Damp proofing Merseyside — only once rising damp is actually confirmed
A damp-proof course is a genuine fix for a genuine problem: rising damp with a failed or missing DPC. It's the wrong fix for penetrating damp or condensation, and no honest surveyor would recommend one before confirming which you actually have.
What a chemical DPC installation actually involves
Confirmed diagnosis first
Rising damp confirmed by survey — moisture meter readings, salt analysis and visual pattern, following BS 6576 guidance. No DPC work is proposed before this stage.
Salt-contaminated plaster removed
Plaster is typically removed to around a metre from floor level, since ground salts drawn up with the moisture stay in the plaster even after the wall dries.
Chemical DPC injected
A water-repellent cream or fluid is injected at a horizontal line just above ground level, forming a continuous barrier to further capillary rise.
Salt-retardant re-plastering
Specialist re-plastering keeps any residual salts from migrating into the new surface and affecting redecoration.
Drying time before redecoration
Walls typically need several weeks to dry before decorating, using vapour-permeable, non-vinyl products in the first year.
Why "guaranteed for life" isn't the whole story
A DPC only works if nothing bridges it
If external ground level has been raised above the treated line, if debris sits in a wall cavity, or if the injection line was set at the wrong height, moisture can simply route around a technically sound installation. A long guarantee doesn't fix a bridging issue — the specification and the site conditions do. What an unnecessary or wrongly specified damp-proof course actually costs, in money and in collapsed sales, is set out in our guide to the real cost of getting damp wrong.
We won't propose a chemical DPC where a genuine rising damp diagnosis hasn't been made, and we'll flag any bridging risk we find on site — including ones the wall's own history may have created — as part of the survey, not as an afterthought.
Specified to recognised guidance
BS 6576:2005+A1:2012
Code of practice for diagnosing rising damp in walls of buildings and installing chemical damp-proof courses.
PCA Code of Practice
Investigation and Control of Dampness in Buildings (2017, updated 2023) — the Property Care Association's diagnostic and remedial framework.
FODCS Qualified
Federation of Damp Certified Surveyor (FODCS) — City & Guilds Assured and CPD-certified training. Every diagnosis is carried out personally.
Building Regs Part C
Sets functional expectations for resisting moisture in the building fabric — it doesn't prescribe a chemical DPC as a universal answer.
Damp proofing FAQs
Only if rising damp is genuinely confirmed. A lot of "damp" is actually penetrating damp or condensation, which a DPC won't fix. We diagnose first and recommend accordingly.
Typically several weeks depending on wall thickness and conditions, before final redecoration with vapour-permeable products.
Not necessarily. A guarantee doesn't protect against bridging issues like raised external ground or debris in a cavity — the specification and site conditions matter more than the guarantee length on its own.
Salt-contaminated plaster is typically removed to around a metre from floor level and replaced with salt-retardant plaster, since residual ground salts stay in old plaster even once the wall itself has dried.
Yes. If ground level is built up above the damp-proof course — a raised bed, a new patio, a driveway — moisture can bridge straight over it, bypassing the DPC entirely regardless of how well it's working underneath.
A physical DPC is a solid barrier — a slate or plastic membrane — usually built into the wall during construction. A chemical DPC is a cream or fluid injected into the mortar course to create a water-resistant barrier where a physical one is missing, damaged, or bridged.