Buying a Used RV: The Water Damage Inspection Checklist

The most expensive used RV is the cheap one with hidden water damage. I get called after purchases like that, when the new owner finds a soft floor on the first trip. Water damage almost always starts smaller, higher, and farther from the stain than you expect.

You do not need to be a tech to catch most of it. You need an order, a flashlight, your nose, your feet, and one real tool — before you fall in love with the floor plan.

Start outside: roof, seams, and caps

Water gets in at the top first, so start there. If the seller will let you on the roof safely, check every seam and penetration: cap seams, vents, skylights, the air conditioner, and anything screwed through the membrane. Look for cracked, peeling, or missing sealant, patched spots nobody mentioned, and soft decking underfoot. A spongy roof is not a negotiating detail — that is rotten decking talking.

Then walk the walls, palm flat, pressing as you go. On a laminated wall, bubbles, waves, or a section that flexes and crackles mean delamination: the skin has let go, usually because water got in behind it. Check corner moldings, window frames, compartment doors, and slide seals for gaps and torn rubber. Water only needs one opening left cracked.

Use your nose before your eyes inside

Step in, close the door, and stand there for thirty seconds. A musty smell in a closed-up rig is information, and heavy air freshener is too — ask what it is covering. Then open every cabinet, especially low ones, corners, and under sinks. Check back corners and cabinet floors for staining, swelling, and spotting. Sellers clean what you see first, rarely the back corner of a bathroom cabinet.

Look up next. Ceiling stains, bubbling paneling, and sagging near vents, the air conditioner, and slide corners point to water from above. Press the wall under every window — a failed window seal quietly feeds a wall for months, and it will feel soft there long before a stain shows.

Walk the floors like you mean it

Walk every square foot slowly, in socks if the seller allows it. Your feet find soft spots your eyes miss. Hit the high-risk map: around the toilet and shower, under the kitchen sink, by the entry door, in front of the refrigerator, and along every slide-out edge. Cycle each slide fully out and in, then check its floor corners again. A soft slide floor is a big repair, not a cosmetic one — I rebuild those, and nobody enjoys that invoice.

Lift what lifts: cushions, the bed platform, and access panels. Check outside storage compartments too, including their ceilings — a stain there can be the bottom end of a wall leak that started at a window above it.

Meter it — do not guess

Feel and smell sort the obvious cases; a meter settles the arguments. I use a General Tools MMD4E pin moisture meter on wood I can reach — and get the seller's permission first, because pins leave tiny holes, so test in hidden spots or use a pinless meter on finished surfaces. Take a dry reference reading first on an interior wall away from windows and plumbing, so you know that rig's normal. Then check wall-floor joints, ceiling corners, slide perimeters, and below any stain.

For wood: below about 12 percent is dry and acceptable, roughly 12 to 16 percent is borderline, and readings past 16 percent point to active or recent intrusion. One high number can be a fluke. A pattern in one corner is a leak with an address. For spots you cannot reach, a DEPSTECH wireless endoscope through an access panel or outlet opening can show you the back of a wall before you own what is growing on it.

Run the water, then look again

Ask to run the plumbing: pump or city water on, faucets opened, toilet flushed, shower run briefly. Then recheck under the sinks, around the water heater and pump, and in the compartments below. Plumbing leaks only show under pressure, and they rot floors just as thoroughly as rain. If the seller will not let you run water, meter the walls, or open cabinets, that refusal is your inspection result.

Walk away, or price it honestly

• Walk away: a soft or spongy slide-out floor, widespread delamination, a sagging or soft roof, crumbling wood in more than one area, or high moisture readings in several corners.
• Negotiate hard: one small, dry, firm old stain with a documented repair, tired sealant with dry readings underneath it, or a single soft cabinet base you can fully see the edges of.
• Never accept: “it leaked once, we fixed it” with no paperwork, fresh paint or new flooring offered as proof, or a seller rushing you past the cabinets and roof.

None of this takes genius. It takes refusing to be rushed. Spend an hour walking a rig in this order — top down, outside in, dry reference first. Buy the dry one, even if it costs a little more. The wet one always costs more later, and it charges interest in rot. Fix it right the first time starts before you buy: do not buy somebody else's leak.

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