Damp And Timber Surveys Explained: What We Check, How Long It Takes And When You Need One

If you are buying, selling or managing a property and damp is suspected, an intrusive damp and timber survey gives you a clear diagnosis and a plan. This guide sets out exactly what happens on the day, how we test, how long reports take, when a standalone survey is best, what a Level 2 or Level 3 survey covers and why lenders and buyers value independent evidence. We also cover spray foam roof insulation checks, common issues we find and typical remediation ranges so you can make confident decisions.

 What happens during a damp and timber survey?

We start with a structured discussion about your concerns, recent leaks, past repairs and how you use the building. Then we move through each space to build an evidence trail.

Our intrusive methodology typically includes:

• Moisture profiling across walls and floors using both surface and in depth readings to map where moisture enters and how it moves.

• Hygrothermal checks for condensation risk, including temperature, relative humidity and dew point readings, with commentary on lifestyle and ventilation balance.

• Salt analysis in plaster to differentiate rising damp signatures from hygroscopic salts related to historic contamination or chimney flues.

• Targeted opening up where agreed, for example lifting a small section of floor covering, removing a skirting length or drilling discreet test holes in plaster. We make good small openings and photograph everythingfor your record.

• Timber inspection to identify wet rot, dry rot and wood boring insect activity. We assess bearing ends of joists, sill plates, subfloor voids and roof timbers. Borescope access is used where voids are concealed.

• Calcium Carbide Testing (carbide bomb) where subfloor slabs or screeds require a precise in situ moisture content. This is more reliable for floor coverings than meter only assessments.

• Ventilation assessment, covering extract fan flow rates, background ventilators, subfloor air flow to suspended timber floors, and roof void ventilation. We consider the whole moisture pathway, not just a single wall.

Everything is recorded with photographs, measurements and a clear chain of reasoning. We avoid generic prescriptions. You receive a diagnosis that distinguishes rising damp, penetrating damp, plumbing leaks and condensation so that any remedial spend is targeted.

How long will we be on site, and when will you get the report?

Time on site depends on size and complexity:

• Flats and small terraces, typically 1.5 to 2.5 hours.

• Average three bed houses, typically 2.5 to 4 hours.

• Larger or complex properties, including heritage fabric, may take half a day or more.

  
  

Report turnaround is usually within five working days of inspection. Intrusive testing that requires lab analysis or extensive opening up can add time. We confirm the timescale when you book and keep you updated.

This answers two common questions:

• Do surveyors look for damp? Yes. Our damp and timber specialists undertake systematic moisture profiling and timber decay investigations rather than a quick meter scan.

  
  

• How long does it take to get a damp and timber report? Most clients receive the report within five working days, with faster delivery possible by arrangement.

When do you need a standalone damp and timber survey?

Choose a standalone damp and timber survey when:

• A mortgage valuation or RICS Level 2 report has flagged damp or timber risks and you need evidence for negotiation, quotes or lender approval.

• Visible symptoms are localised but persistent, for example recurring salts, crumbling skirtings or bathroom mould despite cleaning.

• Floor coverings, wall finishes or concealed voids require intrusive testing that sits beyond a standard pre purchase survey.

• You need independent diagnostics before committing to works proposed by a contractor.

Does a Level 3 survey check for damp? Yes.

A Level 3 building survey includes a thorough visual assessment of damp indicators and timber risks within accessible areas, with commentary on causes and recommended next steps. However, Level 3 surveys are typically non intrusive. If the Level 3 identifies damp that requires confirmation by opening up or by Calcium Carbide Testing, we will recommend a specialist damp and timber inspection to verify the mechanism and specify exact remedial measures.

If you are choosing between survey levels, our overview of the difference between level 2 and level 3 survey may help you decide which route to take before commissioning targeted testing.

Diagnosing timber decay and what we look for

Timber problems often follow moisture. We check:

• Wet rot, softened fibres with a fibrous fracture, common in chronically damp zones.

• Dry rot, characteristic cuboidal cracking, mycelium or fruiting bodies and a need for moisture control and isolation measures.

• Wood boring beetle, exit holes and frass types linked to species, with moisture content checks to confirm if infestation is active.

We focus on root cause removal before treatment. In many cases, improved ventilation, leak repair and local timber replacement with correct detailing solve the problem without unnecessary chemical saturation.

Typical remedial strategies and cost ranges

Every property is different, but common solutions include:

• Repairing gutters, downpipes and flashings to stop penetrating damp.

• Repointing with breathable mortar and improving ground levels or drainage to reduce splash back and capillary uptake.

• Re-plastering with appropriate breathable systems after salts management. Avoid hard gypsum on damp walls.

• Subfloor ventilation upgrades, clearing blocked air bricks, adding ducts or fans where necessary.

• Installing or upgrading extraction in kitchens and bathrooms with measured flow rates, and adding background ventilation.

• Local joinery repair or replacement to affected timbers, with preservative treatment where justified.

• Floor moisture remediation based on Calcium Carbide Testing results, which may range from drying and ventilation to targeted membrane or slab works.

  
  

Budget guidance is included in our reports where appropriate so you can plan, obtain quotes and if you are buying, renegotiate.

Why independent diagnostics matter to lenders and buyers

Independent surveys separate evidence from sales. Lenders want clarity on cause, extent and durability of a fix, not a generic damp proof course recommendation. Buyers want to understand risk before exchange. Our reports are RICS regulated, they are impartial and they include photographs and clear reasoning. This is why a damp and timber survey mortgage condition will often ask for an independent damp and timber survey rather than a free quote from a remedial company.

If you are seeking a focused service in the North West, our independent damp surveyor team covers Liverpool, Manchester, Cheshire and North Wales.

Specialist spray foam roof insulation checks

Is there a downside to spray foam insulation? Spray foam applied to roof coverings can seal the underside of slates or tiles, reduce ventilation and hide defects. Common issues include trapped moisture, accelerated timber decay and difficulty inspecting the roof. Why do mortgage lenders not like spray foam insulation? Many lenders see spray foam as a valuation and risk problem because it prevents proper inspection and may mask defects. Some require removal before lending, subject to a qualified roof survey and timber assessment.

Our spray foam assessments include:

• Visual and photographic mapping of coverage, thickness and adhesion.

• Ventilation appraisal of the roof void or warm roof build up.

• Timber moisture content and decay checks, including borescope access.

• Reporting for lender or insurer, with remediation options and indicative costs. Remediation may range from partial removal with local timber repairs to full removal and re roofing where coverings or battens are compromised.

You can read more about spray foam insulation and lender positions in our dedicated service pages.

Clear next steps and how to book

• If your valuation or Level 2 report has flagged damp, book a specialist survey to confirm cause and scope before agreeing to any works.

• If you are commissioning a Level 3 survey on an older or altered property, request that we plan for follow on intrusive testing if indicators are present. This keeps momentum and helps you meet transactiondeadlines.

• Keep notes of symptoms over a few days, including when mould appears, when windows condensate and when musty smells are strongest. This context helps our diagnosis.

For advice or to book, call 0151 314 6650, 01244 631614 or 0161 531 5595. You can also email contact@amssurveys.co.uk. We will confirm scope, agree any opening up, arrange access with the agent or vendor and give you a clear reporting timescale.

Summary

A damp and timber survey is a targeted, intrusive investigation that maps moisture paths, tests where needed, and assesses timber health, ventilation and building detailing. Expect 1.5 to 4 hours on site for most homes and a report within five working days. Level 2 and Level 3 surveys do look for damp, but intrusive confirmation is often needed to finalise a specification. Independent diagnostics are valued by lenders and give you confidence to plan works or renegotiate. If spray foam is present, a specialist roof assessment protects both structure and mortgage ability.

Ready to move forward? Book your damp and timber survey today by phone or email. We are here to help you make clear, cost effective decisions.

Note on helpful resources:

1. For broader survey choices, see our guidance on the difference between level 2 and level 3 survey at https://amssurveys.co.uk/home-surveys

2. Learn more about spray foam insulation at https://www.amssurveys.co.uk/spray-foam-roof-surveys

3. If you need a focused diagnostic, start with damp and timber survey at https://amssurveys.co.uk/damp-and-timber