Damp Proofing and Timber Treatments: Essential Records to Keep

Damp and timber decay are among the most common issues flagged during UK property surveys. Whether you are dealing with rising damp, penetrating damp, wood-boring beetle infestations, or wet and dry rot, remedial work is rarely cheap. More importantly, remedial work is largely invisible once walls are replastered and floorboards are relaid.

Because future buyers, mortgage lenders, and building surveyors cannot see chemical damp-proof courses or timber preservative treatments once the job is finished, they rely entirely on documentation. Without proper records, previous treatments carry little weight during a property transaction, potentially leading to renegotiations, delays, or expensive repeat surveys.

The initial survey report and diagnostic specification

Every professional damp or timber treatment should begin with a thorough inspection by a qualified specialist. The resulting report is a crucial document to retain, as it establishes the baseline condition of the building before any work took place.

Your survey documentation should clearly state the root cause of the moisture or fungal issue, rather than just treating the visible symptom. Keep the following diagnostic records safe:

• The specialist surveyor's inspection report, including moisture readings and visual observations
• Floor plans or sketches indicating exactly where damp or timber decay was identified
• The proposed scope of works and treatment specification (such as chemical injection, physical membrane installation, or fungicidal timber treatment)
• Notes on associated external defects that required fixing, such as leaking gutters, breached ground levels, or defective pointing

Contractor certificates and treatment details

Once works are complete, the contractor must supply paperwork detailing what was done, the products used, and where they were applied. For damp-proof courses (DPC), this includes details of the chemical injection fluid, silicone cream, or cavity membrane system installed.

For timber treatments addressing woodworm or rot, the paperwork should outline the chemicals applied to joists, wall plates, or rafters, as well as the extent of any timber replacement. Ensure you retain the detailed final invoice showing payment in full, as most guarantees are conditional on the account being settled.

Understanding contractor and insurance-backed guarantees

Damp proofing and timber treatments often come with long warranties, typically lasting between 10 and 30 years. However, a written guarantee on a contractor's letterhead is only as strong as the business providing it. If that company ceases trading, their company guarantee becomes worthless.

To protect against this, reputable remedial companies offer an Insurance-Backed Guarantee (IBG). An IBG is an insurance policy that honours the terms of the original contractor's guarantee if the contractor goes out of business. To ensure your guarantee is recognised by future buyers and mortgage lenders, you must keep the original company warranty alongside the specific IBG policy schedule and terms.

Check whether the guarantee is automatically transferable to future owners of the property, or if a formal transfer process and administration fee are required at the time of sale. Storing these conditions clearly prevents complications years down the line.

Replastering, insulation, and building standards

Treating damp often involves hacking off contaminated plaster back to the bare substrate and replastering with salt-retardant backing plasters or installing a studded mesh membrane. The replastering specification is just as critical as the chemical injection itself, because hygroscopic ground salts left in the wall can continue to draw moisture from the room if standard gypsum plaster is used.

If substantial areas of external wall insulation or internal lining were replaced, check whether Building Regulations were applicable to your project. Retain copies of the technical data sheets for any specialised plastering systems, waterproof renders, or membranes used.

Photographs and ongoing maintenance records

High-resolution photographs taken before, during, and after remedial work provide undeniable proof of what was done. Photographs of exposed joist ends, injection hole spacing, and membrane installation provide clarity that written reports alone cannot match.

Using an independent record-keeping platform like Project Passport allows you to link these progress photographs directly to the survey reports, technical specifications, and guarantee schedules. Storing this evidence centrally ensures you have an organised history ready whenever a surveyor visits or a future purchaser asks for clarification.

Finally, remember that damp management relies on ongoing building care. Keep records of routine maintenance that protects your damp proofing, such as regular gutter clearing, maintaining sub-floor air vents, and keeping external ground levels at least 150mm below the damp-proof course. By holding all these documents in Project Passport, you maintain a clear, verifiable record of your home's structural health.