Applying a damp proof membrane to an internal wall is an excellent solution for damp issues in many situations. A membrane can be applied to a wall after a new damp proof course had been inserted or injected, and a DPM (Damp Proof Membrane) is an effective way of isolating damp walls and those that have salts and other contaminants. Your choice of damp proof membrane should be determined by the extent of the damp and contamination and the finish you require. DIY DPM kits are widely available and specific installation instructions will vary accordingly, and should always be followed closely. However, the general principles of how to apply a damp proof membrane are largely the same. So, here is a general damp proof membrane installation guide.

1. A typical DIY Damp Proofing Kit will include a roll of meshed membrane:

It will also include plaster plugs and sealing washers, a masonry drill bit, and often a mastic sealant. This is to apply to the plugs before the membrane is fixed.

2. Remove any loose, crumbling or flaking plaster from the substrate. The surface should be as clean and flat as possible.
3. Using a knife or sharp scissors, cut the membrane sheet to size.
4. Place the membrane to the wall and neatly fold around any corners. The crucial thing is that any wrinkles and creases are removed.
5. Fix the membrane to the wall by drilling holes into the wall. It is best to start from the centre and works outwards, at 25cm intervals. Insert the fixing plug (and apply mastic, if using) and the sealing washer. Flatten out any creases before hammering each plug securely into place.

This video shows the process:

You can see a speeded up version of someone installing membrane to an entire room:

6. Once all the plugs have been fixed to the wall, you are ready to apply your plasterboard finish to the wall. There are four main ways of doing this:

• Timber battens that are fixed horizontally
• Metal framework systems
• Direct plaster finish
• Dot and dab

Each of these methods work well. The dot and dab method is the simplest and quickest. Follow the advice and instructions given with the particular DIY Damp Proof Membrane Kit that you buy.

The video below shows each of these four methods in action.

Once the plasterboard is in place, you are ready to plaster and apply your decorated finish.

So, there you have it – your complete damp proof membrane installation guide. As we said above, there will be minor differences between the exact methods that you should use. However, these should be clearly explained in the kit you choose and in general the installation process is very similar, as detailed above.

Applying a damp proof membrane for walls can be an excellent solution for damp problems in the home. A damp proofing membrane has several advantages. Firstly, it is a relatively cheap and easy process to install one – DIY kits are widely available and you certainly don’t need to consider yourself a DIY expert to attempt the work yourself. Secondly, damp proof membranes are suitable solutions for a variety of cases of damp (more of that later). And, thirdly, damp proof membranes offer long lasting protection against damp, particularly issues such as condensation and black mould spots.

What are the main uses for a damp proof membrane?

Damp proof membranes are best suited for properties that have just had a new damp proof course inserted. In virtually all cases of damp (except where structural damage has occurred), remedial treatment such as a new DPC will be sufficient. However, because of the effects of damp, surfaces may have deteriorated. This is where a damp proof membrane for walls really comes into its own, as it can provide a key for that deteriorating surface.

Damp proof membranes are also useful to isolate already damp walls or those contaminated with salt.

What is a damp proof membrane and how do they work?

Damp proof wall membranes are essentially a plastic sheet. Different materials are used depending on the intended application, the extent of the damp and the finish that is required on the wall – always seek advice about what might be the most appropriate membrane to use.

The thickness of a damp proof membrane is typically 0.5mm to 1mm with stud sizes ranging from 1mm to as much as 8mm. Some membranes use a dry lining system as a finish. Others have a mesh welded in to allow for rendering and plastering after application.

The cavity, or air gap, that a damp proofing membrane has creates up to 10 litres of space in between the membrane and the wall.

A damp proof membrane for walls has a long life expectancy (typically over 30 years) and is very strong and flexible too. As they can compensate for any structural movement over time, they provide longevity and peace of mind.

The membrane provides a physical barrier between the existing damp wall and the new finish. It also prevents any vapour and moisture, along with salts and contaminants, from impacting on the internal finish of the wall. They significantly prolong the life of the new internal finish.

Is a damp proof membrane the solution?

Certainly, if used in conjunction with a new damp proof course, a damp proof membrane can be an excellent solution. This is because it adds an extra (and long lasting) protection from damp which is a fantastic way of treating surfaces that have been damaged by damp.

Applying a damp proof membrane to an internal wall is also cost-effective and as they can be installed with very little, if any, surface preparation, it’s no surprise that it is a popular solution.

For DIY enthusiasts, it’s a project that most will feel confident enough to take on. The installation really only requires cutting the membrane to the correct size, placing it to the wall and neatly folding the membrane around the corners.

Then all that is required is drilling and fixing the membrane to ensure a tight fit and applying the wall finish to the membrane.

Of course, if the membrane isn’t of the appropriate type or thickness and isn’t applied with a well-fitting and tight fit, then you run the risk of it failing. Therefore, it’s never a bad idea to seek, at the very least, professional advice if you are considering the solution of a damp proof membrane for walls.