrable substance to the building surfaces. To know the best treatment for your place, you can hire a damp-proofing company to do a damp inspection and consider their recommendations.

To help you visualize, here are a few methods commonly used nowadays for damp-proofing.

Liquid Wrap and Joint Filler

First off, you've got the liquid wrap and joint filler damp course. The liquid wrap is a polymer that's applied over the areas requiring damp-proofing. However, before applying it, you first need to prep those areas using a waterproof joint filler to close any cracks, seams, or holes you encounter.

Flashing Materials

You can damp-proof your house by using flashing materials, which are damp-proof membranes made of polyethene foil. These membranes are impermeable to water, repelling it and preventing it from passing into your building. Best of all, they're easy to apply. You prime your walls, then apply the damp-proof membrane using a trowel, roller, knife, or caulk gun.

Damp-Proofing Creams or Rods

Next up, you've got damp-proofing rods. These are rods made of a silane/siloxane polymer with water-repellent qualities. Once installed, they can stop dampness from travelling up your walls by capillary action.

Damp-proofing creams also work in the same fashion. They're made of similar ingredients and have the same properties as the rods mentioned above. They're even applied the same way, where you drill holes in a mortar joint and then fill them up with the cream/rods.

Damp-Proof Sheeting

Lastly, we have damp-proof sheeting. This is a durable, waterproof membrane placed to prevent water and vapour from rising through the ground and travelling inside concrete slabs.

Accordingly, you can preserve your walls and floors from water damage and improve your indoor air quality. And as a bonus, you also end up with a barrier to radon and methane gas.

The Process of Damp-Proofing

The damp-proofing process will differ depending on the material you'll use.

For example, if you're installing a damp-proof membrane, you first need to remove the old plaster until you reach the original masonry. Then, you'll cut the damp-proof membrane to the size you need and place it on the wall.

You'll also drill it to the wall and secure it with special membrane fixing plugs to ensure a tight fit. Finally, you'll go over all the joints and overlaps with membrane-jointing tape to prevent any possible leakages.

As for damp-proof paints, you apply them as you would regular paint. Now, you can apply the paint on top of the plaster, but over time, the gypsum will degrade when the water locks into it. That's why it's best to apply the paint to the original masonry/concrete and then cover it with plaster or render.

A tanking slurry should be applied in the same way. Just get to the original masonry, apply a couple of coats of the slurry on it, and then cover it up with a new render. As opposed to paints, the tanking slurry can withstand large water pressures, which is why they're usually used for damp-proofing basements.

Sometimes, owners will remove the existing render/plaster and replace it with a water-resistant render. This will keep the moisture from passing to the new finishes and allow the wall to dry over time.

An Overview of Damp-Proofing Treatment in Buildings

In buildings, you need to damp-proof many different parts.

First off, there are the foundations. Since the basement foundation can receive water from the adjacent external ground, you need to damp-proof your building's foundation against gravitational water. You also need to damp-proof your basement by installing foundation drains, RCC rafts, and damp-proof material.

After that, there comes the damp-proofing of floors. Usually, this is done by spreading a thick layer of sand under the floor, followed by a damp-proof sheet or membrane.

As for the walls, a damp-proof material is applied to the external and internal walls, about 15 cm above ground level. Once this is over, the roofs are the final step in the damp-proofing process to protect against rain-induced water damage. 

How to Protect Your Building from Moisture

There are a few steps you can follow if you want to protect your building from moisture. For one, ensure you've got good ventilation to minimize internal and external condensation.

You should also properly maintain the outside of your property, monitoring any vegetation that's too close to the building walls. More so, make sure your rainwater and drainpipes are in order and regularly check your windows and doors for any defective seals.

As for the damp-proofing itself, ensure you seal all penetrations before applying the damp-proofing material and ensure all surfaces are clean and dry. Lastly, if you don't know how to apply your damp-proofing material properly, we recommend you hire a damp-proofing specialist for the best results. 


As you can see, damp-proofing is an integral step in the maintenance of any building. Not only does it protect your building from a myriad of problems, but it also protects your health from mould and rot.

Accordingly, if your building hasn't been damp-proofed, you should get right to it. You can contact a professional or do it yourself if you know how. Thankfully, you can find numerous damp-proofing materials nowadays that are easy to apply.

So, protect your walls and floors from falling apart and begin your damp-proofing journey right now!

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