Damp external wall: How Do I Protect My Outside Wall From Damp

How Do I Protect My Outside Wall From Damp

Damp on external walls is a common problem that can stem from a number of issues.If not treated properly, it can lead to even more problems down the line. That’s why you should be proactive and install the right protective measures to save money and keep your home warm and dry.

In this guide, we’ll cover how to protect your outside walls from damp with a bit of DIY and the right tools. We’ll also take you through dealing with an existing damp wall by fixing the root cause of the damp before making good and installing the right damp protection.

Protect against damp with exterior wall waterproofing

Most methods for protecting against damp externally are relatively simple DIY tasks, such as applying facade cream or installing a new damp proof course. If you’re already suffering from a damp exterior wall, it’s important to fix whatever it is that’s causing the damp. This could mean fixing leaky gutters or pipes, replacing old, crumbly mortar or even carrying out crack stitching repairs. How you implement external wall damp proofing will depend on the type of damp you have.

Regular inspections of the exterior of your property are vital to protecting your home from damp and structural issues, especially on external walls. It’s best to have an idea about the different types of damp and what they look like, so you can spot the warning signs and identify the issue quickly. Our external property maintenance guide summarises some of the common damp and structural repair issues, including what to look for and how to fix them.

One of the main ways of protecting against damp is preventing water ingress through walls, which can happen through old, failing mortar or simply heavy rain being absorbed by brickwork and masonry. We’ll look at how you can sort these issues below.

Repairing and replacing mortar

Poor, crumbling or non-existent mortar can accelerate damp on an external wall as it allows water to seep through to the inside of your home. It’s best to repair or replace old mortar if you’re prone to damp problems.

  1. First, remove old mortar to at least 10mm depth
  2. Use a mortar mix that’s appropriate for the age of the property and isn’t too strong for the surrounding brickwork. Apply using a trowel.
  3. If the mortar is in too poor condition across the entire wall, then we’d recommend raking out and replacing all of its front section, rather than just doing a patch repair.

Once cured, the wall is ready to receive water repellents for damp proofing your exterior walls.

Protect from damp on external walls with water repellents / facade creams

Now that your exterior walls are free of defects, you can install external damp protection. Water repellents protect masonry from penetrating damp, freeze thaw and structural damage, and can be applied quickly and easily. They’re a cost-effective way of preventing more costly issues later down the line.

We stock market-leading water repellents, including:

  • PermaSEAL Facade Cream


  • Microshield Ultra Masonry Waterproofing Cream

With these exterior wall waterproofing creams, water beads off the wall instead of soaking into the brickwork.their cream consistency provides better absorbency of the active ingredients, ensuring long-lasting damp protection. This also means that none of the product goes to waste as it avoids runoff.

You only need one coat for long-lasting protection – PermaSEAL Facade Cream lasts for 20+ years, whereas Microshield Ultra lasts for 20-30. For more info on water repellents, read our guides on:

  • Treating penetrating damp with water repellents
  • Masonry and brick waterproofing

I have damp on my outside walls – how do I fix this?

Dampness on outside walls is a common problem – but the good news is that there are various non-invasive ways to sort it. Permagard have the tools and guidance needed to help you get the job done. Keep reading to identify your damp problem and see what you need to fix it.

The importance of solving damp external wall problems

Masonry and brickwork is porous and absorbs water from heavy or driving rain as well as any other water source. This makes it easier for water to travel through brickwork, penetrating deep into your building substrate and causing a variety of damp and structural problems.

Leaving damp issues unsolved can then lead to:

  • Damp and mould on internal walls
  • Freeze thaw damage to brickwork
  • Structural issues & damaged timber
  • Damaged brickwork, which can be costly to fix
  • Heat loss and therefore higher energy bills

The longer you leave your external damp issue, the more problems you’ll have to deal with down the line. Ideally, you should install protective measures so you never actually see signs of damp in your home. It’s never too late however, and once you’ve fixed your current damp issue there are proactive steps you can take to prevent it from happening again.

Why are my external walls damp?

There are several reasons why you could be seeing damp on an external wall:

  • Heavy/driving rain that’s been absorbed into your brickwork
  • Cracks in walls/building faults, as crumbly mortar or missing render
  • Plumbing issues creating a constant source of water
  • Leaky or overflowing gutters or downpipes causing water to stream down masonry
  • High soil levels, which can lead to a bridged DPC
  • You may not have a DPC or have an old one that’s no longer working.

You must diagnose the cause of damp patches on external walls in order to fix it correctly. It always makes sense to consult a professional for a correct diagnosis.

What does damp on outside walls look like?

The first step in treating damp on external walls is to identify the type and put the right fixes in place. We’ve gone into detail about identification and the causes of damp in our guide, but here’s a few signs to look out for.

The signs of damp on external walls can include:

  • Damp patches on exterior walls
  • Damaged brickwork
  • Algae and moss growth
  • Salts on external walls
  • Crumbly or old mortar

You may spot damp on internal walls first. If you see:

  • Damp patches, tide marks or peeling paint on your walls
  • Salts on walls
  • Condensation on windows
  • Musty smell

Then you’re likely experiencing damp issues. Each symptom points to a different type of damp, such as penetrating or rising damp.

Penetrating damp on external walls

Penetrating damp is caused by water entering your home through a building fault, such as cracks in your walls, leaky pipework or plumbing issues. It can also be caused by heavy rain. Water seeps through the building, leading to internal mould growth. It can also result in freeze-thaw in your brickwork over winter. This is when water gets into the brickwork, freezes and expands. This causes the pores and cracks to allow more water in and the cycle to continue causing more structural damage that can be a costly issue to fix.

Penetrating damp can also impact the thermal performance of your property as damp walls encourage heat loss, increasing your energy bills in turn. The longer penetrating damp is left, the weaker your overall building facade becomes, so it’s important to take the proactive steps needed to ensure you don’t have to deal with penetrating damp.

Rising damp on external walls

Rising damp is a rare form of damp that is often first noticed on internal walls. It occurs when water rises through the brickwork in capillary action. It is the result of a failed or non-existant damp proof course (DPC), or when the DPC has been bridged, possibly because of building works in your garden. Without a DPC there’s nothing to prevent water from travelling up your walls.

Before fixing rising damp, it’s important to confirm your diagnosis with a professional – as it’s a rare form of damp it can often be misdiagnosed. Read more about rising damp in our guide.

Solving the root cause of external wall damp and repairing cracks in walls

Before you can start installing protective measures, you first need to fix the source of the damp – need to ensure you’re treating it correctly. So, say your cause of your damp external wall is leaky or blocked guttering, you need to get it sorted ASAP.

This also applies to any cracks in your walls. A wall crack is the perfect opportunity for more water to penetrate your home, leading to penetrating damp and freeze thaw damage. Most cracks can be repaired using helical bars, a cost-effective way of restoring structural stability for years to come.

At Permagard, we offer helical bars in a variety of lengths, quantities and thicknesses. They can be purchased on their own or as part of our popular crack stitching kits – the Easi-Fix Crack Stitching Kit and the Easi-Fix Heavy Duty Kit, designed for larger cracks.

Crack stitching can be done without a professional, but you will need to read the instructions carefully to ensure that the bars are correctly installed. We’d still recommend having a professional confirm the type of crack and assess structural stability before you decide on treatment. Our guide to fixing wall cracks goes into more detail about the different types, causes and how you can use our helical bars to restore your external wall.

If you’re seeing cracks around windows and doors, this could be due to lintel failure. Lintels are installed around doors and windows for extra support around these openings, however overtime they could corrode or become cracked as your property shifts. Helical bars can also be used for lintel repair – read our guide on replacing lintels to see how.

Can I inject a damp proof course from outside?

If the damp patches on external walls are due to rising damp, then you may need to install a new damp proof course (DPC). A chemical damp proof course can be installed from outside, however you will need to re-render once the new DPC is installed. This ideally shouldn’t be applied over the DPC unless the render you’re using is waterproof.

As we mentioned earlier, first confirm your rising damp diagnosis with a professional before starting treatment.

Damp proofing injection cream is a cost-effective and fast way to treat rising damp on external walls. It’s designed to penetrate the mortar, which then absorbs the product and lines the capillaries, forming a new water repellent barrier that provides you with peace of mind. For step-by-step instructions on applying damp proof cream, click to read our guide.

Kiesol C Damp Proof Cream is the highest strength damp proofing cream on the market, and here at Permagard we sell the product either on its own or as part of a handy all-in-one kit. Kiesol C is a clean and simple method of damp proofing external walls, creating a long-lasting barrier against rising damp. Find out more about our DPC Cream Kit here.

Damp proofing exterior walls

Remember, only once the source of damp is solved can you start damp proofing outside walls and using protective measures. If you are seeing damp patches on external walls, then you’ll need to start by identifying the type of damp to make sure you solve the issue correctly:

  • Importance of solving damp external wall problems
  • Why are my external walls damp?
  • What does damp on outside walls look like?

External damp proofing with Permagard

If you’ve spotted damp on your external walls and are unsure of what steps to take, Permagard can help. Speak to our team for technical support so you can get the job done. Call us on 0117 982 3282 or email at: [email protected]

Damp Proofing External Walls: Top Tips and Tricks

Picture the scene: You know that your masonry is in serious need of an update, but like most things in life, the task facing you seems overwhelming.

Should you chance a D.I.Y attempt, or is it better to leave it to the experts?

Yes, you can always go to the store, buy some products, power wash your outside wall, and try to do it yourself. But if not done properly, damp proofing external walls is useless. In other words, you may be able to pull it off in practice, but long-term, it won’t be nearly as effective as when a contractor installs it correctly.

Damp proofing walls will protect your home from moisture, and any resultant damage from damp. Exterior walls that are made from concrete, bricks, and similar material are porous. In other words, they invite moisture if not untreated. Here’s how the process goes…

Damp Proof External Walls: Key Causes

Before you start thinking about insulation and damp proofing, you need to understand what type of damp you are faced with. There are two main types of damp, rising damp, and penetrating damp.

Check if there is a damp proof course installed in your home. If there is not damp proof course that is properly bridged, you will notice salts on the inside of your walls.

These salts make up a crystallised powder, that appears on plaster if there is no protection against rising damp. The plaster usually requires removing, and a new damp proof course needs to be installed.

Penetrating damp, or condensation, manifests as black mould and spots of mildew. Sometimes, mould is accompanied by musty smell and there is something against the wall. One of the solutions for penetrating damp is better ventilation, but damp proofing external walls is a much more efficient solution.

Should you Do It Yourself?

We mentioned at the beginning of this article that sometimes, damp proofing can be done as a D.I.Y project. But we are highly against it. We recommend you never do it on your own.

The reasons are many, but for starters, damp proofing requires usage of special chemicals. They need to be carefully handled, and they can be dangerous.

Yes, buying a silicon gun and products in tubes might be a cheap solution. But ask yourself, would you really like to do it over and over again until you get it right?

The Problems with Damp

There is a reason why damp proofing external walls is important. Damp and mould can be serious problems, with hazardous implications for your health. The problem occurs when your external walls are exposed to water.

This is usually rain, but it can be from another water source as well. The water can enter your masonry, and travel laterally form the external, to the internal walls. If there are cracks in the bricks, they are letting the water in.

In some cases, if there is a constant flow of rain, your walls might stay damp, and not get the opportunity to dry out. As a result, your home’s thermal conductivity is radically reduced.

Cracks in pointing and brickwork affect the overall water absorbency of your walls. Different areas absorb water differently, with some absorbing more than others. The result is damp patches, due to penetrating damp.

In other instances, some areas are more exposed, or more susceptible, to water, and the result might be a large, damp area appearing. The dampness can spread to the internal walls, resulting in damp patches inside as well.

Damp patches contain salts that have washed out of the brick. They can erupt through the paint, and blow the plaster. Sometimes, damp patches are cold spots on the wall.

As a result, you lose 3 times heat faster than the surrounding wall. Cold spots allow even more moisture from your internal air to form condensation. In the spirit of the “rich are getting richer” your damp walls are getting damper.

As for damage to the external walls, when water gets into the brickwork, cracks appear. The action, referred to as the ‘freeze-thaw’ effect, allows more water in, gradually making the problem worse with each passing day. And mould can grow on the outside walls as well, further reducing the visual appeal of your home.

One outer wall of the bath constantly damp

  • org/CreativeWork”>


    One outer wall of the bath is constantly wet

    I found myself in such trouble. One outer wall of the bath is constantly wet, and there are no visible sources of moisture near this wall. Neither inside nor outside. What is this?

  • #2

    Maybe just slanting rains more often in this direction? Pay attention to the same wall when there will be no rain for a long time. This summer is especially rainy.

  • #3

    I also immediately had the thought of oblique rain. And the canopy over the roof can be different. On one side there is a porch, on the other side there may still be a tree … pay attention to this.

  • #4

    Well, yes . .. if the wall is wet after the rains, then this is clearly the reason. Watch during the summer. Otherwise, it’s just some kind of mysticism, when there are no sources for moisture, but it appears.

  • #5

    If the bath is wet, then this is of course not entirely correct, so you need to look at why the ventilation is so improperly arranged and call in specialists to correct this failure.

  • org/Comment”>


    Posted by Dmitri

    View message

    I found myself in such trouble. One outer wall of the bath is constantly wet, and there are no visible sources of moisture near this wall. Neither inside nor outside. What is this?

    Isn’t this wall attached to the steam room? If so, then the cause is condensation. Very hot inside, cool outside. It is necessary to make a thickening of the wall in order to reduce the temperature difference.

  • #7

    It seems to me that the problem is poor ventilation, do you leave the sauna open after use? If not, then it is advisable to do it in such a way that it dries faster. Is there ventilation in the bathhouse?

  • #8

    Posted by Nikolaich

    View message

    I think the problem is poor ventilation, do you leave the sauna open after use? If not, then it is advisable to do it in such a way that it dries faster. Is there ventilation in the bathhouse?

    And what does ventilation have to do with it when it comes to the outer wall, which is already blown by all the winds. Here it is rather necessary to eliminate the cause of the occurrence of moisture, and not to deal with ventilation.

  • org/Comment”>


    Posted by fred

    View message

    and what does ventilation have to do with it, when it comes to the outer wall, which is already blown by all the winds. here it is rather necessary to eliminate the cause of the occurrence of moisture, and not deal with ventilation.

    so what is the cause of moisture? after all, it cannot come from nowhere, if the bath is constantly used, then from the inside the water obviously cannot penetrate, so you need to look for who is watering the wall for the author. 😀

  • #10

    Posted by Emelianov

    View message

    so what is the cause of moisture? after all, it cannot come from nowhere, if the bath is constantly used, then from the inside the water obviously cannot penetrate, so you need to look for who is watering the wall for the author. :d

    Yes, no one floods. It is possible that between the outer wall and the inner wall there are communications for supplying water to the bathhouse and something is leaking there. As an option.

  • #eleven

    How is the water drain from the roof? Is there a rainwater drainage system? It is possible that it simply flows from the roof, and then the wall, if it is not on the sunny side, does not have time to dry.

  • org/Comment”>


    Condensation is most likely, an extra flag is absorbed into the tree, probably – other reasons are hard to find here, but then again, the wall is wet from the outside … If I were you, I would try to trace the pattern.

  • #13

    Posted by Amazing

    View message

    Condensation is most likely, the extra flag is soaked into the wood, probably – other reasons are hard to find here, but then again, the wall is wet from the outside. .. If I were you, I would try to trace the pattern.

    Yes, good advice about the need to trace the pattern. However, this is not difficult to do if you constantly live in a house with a bathhouse. And it’s another matter if the bath is in the country, where you visit from time to time.

  • #14

    Posted by Vasco

    View message

    How is the roof drain arranged? Is there a rainwater drainage system? It is possible that it simply flows from the roof, and then the wall, if it is not on the sunny side, does not have time to dry.

    Yes, it seems like no. The drain from the roof is arranged in the same way as on the other sides, which are quite dry. As for the other opinions, I’ll take a closer look.

  • #15

    Heat well with the doors open a couple of times and let dry. If it does not help a couple of times, drown in the third. The main thing for you is to dry the wall normally at the moment.






Damp wall in the apartment: what to do?

Residents of apartment buildings, especially owners of corner apartments, sometimes face the unpleasant problem of wet walls in winter. Due to the difference in air temperature outside the house and inside the apartment, condensation begins to settle on the walls.

If this issue is not resolved, black mold will gradually appear, and it, in turn, provokes respiratory diseases and is difficult to remove.

Therefore, it is important to correctly identify the cause of excessive moisture condensation and eliminate it.


  • Why does the wall in the apartment get wet?
  • Damp wall in the apartment: what to do?
  • The wall in the apartment gets wet: where to go?

Why does the wall in the apartment get wet?

Several reasons are possible:

  • The outer wall of the house is freezing through. This option applies to those who live in old houses. Builders could save a lot on thermal insulation, relying on the power of central heating. In such houses in winter it is always cold and damp, the walls are very cold.
  • Insufficient waterproofing . This happens, most often, on the lowest or highest floors. Moisture enters either through the roof due to poor quality roofing, or from the basement through the floor. With poor waterproofing, wet spots on the walls do not appear in winter, but in autumn or spring, in the most damp weather. With enough good heating, the wall will have time to dry out.
  • Insufficient ventilation . Despite the fact that there are certain norms according to which the house is designed, the ventilation system may not work well. For the same reason, windows fog up a lot. Problems with air circulation in the apartment are quite common in a variety of types of houses.
  • Recently renovated . The only case when wet walls are, conditionally, normal. During the repair, a large number of materials containing water are used. At the end of it, moisture still remains in the walls, especially if the room was poorly ventilated. Over time, the walls will dry out.

Damp wall in the apartment: what to do?

As we can see, there are not so many reasons for excessive dampness on the walls, the question arises, how to eliminate them?

If walls get wet after repair , then everything is simple here: thoroughly ventilate the room, and in the cold season you need to take care of the warmth. If the batteries don’t help much, install enough heaters.

Problems with ventilation can be both in a separate area of ​​the apartment, and in general. The local option is easily resolved, you need to remove objects that interfere with air circulation. Let’s say moisture accumulates on a small section of the wall behind curtains and furniture. Rearrange furniture, raise curtains, direct a fan or heater to the area.

A common problem with ventilation is solved with an integrated approach: make sure that the ventilation openings inside the apartment work properly, install an exhaust hood in the kitchen, and ventilate more often.

Insufficient waterproofing is a more serious case. There is only one solution here: you need to find the area where the water comes from and properly isolate it. Most often, seams on the outside of the building suffer. This should be entrusted only to specialists. Frequent ventilation in this case is also recommended, although it must be remembered that it will not completely solve the problem.

Freezing of the outside of the house is another option when independent attempts to cope with the misfortune of wet walls may not only not improve, but even worsen the situation. Many, not being able to insulate the wall from the outside of the building, begin to insulate the room from the inside, and often make it even worse. The dew point can shift, on the contrary, closer to the apartment, and all the moisture will collect even more under the insulation, and then drain into a puddle.

It is important to understand here that if you are not a professional builder and industrial climber, your knowledge of wall insulation technology may not be enough, so it is better to trust those who have been working with such a problem for more than one year.

The wall in the apartment gets wet: where to turn?

So, you open windows and vents every two hours, you bought a heater or a heat gun, but the walls are just as wet, and the air, instead of the freshness of alpine meadows, gives a feeling of dampness. What to do? Who to call?

You need to write an application to the management company . Be responsible and be determined to go all the way. Housing offices do not like to solve such problems, but this is their direct responsibility. Talk to your neighbors first, they probably have the same problem.

The application is made in writing in two copies. In it, indicate in detail how long ago the walls began to get wet, in which area, at what time of the year.

Make sure that your application is recorded, leave one option with a note about when it was accepted.

Next, the management company must send a master to you to inspect the apartment. As a result, an act will be drawn up stating that the wall is actually damp, indicating the reasons.