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Everything You Need to Know About Getting a Damp Proof Course for Your Building

If you have a building that is suffering from extensive damp and all the issues associated with it, a DPC or damp-proof course treatment may be your best option for getting rid of the damp.

But what exactly is a DPC treatment? And how do you go about getting one for your building? Keep reading to find out.

What is a Damp Proof Course?

A damp proof course is basically a moisture-resistant barrier applied to the foundation, walls and floors of a building to prevent water or moisture from getting in. A DPC treatment is aimed at stopping water or moisture from rising up the walls from the ground (rising damp).

How to Know if You Need a Damp Proof Course?

You should consider the following when deciding if getting a damp-proof course is what you need;

The Age of Your Property- Older houses don’t usually come with an installed damp-proof course, and even if they do, it is usually compromised and not very functional. If you find yourself with an older house that has a damp problem, a new DPC is your best bet at keeping the moisture at bay.

Most newer buildings are required to have damp-proof courses, so if you find yourself with a damp issue, it is likely that the damp-proof course is faulty or incorrectly installed.

Signs of Rising Damp- If your building has visible signs of rising damp (tide marks on the walls, discolouration, a damp smell, peeling paint, plaster or wallpaper), then installing a DPC may be in order. If there is a damp proof course already in place, the rising damp could be a sign that it is no longer effective and needs to be replaced.

Professional Opinion- Regardless of whether or not you’re sure of the extent of your building’s damp problem, hiring a damp specialist to carry out a survey is always recommended. Their trained eye can easily spot the signs that you may have missed. They will also be able to determine the underlying cause of the damp and ensure that you get the best DPC treatment for your property.

Materials Used for Damp Proof Course

The materials that are commonly used to prevent dampness can be classified into three categories which are flexible (plastic sheeting, bitumen felts), semi-rigid (mastic asphalt), and rigid (cement concrete, slate, first-class bricks and stones).

The materials used for a DPC should also possess the following properties;

  • Imperviousness to moisture.
  • Durability, strength and ability to withstand live and dead loads without damage.
  • Dimensional stability.
  • Absence of deliquescent salts like nitrates, sulphates and chlorides.

Selection of Materials for a Damp Proof Course

When it comes to selecting a material to function as an effective damp proof course, careful consideration is required. Factors like the nature of the building, the situation where the DPC is to be provided, climate and even atmospheric conditions need to be considered.

Types of Damp Proof Course

Damp-Proof injection

This is also known as chemical damp proofing. It involves drilling 10mm holes (usually 150mm above the external ground) and injecting a cream or liquid into the wall to create a layer that is water-repellent. This water-repellent layer can effectively prevent moisture from rising above the DPC and into the walls. When done correctly, a damp-proof injection is very long-lasting and great for thick walls, however, it can be messy and time-consuming. To have this work done correctly, search on the internet for something like ‘damp specialists London’.

Membrane Damp Proof Course

Here, a plastic membrane material is installed underneath the concrete slab to prevent it from becoming damp. The membranes are quite flexible, so dealing with structural movement won’t be an issue. When done right, a membrane damp proof course can last up to 30 years.

Mortar Injection Damp Proof Course

This is similar to a damp proof injection, except that a chemically-enhanced mortar is used instead of a liquid or cream. This type of DPC can be used for walls that have rubble or voids within their structure. The only downside is that this method of damp proofing can be unsightly.

Cavity Wall Damp Proof Course

A cavity wall prevents damp by separating the inner walls from the external walls. The barrier formed prevents damp from leaking through the external walls and into the internal walls. A cavity wall also offers additional benefits such as; sound and thermal insulation.


Damp is a serious issue that can compromise the structural integrity of your building if left untreated. Thankfully, a damp proof course can effectively treat damp and ward off future damp issues. There are different types of damp proof courses, including different materials that can be used. Hopefully, this article has been helpful in telling you what you need to know about getting a DPC for your building.