Caravan Guides

Caravan Damp Checks Explained

6 min read

What a damp check involves, what the readings mean and why they matter so much.

Why damp matters more than anything else

A touring caravan is built from thin bonded panels — an outer skin, insulation and an inner board, glued together. That construction is light and strong until water reaches it. Once moisture is in the panel, the bond starts to fail, the timber frame softens and the repair becomes a structural job rather than a cosmetic one. That is why damp affects the value of a caravan more than mileage, age or how the upholstery looks, and why every trade buyer checks for it first.

How water gets in

Almost always through a joint rather than through a panel. The usual culprits are perished sealant along awning rails and body seams, tired window and rooflight rubbers, screw holes from accessories fitted later, damaged sealant behind an impact you barely noticed, and blocked drainage channels that let water sit rather than run away. Caravans stood outside all year with no cover suffer most, and a caravan that has been stored nose-down can hold water in the front locker area.

What actually happens during a check

A damp meter has two pins that measure electrical resistance through the inner wall board — wet material conducts more readily than dry. The person checking works methodically around the caravan: front and rear panels, all four corners, under and around every window, inside lockers and wardrobes, along the base of the walls, around the washroom, under the bed boxes and across the floor. It is the pattern of readings that matters, not one number, so a proper check takes twenty minutes or more and covers dozens of points.

Reading the results honestly

As a rough guide, readings up to around 15% are normally treated as dry, the mid-teens to low twenties as elevated and worth monitoring, and anything above roughly 25% as active damp needing investigation. Those bands vary between meters and materials, so treat them as indicators rather than a verdict. A single elevated corner is often a failed seal that costs little to put right. Consistently high readings along a whole wall or across the floor point at something bigger. A brand-new caravan can show a raised reading behind a fitting; a fifteen-year-old caravan with genuinely dry readings has been looked after.

What to do if you find damp

Do not panic and do not hide it. Find the source before repairing the symptom — resealing a joint without drying the panel simply traps the water. Get a written report with the readings and locations, ask what the repair involves, and treat it as a cost to weigh against the caravan's value. If you are selling to us, tell us the readings up front. It does not stop a sale; it means the figure we give you is the figure that survives inspection on collection day.

Keeping a dry caravan dry

Check and renew sealant before it perishes rather than after, replace window and rooflight rubbers when they harden, keep drainage channels clear, and ventilate rather than seal the caravan up over winter — trapped condensation causes its own damage. Have a habitation service with damp readings once a year and keep every certificate. That folder of readings is one of the most persuasive things you can hand a buyer.

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