Penetrating Damp

Penetrating Damp - what is it and how to fix it

This page will give you an outline of what penetrating damp is, how it differs from other types of damp, how to identify it and how it can be fixed.

Damp Genius are experts at solving penetrating damp problems using cutting edge technology such as ProPERLA exterior coatings. We offer a complete service including repointing, render repairs and waterproof coatings.

Read on to find out more about this problem and how it affects buildings.

penetrating damp on wall how to fix it
Penetrating damp often causes salt damage and peeling paint

What is Penetrating Damp?

As you might expect, penetrating damp, is moisture which enters a building from the outside directly through a wall. This type of damp often shows up as dark patches on the walls, occasionally with some white salts present, and often the patches are in a quite random pattern. Sometimes you may notice the patches get worse when it rains.

How to Identify Penetrating Damp

All types of damp in buildings have different patterns and key indicators which can be used to identify if you have penetrating damp. The other main types of damp are rising damp and condensation (or airborne moisture). To help you identify which type of damp you have download our easy to use flow chart guide at the bottom of the page.

An easy way to identify penetrating damp is to think about the location of the problem. For example, if the damp patches are on the first floor or at ceiling level on the ground floor then they cannot be rising damp.

If the damp patches on the first floor have mould present then they are most likely to be caused by condensation as the mould loves the clean, pure, water formed by condensation.

Penetrating damp will generally not have any black mould on it but may have white salt deposits showing which are sometimes confused as a type of mould.  These salts, known as efflorescence, indicate that water has been running through the structure. 

An area to be careful of when diagnosing the problems is around window frames. These can very often be wet in the mornings due to condensation forming overnight, particularly in bedrooms, but this is not penetrating damp. If this is a problem for you then check out our info on PIV units which can eliminate this issue.

Common Causes of Penetrating Damp

There are a whole range of water ingress issues which can lead to penetrating damp problems, some of the more common ones we encounter are listed below.

Damaged Render

This is often easy to spot as the walls will have bulges on the outside or even obvious crack lines on the render. Tapping the wall with a small hammer will find the hollow cavities. These cavities fill with water which then gradually soaks into the wall.

crack in render causes penetrating damp
Cracks in external render trap rainwater against the wall
Porous Bricks or Stone

Some types of bricks and stone are more porous than others but all of them will absorb moisture over time. This defects can be hard to spot and if you are having problems then it is usually best to call in a professional.

Damaged Pointing

Pointing should last at least 50 years on most buildings but it does still fail leading to penetrating damp problems. This type of problem is usually easy to spot by the deep gaps between the bricks or stone.

Flaking Damaged External Paint

Often overlooked as a merely cosmetic issue, we find that flaking paint is common cause of penetrating damp. Water gets trapped behind the paint where it can seep through the wall to the inside of your home.

Broken or Overflowing Guttering

This one is dead easy to spot but unfortunately so often ignored by property owners. Fixing leaking and overflowing gutters is essential to keeping any building dry and safe for years to come.

blocked gutters cause penetrating damp
Grass growing out of a gutter is a common cause of penetrating damp

How to Fix Penetrating Damp

As you can see there are numerous common causes of penetrating damp which can affect buildings. Some of the causes have an easy fix, such as a blocked gutter, others such as cracked render or damaged pointing are likely to need a professional to get involved. 

Damp Genius are able to fix and repair cracked render, defective pointing and then protect your home using advanced waterproof wall coatings which will prevent penetrating damp happening again. 

Another important consideration is that once the external cause of penetrating damp is fixed it is often necessary to repair the plastering inside the house. Salt damage tends to ruin plaster for the long term and even once water has stopped coming in to the building the plaster will never quite recover. As damp specialists we are well qualified to undertake the internal work as well to give you a complete solution. 

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Contact Us

You can contact us using the form below or any of the contacts at the top of this page. We will be pleased to discuss your damp issue and then, if needed, we will arrange a suitable time to visit to prepare a quote or carry out a survey. 

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