Damp Course & Membrane

Frequently Asked Questions – Damp Proof Course & Membrane

What's the difference between DPC and DPM?

A damp proof course (DPC) is installed within walls to help prevent moisture rising through brickwork or blockwork. A damp proof membrane (DPM) is generally a larger sheet membrane used within ground floor construction to help prevent moisture passing from the ground into the building.

What does DPC stand for?

DPC stands for Damp Proof Course. It forms a moisture-resistant barrier within the construction of a wall and is an important part of protecting buildings against rising damp.

What does DPM stand for?

DPM stands for Damp Proof Membrane. It's typically installed as part of a ground floor construction to provide a barrier between the ground and the floor above, helping prevent ground moisture entering the building.

What width DPC do I need?

The correct DPC width depends on the thickness and construction of the wall and the particular application. County Building Supplies stocks DPC in a range of widths, including 100mm, 150mm, 225mm, 300mm and 450mm options. Always use the width specified for your wall construction and project.

What's the difference between polythene DPC and IKO Hyload DPC?

Both are designed to provide a damp proof barrier within wall construction, but they're manufactured from different materials and have different product specifications. The most suitable option depends on the application and project requirements. Always check the manufacturer's technical information before selecting a DPC.

What is 1200 gauge DPM used for?

1200 gauge polythene damp proof membrane is commonly used within ground floor construction to help prevent moisture from the ground passing into the building. County Building Supplies stocks 1200 gauge DPM in large sheets suitable for covering floor areas.

Can DPM sheets be joined together?

Yes. Where more than one sheet is required, damp proof membranes can be joined to create a continuous barrier. The required overlap, sealing method and jointing products depend on the membrane and installation specification, so always follow the manufacturer's instructions.

Does a DPM need to connect to the DPC?

In many building designs, the floor damp proof membrane and wall damp proof course are detailed so that they create a continuous barrier against moisture. The exact arrangement depends on the construction design, so installation should follow the project drawings and relevant Building Regulations.

Can I cut DPC to size?

DPC rolls can be cut to the required length during installation. However, the width should be appropriate for the wall construction rather than simply cutting down a wider product without considering the installation requirements.

What happens if a damp proof membrane gets damaged?

Punctures or tears can compromise the continuity of a damp proof membrane. Damage should be repaired using an appropriate method and compatible materials in accordance with the membrane manufacturer's instructions before the floor construction continues.

Do you sell DPC and DPM in different sizes?

Yes. County Building Supplies stocks damp proof course rolls in several widths, including IKO Hyload Trade DPC and polythene DPC, as well as 1200 gauge polythene damp proof membrane. Product availability may vary, so check online or contact your local branch if you require a particular size or quantity.

Do you deliver damp proof course and membrane?

Yes. We offer local delivery for damp proofing products and other building materials across our trading area. Delivery options and product availability may vary depending on your location and order size, so contact your nearest County Building Supplies branch for more information.