Of course I knew what the problem was and wrote back to say he had dry rot. To make things worse, they had just purchased the motorhome last spring and no doubt the dry rot was an existing problem. It would have been nice to have spotted it before he closed the deal.

The term "dry rot" is actually a misnomer because the decay is caused by certain fungi capable of carrying water into the wood they infest. The water can be transported far away from the source and the wood will often feel dry to the touch thus the term dry rot.

Gradually, the wood decomposes and its strength is lost. And, as Mark knows too well, such damage is often inconspicuous until it's final stages, working behind the paneling on the structural framing of the RV.

This travel trailer was in the shop to have the siding replaced due to hail damage. After the siding was rempved, the dry rot was found.
( click photo to see closup of damage )

Dry rot in an RV can be caused by an undiscovered plumbing leak but is usually caused by a leak in the outer skin which lets rain water in.

And that's about all I knew about dry rot when I received Mark's e-mail. But it got me wondering.

I couldn't find much information on the internet about dry rot in Motorhomes, Fifth Wheels and Travel Trailers so I drove over to All-Rite RV Parts and Service in Yuba City, California. If I can't fix it myself Dave Allred and Dave Stewart are the guys I call. Here's what they told me.

Almost everyone is good about re-caulking the roof seams but that's only part of prevention. Cracks can develop in the rim of plastic roof vents well above the seam. Dave said he's seen it often enough that he recommends replacing plastic vents with metal ones.

Marker lights are often the source of a leak. Make sure you at least check them each time your reseal the roof. And be sure you replace any broken or missing lenses.

Windows are a major source of water leaks. Especially the front overhang window on class Cs. Partly because they get the full force of rain while driving but mostly because they are too hard for most people to inspect. Or too easy to neglect. Dave advised those of us with RVs over ten years old to have all the windows removed and resealed.

Inspect your RV Regularly

On the outside, look for irregularities around window and door frames. If you have screws that won't stay tight you may have a problem. If the screws are rusted or corroded you DO have a problem and it's a good indication of dry rot.

A day or two after you've washed your RV or after a rain storm check along the bottom edges. If it is still wet you probably have a leak. Check it out.

On the inside, look for water marks on the ceiling especially around roof vents. Remove the vent flanges and air conditioner shrouds and look for discoloration in the wood. That's a sure sign of a leak and possible dry rot.

And, of course, check around the windows. Look for discoloration, softness of the paneling and loose screws.

Get any Problems in Your RV Fixed

Repairing the leak is only part of the repair. You must make sure the wood is dry. If there is any sign of dry rot treat the wood with an antifungal solution. Dave says regular household bleach works for him but there are commercial formulas of disodium octaborate tetrahydrate or sodium borate with brand names of Bora-Care�, Guardian�, Jecta�, Shell-Guard�, Tim-bor�.

If the wood has decomposed enough that the screws won't hold, don't just put in longer screws! Dave and Dave said Git Rot, an epoxy like product, can rebuild dry rotted wood, but if you wait until the long screws won't hold there may not be enough wood left to rebuild.

No doubt dry rot is responsible for the early death of many Motorhomes, Fifth Wheels and Travel Trailers simply because it isn't spotted and repaired before it gets out of hand. Your RV doesn't have to be one them.

The repairs to Mark's RV wound up costing him $7,000! The good news is his motorhome is nearly as good as new and has many more miles left to go.