Damp Check Before You Buy: Why It Can Make or Break a Van

No single fault destroys the value of a used campervan faster than damp. A van can be immaculate on the outside and still hide years of trapped moisture behind its panels, rotting the timber frame from within. The cost of putting it right can exceed the price of the van itself, which is why a proper damp check belongs at the top of every buyer's list.

How water gets in

Damp almost never comes from one dramatic cause. It seeps in slowly through failed roof seals, perished window seals, awning rails and poorly sealed locker hatches. On older vans the roof join is the classic weak point. Once water enters the space between the inner and outer panels, it stays there — the panels are effectively a sealed cavity, so moisture has nowhere to drain to and rots the wood inside.

Spotting the signs without any kit

Your eyes and nose will find the worst cases:

• Yellow or brown staining on the ceiling or wall panels, especially at the corners.
• Bubbling or peeling wallpaper and lifting trim.
• A musty, earthy smell that lingers on a dry day.
• Soft, spongy areas when you press walls, floor edges and the cab rear.

If you see any of these, treat them as red flags rather than haggling points — they indicate an active or recent leak.

Using a moisture meter properly

A moisture meter is inexpensive and is the single best tool for a viewing. Check panels across the van in a grid pattern: the roof, both walls, the floor edges, and the corners around every window and rooflight. Aim for readings below 15%. Readings between 15% and 20% need a careful look at what is nearby. Anything consistently above 20% means real trapped moisture, and a professional habitation check should be your next call.

A high reading on one isolated spot can be down to condensation. High readings on several panels, or across the roof, almost always mean a leak.

What a professional damp check adds

A moisture meter finds surface moisture, but a professional habitation check goes further. Specialists use thermal cameras and calibrated meters to map the whole van, and they test the gas and electrical systems in the same visit. Most UK habitation services will provide a written report you can use to negotiate. If a seller refuses to allow one, that refusal tells you everything you need to know.

When to walk away

Widespread damp, a soft floor, or signs the roof has been patched are reasons to walk away even if the price looks tempting. The repair cost rarely stays within budget, and a damp van keeps returning. When the checks come back clean, though, a van is a sound buy — browse campervans for sale and start your own pre-viewing checks with confidence.