Damp Proofing Installation Principles
What it looks like
Breaches, incorrect lapping, or punctures in DPCs/DPMs lead to capillary rise or lateral moisture penetration, causing dampness.
Why it happens
Damp proofing must be installed to create a continuous physical barrier against moisture ingress, directing water away from the building. This involves the correct positioning of damp-proof courses (DPCs) and damp-proof membranes (DPMs), including at junctions between different building components and systems. Appropriate tapes and sealants should be used in conjunction with the main damp proofing materials, following manufacturer's recommendations, but should not be solely relied upon for the barrier.
What it costs if it is missed
Damp proofing must be installed to create a continuous physical barrier against moisture ingress, directing water away from the building. This involves the correct positioning of damp-proof courses (DPCs) and damp-proof membranes (DPMs), including at junctions between different building components and systems. Appropriate tapes and sealants should be used in conjunction with the main damp proofing materials, following manufacturer's recommendations, but should not be solely relied upon for the barrier.
How to inspect for it
Check that DPCs and DPMs are correctly installed, lapped, and form a continuous barrier, with appropriate sealing at all junctions.
How to prevent it
Damp proofing must be installed to create a continuous physical barrier against moisture ingress, directing water away from the building. This involves the correct positioning of damp-proof courses (DPCs) and damp-proof membranes (DPMs), including at junctions between different building components and systems. Appropriate tapes and sealants should be used in conjunction with the main damp proofing materials, following manufacturer's recommendations, but should not be solely relied upon for the barrier.
Basis in regulation
BS 8102
Read the source
Last updated 23 August 2026. This is our editorial summary of publicly available regulation and site practice, not building control approval or a warranty determination.