Damp Survey — What Does It Actually Involve?

Most homeowners have no idea what a damp survey actually involves before the surveyor turns up. That's normal — you don't need one until you do, and once you do, the unknown can feel uncomfortable. Are they going to drill holes in your walls? Will it take the whole day? Will you be told you need £6,000 of treatment by lunchtime?

This guide walks through exactly what a damp survey is, what gets checked, what tools we use, how long it takes, what you'll be asked, and what you'll get in writing. If you'd rather skip ahead and book one, take our 2-minute damp self-check and we'll send a surveyor.

The 30-second TL;DR

• 30-45 minutes on site for a typical room or two. Whole-house or basement surveys take 60-90 minutes.
• No drilling, no destruction. Modern damp surveys are largely non-invasive — moisture meters, infrared, visual inspection, hygrometer readings.
• Free with us — no charge for the visit or the written report. The fixed-price quote that follows is yours to take or leave.
• Written report within 24-48 hours — your diagnosis in plain English with photos, plus options and prices.
• No same-day pressure. Read it, sleep on it, get a second opinion if you want. We're not selling double glazing.

What the surveyor brings

A typical damp survey kit for our team:

• Electronic moisture meter — the small handheld unit with two pins. Reads surface and near-surface moisture in masonry and plaster.
• Calcium-carbide meter (for definitive readings) — used when the electronic meter shows ambiguous results. Takes a small sample of plaster and gives a direct moisture-content percentage.
• Infrared thermometer or thermal imager — finds cold spots and hidden voids. Useful for diagnosing condensation patterns and locating thermal bridges.
• Hygrometer — measures relative humidity (RH) and air temperature in the room. Gives the dew-point context that condensation diagnosis needs.
• Boroscope — small flexible camera for inspecting cavity walls or under floorboards without removing them.
• Camera + measuring tape — for the report. Every defect we record gets a photo and a location.

Nothing in that kit is invasive. The calcium-carbide test takes a fingernail-sized scrape of plaster from a discreet spot, and that's it. We don't lift floors, drill walls, or strip skirting boards on the survey itself — that comes later if you book treatment.

The 8 things a surveyor actually checks

1. External walls and ground levels

The surveyor walks the perimeter first. They're looking for: ground level above the DPC (a classic cause of rising damp); render damage, cracks or missing pointing; defective gutters, downpipes or drains; vegetation growing against walls; flowerbeds, paths or driveways higher than the airbricks; render or paint bridging the DPC.

This is often where the diagnosis is solved. A surveyor who skips the outside is missing 60% of the picture.

2. Internal walls — low and high

Inside, every affected wall gets read at three heights: skirting level (rising damp lives here), waist level (penetrating damp territory), and ceiling level (condensation belt). The pattern of moisture readings tells the story — rising damp shows a clean horizontal "tide mark" with dry readings above, condensation shows surface-only readings on cold spots, penetrating damp shows a localised wet zone next to its source.

If you're unclear on the difference, our condensation vs rising damp guide walks through how the patterns differ.

3. Floor and skirting levels

Skirting boards are a tell. Crumbling at the back, deteriorated paintwork, soft spongy timber — these point to either rising damp behind them or a leak under the floor. A surveyor will lift a small access point if needed (with your permission) but will more often diagnose from external evidence.

4. DPC condition

The damp-proof course (DPC) is the horizontal barrier in your masonry that stops ground moisture rising. On Victorian and older properties it's often slate; on inter-war and post-war homes it's bitumen felt; on modern homes it's a polythene strip. The surveyor checks: does it exist; is it visible; is it bridged by external render, paint or ground level; is there evidence of failure (a bulging or cracked line two courses above ground level).

5. Ventilation routes

Trickle vents in windows. Airbricks at floor level. Extractor fans in bathrooms and kitchens. Loft venting. If the property has been retrofitted with double glazing, insulation and a new boiler — but the original ventilation routes are blocked or absent — condensation is almost guaranteed. We see this constantly in 1930s semis where the airbricks have been bricked over during a render job.

6. Moisture meter readings at multiple depths

An electronic moisture meter in pin-mode reads ~1cm into the surface; in scan-mode it reads the underlying masonry. We take readings at multiple depths to distinguish surface dampness (condensation) from deep masonry dampness (rising or penetrating damp). Readings above 20% in masonry typically confirm rising damp; readings high on the surface but dry behind confirm condensation.

7. Salt content in plaster

Rising damp carries hygroscopic salts (mainly chlorides and nitrates) up from the ground. Those salts contaminate the plaster permanently — even after the source is fixed, salt-contaminated plaster will keep pulling moisture from the air and looking damp. The surveyor checks for salt deposits visually (white efflorescence) and sometimes with a salt-test strip on a sample. This determines whether replastering is needed alongside DPC treatment.

8. Drainage, guttering and roof line

A quick look up. Blocked gutters, leaking downpipes, broken tiles, slipped flashing — penetrating damp's most common cause is a roof or gutter defect, not a wall problem. Fixing a £40 length of guttering can save you a £4,000 unnecessary chemical DPC.

What you'll be asked

Expect questions like:

• How old is the property, and have you had any major works (extensions, render, double glazing, loft conversion) done recently?
• When did you first notice the damp, and is it getting worse?
• Is it worse in winter, summer, both, or unrelated to season?
• How is the property heated, and how is it ventilated (extractor fans, trickle vents, opening windows)?
• How many people live in the home? Do you dry clothes indoors? Cook with gas?
• Have you had any damp work done before, and by whom?

The lifestyle questions aren't intrusive — they're diagnostic. A 5-person household with no extractor fans drying clothes on radiators in a 1930s semi is a textbook condensation setup. A 2-person household in a Georgian terrace with new render and rising damp at the front wall is a textbook bridged DPC. The story matters.

The written report — what you actually get

Within 24-48 hours of the visit, you receive a written report containing:

• Diagnosis — what you've got, in plain English, with the evidence that led to it.
• Photos — annotated, of every defect and reading.
• Cause vs symptom — the underlying cause separated from the visible damage. (Mould on a bedroom wall is a symptom; cold-bridge plus poor ventilation is the cause.)
• Recommended fix — usually one option, sometimes two if there's a fork (e.g. PIV unit at £900 or full ventilation strategy at £1,800).
• Fixed-price quote — itemised, valid for 60-90 days, no hidden extras.
• Guarantee terms — what's covered and for how long, in writing.

The whole point is that you can take it to a builder, surveyor friend, or another damp company for a second opinion. That's healthy. We'd rather you trust the recommendation than feel railroaded.

Free vs paid surveys — what's the catch?

Two legitimate models exist in the UK:

Independent paid survey (£150-£300): a chartered surveyor or specialist with no commercial interest in the fix. They diagnose, write a report, and send you to whoever you want for treatment. Useful for high-stakes situations — mortgage retentions, legal disputes, heritage properties, contested party-wall damp claims.

Free contractor survey: the company that would do the treatment surveys for free, on the basis that some surveys turn into jobs. Most UK damp work is done this way. The catch — when there is one — is high-pressure sales. Some contractors will quote inflated prices, then "discount" them on the day if you sign now. That's the warning sign. A reputable free survey ends with "here's the report and the quote — call us if you want to proceed."

Our model is the second, without the pressure. Free survey, written report, fixed-price quote that's the same price next week as it is today. More on how we work.

What happens after

Three things can happen after a damp survey:

1. You book the work. Treatment scheduled, deposit on day-one (not on the survey day), guarantee in writing on completion.
2. You go elsewhere. The report is yours — take it to another contractor, a builder, or a chartered surveyor. We'd rather you trust the diagnosis than feel cornered.
3. You do nothing. Sometimes the diagnosis reveals it's not as bad as it looked, or the fix is something simple you can DIY (clearing a gutter, opening a vent). That's a good outcome too. No charge.

About a third of our surveys end up in option 3 — the homeowner thought they had a £4,000 problem and actually had a £40 one. That's fine. Damp problems often look worse than they are.

Red flags — when to walk away from a surveyor

If the person inspecting your damp does any of the following, leave the room:

• Quotes a price on the spot before writing a report. Diagnosis comes first, price second. Anyone reversing that order is selling, not surveying.
• "Today only" or "if you sign now" pricing. Damp doesn't expire by Friday. Fair pricing is fair pricing.
• Won't put the diagnosis or guarantee in writing. If they won't write it down, they don't believe it.
• Skips the outside of the property. External inspection is non-negotiable. If they don't walk the perimeter, they don't know what they're looking at.
• Recommends chemical DPC injection without showing you a moisture-meter reading above 20% in the masonry. Injecting unnecessary DPC is one of the most common rip-offs in UK damp work.

Booking a survey

If your home is in Greater Manchester, Lancashire, Yorkshire, Merseyside or Cumbria, we cover you. Take the 2-minute self-check and we'll be in touch the same day to book a slot.