We have come a long way since the old days of bitumen and slate Damp Proof Courses (DPC), with these and Damp Proof Membrane (DPM) now made from much more effective materials like polyethene and visqueen so they last longer and provide greater protection.

Damp proofing is absolutely essential to every build, affecting not only the quality and durability of the final result, but energy efficiency, safety, and the health and wellbeing of the people living or working there. Choosing the right materials is always important, but with damp proofing, it is even more so.

Some contractors have a personal preference for DPM or DPC, and there are a number of pros and cons for each. A lot of this depends on the specific building and circumstances, but often, your best bet is a combination of the two. 

What is damp proof course (DPC)?

Damp Proof Course is a barrier designed specifically to protect walls against rising damp. During construction, DPC is now always placed between courses of brickwork, to stop moisture that seeps upwards from the ground. 

Advantages and disadvantages of Damp Proof Courses (DPC)

DPC is well-known as an effective guard against rising damp. It provides some highly specialised benefits that can’t be beaten:

• It’s generally the best available protection against rising damp.
• It prevents health issues and protects the stability of the structure.
• Helps ensure that a project meets government regulations.
• Improves the lifespan and appearance of skirting boards, and of paint and wallpaper, especially on the lower areas of walls.
• Prevents wet rot and dry rot associated with rising damp.

A major disadvantage of DPC is that it can only protect walls – not floors or other parts of the building – and only against rising damp. You will still need DPM to prevent damage from condensation and water ingress.

DPC is also available in an injectable/chemical form. This is a popular and effective way to add damp proofing to a home, but bear in mind that:

• If you’re adding DPC to an existing building, holes will need to be drilled into the walls.
• Cracks can develop when DPC is installed.
• It adds weight to the entire structure.
• Patches or discolouration can appear on the walls.
• It can lead to levelling problems.

What is Damp Proof Membrane (DPM)?

Damp Proof Membrane comes in large sheets of polythene or similar, which can be used throughout a building to prevent water/vapour from getting through walls and timber or moving between different parts of the building. It is often also used to coat the underside or inside of flooring and other surfaces.

DPM is usually supplied as a wider sheet, and we stock a range of sizes to suit all your construction requirements.

Advantages and disadvantages of damp proof membrane (DPM)

The one disadvantage that applies to both DPM and DPC is that while these barriers are very effective, none of them is 100% waterproof, so over time some moisture can start to get through. They should last for decades though, as long as they are good quality and correctly installed.

We can list many, many advantages of DPM:

• Damp Proof Membrane is extremely versatile – it can be used in various parts of a building.
• For optimum damp proofing, DPM can be used alongside DPC. In some cases, it should also connect with or overlap DPC to provide full protection.
• It is designed to cover wider surface areas.
• DPM prevents water from moving through concrete and other materials, stopping it before it reaches the surfaces of walls, flooring, or masonry.
• If damp does occur in one wall/area, DPM stops it from spreading.
• It also prevents salt contamination from spreading.
• DPM provides damp proofing under new slabs, decking, and other home additions.
• It is also very handy for garden and landscaping projects that need to be water resistant.
• It should last at least 30 years, under the right conditions.

Choosing between DPM and DPC doesn’t have to be a tough decision, and most buildings will benefit from a combination of the two. With our range of quality damp proofing products and budget-friendly pricing, it’s also very cost-effective to use the best of both worlds, so you can assure clients that you are successfully following building regulations and providing the best results every time.

Have a question about damp proofing products or what’s most suitable for a specific project? Give us a call on 01604 581444