Thermal Imaging Leak Detection: What the Camera Shows and When It Adds Nothing
Infrared leak detection means a thermal imaging camera, which shows surface temperature as a picture, and a wet or leaking area is often a different temperature from its surroundings. It points to where to test next. It cannot see water, and it adds nothing on some floors and walls. A survey is charged at £180 an hour. No VAT is charged.
What the visit covers
- Scanning walls, ceilings and floors for temperature patterns that follow a pipe or a wet area
- Taking a visible photograph and a thermal image of the same spot, with the colour scale shown
- Checking each pattern with a moisture meter or a pressure test before calling it a leak
- A written report of what was found and where, with the paired images
Published prices
What it costs
- Fixed-price leak location package
- The package gives one fixed price, known before the visit, to locate a leak in one property using whichever methods the leak needs.
- £580Fixed price
Or by the hour
- Standard leak detection
- General water leak detection in a property.
- £180an hour
No VAT is charged
A fixed hourly rate that cannot rise on the day
No find, no fee applies when a live leak inside your own property cannot be located. No find, no fee in full
Order of work
Set the scene
Heating and water use are noted first. A camera sees little on a cold, still house with the heating off, and a lot after a hot tap has run through a pipe.
Scan and pair
The surface is scanned, and any odd patch is photographed twice: once in ordinary light and once through the camera, with the same framing.
Test the pattern
A cold patch or a warm line is a prompt, not a finding. A moisture meter or a pressure test says whether water is there.
Report what it showed
The report records each pair, the scale printed beside it, and what the next test showed. Where the camera showed nothing useful, it says so.
What a thermal image is, and what it is not
The camera measures infrared energy leaving a surface and displays it as colours or shades of grey. It does not look through plaster or tile. A pipe under a floor shows only if its temperature changes the temperature of the surface above it, and a damp patch shows only if the water makes the surface cooler or warmer than the dry area beside it.
The Carbon Trust, writing about thermography for traditional buildings, makes the point that how reliable a pattern is depends on emissivity and reflectivity. Brick and plaster are high-emissivity and suit the camera well. Metals and glass are low-emissivity and reflect the temperature of whatever is nearby, so a shiny pipe or a window can give a false picture. The same source gives a working minimum of 5 degrees Celsius between inside and outside for building surveys, and 10 degrees is more common.
The colour scale printed beside an image sets what each colour means for that picture. The same orange can be a few degrees apart in two images, so images are never compared by colour alone. Each pair in a report shows its own scale. A phone-sized camera reads less than a survey camera, and what a phone thermal camera can show compares the two.
Is infrared leak detection the same as thermal imaging?
Yes. Infrared leak detection and thermal imaging are one method: a camera reads the infrared energy a surface gives off and shows it as a temperature picture. It is not a stronger test. It cannot see water or look through plaster, so a pattern still has to be checked with a moisture meter or a pressure test.
| The infrared camera | Shows | Does not show |
|---|---|---|
| Surface temperature | Cool or warm patches and lines on a wall, ceiling or floor | What is behind or under the surface |
| Water | A temperature change where water alters the surface | Water itself, or whether a pipe is leaking |
| Pipes | A warm line when hot water has warmed the surface above | A cold pipe, or a pipe under thick screed |
When the camera adds nothing
Thick screed, deep slabs and well-insulated floors spread heat so widely that a small leak can leave no pattern at the surface. A leak at the same temperature as the surface around it cannot be seen. A cold house with no hot water running gives a pipe nothing to show, and the notes on thermal surveys in cold weather set out when winter helps and when it hides the signal. Carpet, rugs and furniture hide the surface the camera needs. Reflective surfaces such as steel baths and glossy tiles show the camera its own surroundings.
In those cases the answer comes from another method, such as tracer gas or acoustic detection. A damp-wall job in SW3 used the imager among several tools and the case record reports that the pipes held pressure and no plumbing leak was found. The camera was one of several tools, and the result was to rule the pipes out.
A cool patch on an image is a reason to measure, not a finding on its own. See reading a thermal image colour scale.
What a thermal imaging survey costs
Thermal imaging is used as part of a survey and charged at the hourly rate for the visit: £180 an hour. No VAT is charged, and the rate is a fixed hourly rate that cannot rise on the day.
A thermal survey of one property can instead sit inside the £580 detection package, with the camera and any follow-up method under one price. The thermal imaging survey cost guide compares the two.
Paired images of a ceiling stain or damp patch go into the written report, which is the record an insurer assesses if a claim is made. Cover depends on the policy and the insurer decides; see insurance-covered leak detection.
If the leak cannot be located
No find, no fee applies when a live leak inside your own property cannot be located. A leak that belongs to a neighbour, a communal pipe or the water company main is a located leak and is charged. A visit that shows no leak exists is also charged, because ruling a leak out is the answer.
Sources and dates
Statements about emissivity, reflectivity and the 5 and 10 degree temperature differences come from the Carbon Trust article on thermography for traditional buildings, read in October 2026. Statements about job outcomes come from our own case record.
Questions customers ask
What is infrared leak detection?
It is the use of a thermal imaging camera to read infrared energy from a surface and show temperature differences that can point to a leak. The pattern is a prompt to test, not a finding. It is part of a survey at £180 an hour. No VAT is charged.
Can a thermal camera see a leak through a wall?
No. It reads surface temperature only. A wet area can change the temperature of the surface above it, and that change is what shows.
Will it work in summer?
It can, but it often works less well. The method works best with a clear difference between inside and outside temperature, and the Carbon Trust gives 5 degrees Celsius as the working minimum for building surveys.
Does a cold patch mean there is a leak?
No. Condensation, a cold bridge, draughts and rain all make cold patches. A moisture reading or a pressure test settles it.
How much does it cost?
It is part of a survey at £180 an hour. No VAT is charged. The package for one property is £580.