Damp proof membrane installed on walls in property

What is a Damp Proof Membrane and How Does It Work?

What exactly is a Damp Proof Membrane?

A damp proof membrane (DPM) is a type of membrane material is used to prevent dampness from occurring through capillary action. It is often used underneath a concrete floor to stop it from gaining moisture.

A damp proof membrane can also be placed above the concrete in the walls in conjunction with a damp proof course (DPC). DPM is one of the most reliable damp proofing solutions for getting rid of damp from your property.

How Does A Damp Proof Membrane Work?

Damp proof membranes are made from plastic which means that they can protect against moisture. The surface of the damp membrane is formed into a stud formation which creates an air gap allowing the water to evaporate while leaving the wall unobstructed.

Real care must be taken when installing it to ensure that there are tears or holes are in the plastic membrane sheet as this would allow the penetration of moisture. If this were to happen this would mean this form of damp protection would lose all effectiveness.

The damp proof membrane material should be in accordance with the British Standards. The building regulations by the Government propose that the sheet of polyethylene should be 1200 gauge.

Using a sheet that doesn’t meet building regulations could mean your property may be affected by water ingress in the future, which would mean expensive costs in the future.

Therefore, it is important to contact a damp proofing professional, who has professional experience in the damp-proofing industry to ensure that it does not happen.

The Damp Proofing Membrane Installation Process

Surveyor and membrane

One of the reasons why having a damp proof membrane is often preferred is that it is not only easy to install but also flexible. With DPM being flexible it can cope with structural movement which means it is longer lasting and less chance of failure.

The process for how a damp proofing specialist typically installs a damp proof membrane is shown below:

  1. The source of the damp problem will have been identified and rectified by the surveyor and technician. The plaster will then be removed from the wall and original masonry will be rendered back.
  2. The damp proof membrane will be cut to the size of the wall.
  3. The technician will carefully place the membrane onto the wall.
  4. The damp proof membrane will be drilled to ensure that it is securely placed.
  5. Special membrane fixed plugs will then be put in place to ensure that the plastic membrane is fixed in place whilst not allowing moisture to pass.
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Damp Proof Membrane Working with A Damp-Proof Course

To ensure that you have full protection from rising damp, a damp membrane will be placed onto the Damp Proof Course (or DPC). It is normal if the technician when installing the DPM to overlap the damp proof course. The damp proof course is placed within the brickwork to stop any damp rising up from the ground through capillary action.

The height of the DPC is normally a minimum of 150 mm. The plastic membrane will then be folded inside of the wall which will overlap the damp course, therefore providing a more efficient barrier against moisture.

Problems That Will Occur Without Having a DPM In Place

There are 3 types of damp problems that can occur in your property – these are rising damp, penetrating damp and condensation. If not treated within a sufficient amount of time these can cause serious damage to the infrastructure of the building.

Having damp in buildings can cause damage to your property with the following issues:

  • Mould growth
  • Damp Patches
  • Wood rotting fungal decay
  • Wallpaper will deteriorate and be discoloured
  • Skirting boards will become broken and brittle

Dampness on an internal wall

There are other factors to consider as well such as the health risks of living in a property affected by damp. Mould growth can cause asthma and other respiratory issues to the young and older population.

Having damp walls can also mean that your property is less energy efficient meaning the costs for keeping the building warmer will increase.

Need Further Information?

We hope this article has provided you with more understanding of what a damp proof membrane is and why it is necessary for protection against dampness.

If you would like further information about DPM’s or would like one installed at your property, then contact our team at Timberwise would be happy to help.