What is Damp Proofing?

Damp proofing is the process of keeping undesirable moisture out of your home to prevent damp issues. Moisture can enter your home by absorbing upwards or through an external wall surface (normally brick or stone) into the structure and wall plasters beneath. Once inside, it can cause mould growth, damp walls, rot, and structural damage. A damp proof course provides a line of protection around a property, preventing moisture from travelling upwards and into the home.

In buildings, water can move freely and, unless a suitable damp proofing barrier prevents it, moisture will affect many parts of the home. Moisture will eventually become visible on the internal surfaces of a home causing crumbling plaster, damp patches and, possibly, black mould. If this is evident in your home, it is more than likely that the property is not adequately protected by a damp proofing system. It has been widely reported that the presence of damp can impact health and so it is important to ensure proper damp proofing in UK homes.

Causes of Damp

The causes of damp are numerous. There are a wide range of reasons why your home may suffer as a result of water or water vapour. Some common examples of this are:

  • Insufficient protection from rising damp
  • Blocked or leaking guttering
  • Missing or broken roof tiles
  • Penetrating damp through earth-retaining walls
  • Cracked or broken water pipes
  • Crumbling brickwork or mortar
  • Poor ventilation

When water makes its way inside a building, this is called water ingress. Before deploying damp repair solutions and treatments, your water ingress issue should first be fixed to stop any ongoing issues.

A surveyor inspecting a building

Types of Damp

There are three main types of damp; rising damp, penetrating damp and condensation. Your damp proofing specialists will be able to identify the type of damp affecting your home so that it can be treated properly.

Rising Damp

Rising damp occurs when water from the ground is absorbed into your walls through capillary action. As the water spreads through building materials, your home may additionally develop timber issues such as wet rot or woodworm.

The most obvious signs of rising damp are:

  • Flaking plaster and paint
  • Salt deposits on wall surfaces
  • Loosening wallpaper
  • Damp stains on walls 

Most homes should have a damp proof course fitted to stop rising damp. However, this may not be present or may otherwise be defective in older homes. 

If you believe that you have rising damp, you should contact a damp proofing specialist immediately.

Penetrating Damp

Penetrating damp is the process of water from outside your home penetrating and causing a problem inside. The most common causes of penetrating damp are leaking gutters, plumbing issues, water from earth-retaining walls, poorly fitted windows and building defects. 

The most obvious signs of penetrating damp are:

  • Cracks in mortar joints and surfaces
  • Vegetation growth on external walls
  • Plaster blistering 

Penetrating damp can compromise a property’s insulation, weaken floors, create structural instability and cause severe damage to your home’s interior. It should be treated and corrected as soon as it’s spotted.


Condensation, the most common cause of damp, forms when humid air comes into contact with cold surfaces such as cold walls or windows. The most typical causes of condensation are poor ventilation, poorly heated homes and high humidity (due to cooking, bathing and washing for example)

The most obvious signs of condensation are:

  • Black mould
  • Wet windows (internally)
  • Water collecting on window sills

Condensation can be resolved by ventilating and insulating your home properly. Only a professional company can design an effective damp proofing solution to remedy a condensation issue.

I Found Damp, What Should I Do?

Damp can cause many issues in your home if not treated properly and quickly. Damp and mould can cause cracks in bricks and mortar, damage to internal walls as well allow wet rot to form in timber structures. In addition to structural and aesthetic damage, living in a damp and humid environment can cause serious health issues such as breathing issues, asthma, and fevers.

For homes suffering with such issues, remedial damp treatments as well as preventative damp solutions are vital. If you find signs of damp in your home, get in touch immediately.

Our team of experts specialise in the design and installation of specialist damp proofing systems, which will keep your home free of damp. Where walls are affected by rising damp, our technicians inject chemical damp proofing courses, which provide a continuous and lasting barrier against any future water ingress.

Damp Treatments we use

Allerton ALL DAMP DPC Gun
ALLDAMP Chemical Damp Proof Course

A retrofit chemical damp proof course, exclusive to the ALLDAMP product range. When installed by our qualified damp contractors, the chemical adds a water resistant quality to the mortar between a property’s brickwork, preventing rising damp occurring in future.

With the ALLDAMP Chemical Damp Proof Course, homeowners can rest assured that their property is protected against rising damp now and for the long-term. This is a product which, when installed by Allerton, can be guaranteed to last for 20 Years.

ALLDAMP Render Additive

 A specially-formulated render additive which acts as a water inhibitor and plasticiser. When carrying out plastering inside homes, our staff use ALLDAMP Render Additive, turning their plasterwork into a damp proof barrier to future water ingress. 

ALLDAMP Render Additive is used in most Allerton repair projects. With this system, homeowners can redecorate and furnish with the confidence that damp will not return in future.

ALLDAMP Damp Proofing Membrane

A specially-designed wall covering, which creates a damp proof surface over which plaster can be applied. The ALLDAMP damp proofing membrane creates a damp proof barrier and cavity between the existing brickwork and wall surface, preventing future damp penetration.

ALLDAMP Damp Proofing Membrane is an incredibly versatile product which is suitable for use above and below ground. It is our go-to product for carrying out basement waterproofing projects.


How does a chemical stop damp?

The chemical which our technicians use is injected in a continuous line near the base of a wall affected by rising damp. When the chemical cures, it acts as a waterproof barrier which prevents any additional water rising past it and into the interior of your home.

Why use a chemical rather than a membrane?

Chemical damp proof courses are a cost-effective method of treating rising damp as their injection does not normally require the disturbance or removal of brickwork like would be necessary for physical damp proof courses. However, in most cases, the interior wall plaster which has been affected by damp will need replacement, irrespective of the kind of damp proof course that is used.

I have damp, why does the wall plaster need to be removed?

If you’ve found damp in your home, you might have noticed a white sediment deposited on the surface of the affected walls; this is salt. Any damp that makes its way into a property carries with it a range of minerals (including salts) and deposits these in the surface of the wall as it evaporates. This is a problem for two reasons:

  1. It leaves a permanent stain on the wall
  2. The salts which are deposited are hygroscopic. Meaning, even when the source of the damp that deposited them has been cured, they will continue to attract moisture from the internal air of the property, leaving the wall appearing permanently damp. Where these salts are present, the wall plasters must be replaced. As part of their work, our technicians commonly remove salt contaminated wall plaster and replace it with specialist salt retardant plasters to prevent the problem reoccurring.

Find Your Local Damp Proofing Specialist

Contact Us To Book A Survey

Whatever your needs, a member of our Customer Care Team will be happy to hear from you. They are trained in all areas of our work from damp proofing to cellar conversions and will aim to help you as far as possible at the initial stage. They’re friendly, approachable and they always have time to discuss your property needs.


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