Test for dampness by checking for visible or musty signs, then comparing the suspect area with a dry area of the same material using a moisture meter. This can identify possible excess moisture, but it cannot confirm the cause. Compare the pattern with the common causes of damp before deciding which specialist to contact.
Check for signs of damp
Inspect during dry weather and, where practical, again after rain. Look at:
- ceilings and wall-to-floor junctions
- walls around windows, showers and plumbing fixtures
- floors, skirting boards and accessible spaces beneath sinks
- areas behind furniture that can be moved safely
- surfaces for stains, bubbling paint, lifting wallpaper, mould or white crystalline deposits
- plaster, timber and skirting for warping or unusual softness
- rooms and cupboards for persistent musty smells
Note whether signs appear after rain, showering or water use. Old stains may remain after a leak has stopped, and mould or peeling paint alone does not identify the cause. Look for other clues that a water leak is causing mould rather than assuming the two are connected.
You may lightly check whether an intact surface feels unusually cool or damp. Do not touch mould, sewage-contaminated material or wet areas near electrical fittings. Do not open walls, lift fixed flooring or enter confined roof or subfloor spaces.
Use a moisture meter
Take several readings across the suspect area and compare them with an apparently dry area made from the same material. Follow the meter manufacturer’s instructions and select the correct material setting where available.
Pinless meters can check walls for moisture without making holes. Avoid inserting meter pins into finished walls because concealed cables or pipes may be present.
Record readings in a simple grid and compare like with like, such as plasterboard with plasterboard. Different materials and finishes respond differently, so do not treat the displayed number as a universal moisture percentage unless the manufacturer confirms that interpretation.
Metal, concealed pipes, foil insulation, salts, coatings and variations in material density may affect readings. A pattern of elevated readings is more useful than one high result, but it still cannot prove condensation, rising damp or a concealed leak.
If condensation is suspected, record room humidity and temperature at similar times over several days. Note the weather, ventilation, showering and cooking. If the pattern is concentrated in a bathroom, check which ventilation option best prevents mould. A single reading is not conclusive.
When to arrange an investigation
Seek professional investigation if elevated readings persist or spread, materials soften, staining returns, deterioration progresses or moisture appears after rain or water use.
If water is actively leaking, turn off the main water supply only if the valve is safely accessible. Keep away from wet electrical fittings, switches and appliances, and arrange urgent assistance. Do not disturb suspected asbestos-containing material or areas affected by sewage.
A plumber can investigate suspected leaks from water services, drainage or roofwater plumbing. Other patterns may require a suitably qualified building, waterproofing or damp specialist. If results suggest a concealed plumbing leak, contact our leak detection team for professional investigation.