Leaks

[allisondtack]

We have water sitting below one of the dinette benches of our trillium 4500. Any recommendations as to where to look for the leak? It also appears that there is plywood built into the bottom in the middle of the fibreglass. Is this normal?

[thrifty bill]

Yes, there is plywood in the middle of the floor, and once it rots, you have a BIG problem. So keeping your trailer dry is critical. Read up all the threads on the windows and belly band. Both are extremely common leak sources, pretty much both will leak unless repaired.

You will also find exposed plywood under the kitchen cabinets and under the gaucho too, if you have a front gaucho. Rot in those areas is worse.

Two layers of fiberglass would not support the weight of someone standing on the floor. Many assume the floor is fiberglass. It's not. The floor gets its strength from the plywood. Most fiberglass trailers use plywood or OSB for this. Some have the wood sandwiched between layers of fiberglass, some don't. Being sandwiched protects it more, but makes it a lot harder to repair/replace. People also think molded FG trailers are indestructible. They are not. They just are a lot better than their stick built cousins.

Trilliums are great, but have some well known flaws. Left unfixed, they can ruin the trailer.

Go to the manufacturers section top of the page on the right, and read up on belly band repair and window repair. Both have been covered in depth many times. Lots of good info out there. There are more issues too, like body to frame bolts, and the door hinge attachment.

I rejected the first two 4500s I looked at, one had standing water in the dinette benches (it was raining), the other the wood in the dinette bench was totally dry rotted. Both had soft spots in main floor (rotten plywood). Both trailers were quickly sold to others who I guess didn't look very close. I'm waiting for those two buyers to appear here: "How do I fix this?" I haven't seen either yet.


Water inside a dinette bench is something to be addressed quickly. Don't wait, get it dry, consider some small (1/4 inch or less) holes in the pontoons. Hopefully the plywood is still OK.

[John in Michigan]

As Bill said, the water is likely coming from behind the window frames, the belly band or both. You can view water trickling inside on a dry day by observing inside surfaces while someone sprays with a garden hose outside.

On our Trillium 4500, we found water leaking in behind the window frames, the belly band, as well as the fresh water fill. The city water connection and grey water connection were also leaking during use. Also test the roof vent, door/door frame, and power cable port. Yes they all leaked.

After forty years, the sealant around all fixtures attached to the shell fail. Best way to re-seal windows and other fittings is by removing, cleaning and re-sealing with butyl tape. The belly band is more complicated as described in other threads dedicated to this topic.

[allisondtack]

Thank you!

[Becky Bly]

So, I see how to fix the window leaks by removing and reinstalling the windows, but if I already find floor plywood rot, where do I go to learn how to remove the rotted wood from between the fiberglass and replace it? Is it possible to encapsulate the rotted wood and seal it off? How do you get to between the glass layers to remove the bad wood?

[John in Michigan]

Becky there are numerous threads on this forum on the topic of how to repair rotted plywood flooring, including plywood between fiberglass layers. You can search using the "Google custom search" box in the "Search" pull down tab above.

Here is an example of thread discussing repair of floor rot sandwiched between layers of fiberglass:

http://www.fiberglassrv.com/forums/f...ild-73025.html

This is one of the most difficult repairs to this type of trailer. Avoid it if possible by thoroughly inspecting the trailer before purchase, and just NOT buying the trailer...

EDIT: The Trillium is the worst case because the fiberglass furniture is permanently fiberglassed into the trailer, and the plywood is below the furniture and below the fiberglass floor. The fiberglass furniture and floor must be removed with a saw to gain access to the rotten plywood. OTOH, many fiberglass RVs have an exposed plywood floor/subfloor, as well as wood furniture that is screwed in place. Somewhat easier to fix...

[thrifty bill]

Well, that one thread above is the only successful Trillium floor repair I have seen on this forum.

It gives you an idea of how complicated it is. All of the original fiberglass floor cover is cut off to expose the plywood. That person was very fortunate that the plywood under the kitchen was good, so he cut it there. Look at the pictures carefully. You will see the person cut the fiberglass top layer off the floor, then cut out the entire front gaucho bench, and cut out a corner of the closet. Then he put one piece of plywood back in, cut to fit the hole. Then fiberglassed over the top of that.

Meanwhile, the roof has to be temporarily supported during the job. Best to have a garage where you can park the Trillium during the repair.

Such a repair is way over my skill level for sure!


If you read the various threads on floor rot (not just Trillium) and you will find a common theme, the rot is almost always much more widespread than the person thought. What may seem limited to a small spot may not be.

Certainly the way the trailer is made, if it is the dinette flooring, that could be localized and repairable. Someone posted a thread on that topic.

The beauty of the Trillium design is having all the cabinets fiberglassed in place, versus many of its competitors riveting cabinets in place. Makes for a very clean interior. Unfortunately, that beauty creates quite a challenge if you need to do a floor repair. You either have to cut the fiberglass on top of the floor, or the fiberglass under the trailer.