In the RV world, suspicion is a better diagnostic signal than optimism. Water intrusion has been a game of “symptoms vs source”, and unfortunately the symptoms appear late. Wood, insulation, luan, fabrics, and adhesives all soak, swell, and rot long before you see anything obvious.

The obvious tells:

• tactile anomalies (softness, sponginess, bowing, or rippling)
• surface warping in ceilings/panels
• unexplained mustiness (mold blooms well before moisture surfaces)
• discoloration, blemishes, or adhesive failures
• trim or headliner losing tension

None of these tell you where the leak(s) originated. RVs funnel water the way gutters funnel rain: through channels, substrates, and capillary paths. A roof seam failure can present as a wall stain three feet away, or as a floor problem.

This is why most DIY leak-chasing is a mix of sealant roulette + misplaced confidence. If you’re wrong, the meter runs quietly in the background and the bill shows up when you sell the RV or open a wall panel. Leak testing compresses that discovery timeline drastically — you’re swapping uncertainty for a map of reality.

Here’s how to think about DIY vs professional in a rational way.

Leaks have three dimensions:

1. Detectability (can you identify the problem?)
2. Repairability (can you fix it?)
3. Downside risk (what happens if you’re wrong?)

DIY can perform reasonably in dimension 2. If the leak is obvious and shallow (seal cracked, vent collar shot, one trim line compromised), you can fix that with materials from any RV shop.

But DIY detection is statistically weak for hidden leaks because most DIY tools rely on visual inference, and RV leaks are often non-visual until late-stage. Professionals cheat by using physics (pressure differentials), thermal gradients, moisture sensors, and flow tracing — all of which expose leaks that have no surface symptoms yet.

Now we look at dimension 3: upside vs downside.

If you’re wrong on detection, the cost of “waiting to see” compounds like interest: insulation saturation → structural rot → mold → electrical intrusion → appliance failures → resale discount.

So the rational rule is:

DIY is fine when the downside is small and you’re confident.

Professional leak testing is optimal when the downside is large or unclear.

Most RV owners don’t do that math, which is why leak repairs are rarely expensive in the moment — they’re expensive in the aftermath.

Water damage is not binary; it’s a scope + cost-to-value problem.

Three questions determine whether a repair is rational:

1. How deep is the damage? Surface damage is cosmetic. Substrate damage is labor. Structural damage is budgetary violence.
2. How wide is the affected area? A one-foot section is a repair. A whole wall is a renovation.
3. What is the RV worth? Repair cost must be considered against depreciated value — RVs don’t appreciate unless they’re classics or marketed as “luxury” (and even then, rarely).

There’s also a fourth question most owners never ask but should:  How fast is the damage propagating?

Water damage compounds; it does not stabilize on its own. If rot has begun, the timeline accelerates because moisture retention increases porosity and thermal transfer.

The emotionally hard truth:  Most RVs become “write-offs” economically before they are safety hazards mechanically.

A proper leak test + moisture mapping gives you the missing data to categorize the problem. Sometimes the fix is shockingly small. Sometimes the smartest move is to sell before the wall has to come off. Not knowing is where the real losses happen.