Monday, September 25, 2023


How to locate roof leaks

[Editor’s note: This information is provided by roof membrane manufacturer Dicor. While there may be plenty of “promotion” for their product included, some of the information and principles may be of assistance to our readers.]

Being careful, get on your roof and feel around. Soft spots can indicate loose roofing material and damage to the substrate, composed of anything from 1/4-inch lauan to 3/4-inch plywood layered over trusses. Structural integrity can be seen by looking for low spots or ripples in the roofing, which means the roofing material or substrate is failing. That can lead to cracked substrate and areas of depression where water can pool and eventually cause further damage and leaks.

With rubber roofs (EPDM or TPO), look for areas that may be swollen or uneven in thickness, including the “ripple effect.” Cleaners that use petroleum distillates (including many household cleaners) can loosen the roofing material from the substrate, compromising the roofing’s integrity and making it more vulnerable to damage.

Check for punctures and cracks and areas where they’ve been patched. See if the patches are well sealed: push on them to feel any softness underneath which means there’s damage that could worsen.

CHECK THE SEALANT around the edges and around skylight hatches, antennas and other objects that stick out of your roof. See if the sealant is cracked or loose (can you pull some of it off?) or curled at the edges — a prime source for leaks. Also, look for dirt streaks heading underneath seals in low spots. If you pull on the loose sealant and the dirt continues underneath then water is probably getting past the sealant and might have caused water damage in the structure.

Regular inspections can help you identify a problem when something “looks different” from your previous inspection and can prevent leak problems before they cause costly damage.


Russ and Tiña De Maris
Russ and Tiña De Maris
Russ and Tiña went from childhood tent camping to RVing in the 1980s when the ground got too hard. They've been tutored in the ways of RVing (and RV repair) by a series of rigs, from truck campers, to a fifth-wheel, and several travel trailers. In addition to writing scores of articles on RVing topics, they've also taught college classes for folks new to RVing. They authored the book, RV Boondocking Basics.


  1. I’ve never pressure tested a RV, but have pressure tested military equipment similar to an RV. You have to be careful not to use too much pressure and seal doors and openings with Duck tape. We used air pressure from a compressor hooked to a test fixture hooked up to manometer. Manometer reading was provided by engineering. Older equipment used a lower manometer reading than new units. Too much pressure will blow out caulking and sealant around fasteners. We sprayed the equipment down using a paint sprayer/gun with a soapy water solution. We used dishwashing soap such as Joy. Spray the entire unit down not just seams and fasteners. This way your also checking for pin holes that might have corroded thru. From experience, I always felt that some times dirt and small debris could clog small holes and not show any leak. But this was the best test for leaks. Be careful because RV’s may not have been designated to pressure test, especially older units

  2. Recently, while we ‘lived’ in Houston for almost eight months, we found leaks by watching water pour in under our bedroom window during one of those monsoon downpours Houston is famous for. We also found a leak in the skylight above our shower the same way. Neither of these leaks showed up in the previous eight years we’ve had our trailer!

    As an aside, we sure got out of there in time!

    • The equipment used to test RVs for any water leaks is made by SEALTECH. Check their web site for locations. Most large RV service locations have their equipment. They can pressurize any RV through the ceiling fan opening and use sprayed soapy water that will form a bubble where air is leaking out of the RV and any potential water leak can form. Just like finding an air leak in a tire or propane line but larger. Stay safe, Stay well, Save travels

  3. A visual inspection is good but will not necessarily locate the leak(s).
    A leak can be at one place on the outside and travel to an entirely different place inside. An easy way to find leaks is to pressure test the coach/trailer.

    Basically, while you pump air into the closed vehicle with a blower or fan, spray the outside seams with soapy water. You will see bubbles where the leaks are. And, not just on the roof but at seams, vents, and around windows.

      • Interesting idea. We have a leak and can not find it all. A few times when it has rained we have seen water come in over our door. So yesterday we went around to all the stuff on top, the awning, and even the trim and put a hose over it and still couldn’t get it to leak. We even tilted the RV different ways.


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