Trillium 1300 center seam cauk?

[rjannunziata]

Hi,

Does anyone know if the center seam (where the two halves connect) needs to be cauked.Ours doesnt leak.

The previous owner cauked the top seam but its a messy job.
Thanks,

Rich

[David Tilston]

Rich, You are opening a BIG can of worms.

I have seen owners calk the top of the aluminum belly band, but that is, at best, a band-aid.

The anatomy of the belly band causes a long term problem. First, it is important to understand that the aluminum, and steel plates, (more on that later) are not structural. They are just a tool to line up the top, and bottom shells.

The process to connect the shells goes something like this: The top half and the bottom half are stacked with some 1/4" thick wood bits to keep them from actually touching. The belly band is then riveted, through the gap between the shells, to some 1" x 2" steel plates that are standing up vertically. These plates pull the shells out, and the belly band pushes the shells in. As they work their way around this process lines up the upper and lower shells. When they are lined up, Trillium ran a fibreglass strip on the inside of the shells to join them. This is the structure.

The biggest problem with this system is that the space that the plates occupy forms a kind of pocket. The upper pocket is no problem, but the lower pocket collects water. This water may come from rain, which the calk is meant to prevent, or it comes from condensation, which no calk can prevent. In the winter, this water freezes, and expands. This rips the pocket slightly larger. Over the course of several winters, the pocket ruptures into the inside of the trailer. Then you have a leak.

The fix is to fill the gap between the shells, and the pockets. Or, at least seal them up so that no more water gets in.

There are many approaches to this.

Mine:
http://www.fiberglassrv.com/forums/f...ead-58763.html
http://www.fiberglassrv.com/forums/f...ead-59580.html

Others:
http://www.fiberglassrv.com/forums/f...and-43322.html
http://www.fiberglassrv.com/forums/f...ion-49308.html
http://www.fiberglassrv.com/forums/f...ium-69274.html
http://www.fiberglassrv.com/forums/f...and-46424.html
http://www.fiberglassrv.com/forums/f...ml#entry338485
http://www.fiberglassrv.com/forums/f...and-44340.html

NOTE:
There is a big difference between the 1300 and the 4500 for this job. On the 4500 there is no fibreglass strip, (bandage) under the back window. The belly band is screwed into a strip of 1/4" plywood. This causes a whole other set of problems. On the 1300 the fiberglass strip goes all the way around the trailer, so it is less of a problem.

[John in Michigan]

Rich,

In its original factory condition, the center band does not have to be caulked, sealed, repaired, etc. However, leakage may start to occur if and when the steel plates into which the center band aluminum rivets are fastened start rusting. For an example of this problem see photos in the last couple of pages of my Trillium 4500 link at the bottom of this post. Once the steel plates start rusting, they expand dramatically, deforming the fiberglass, and possibly punching holes through the fiberglass band on the inside that was designed to seal the seam and hold the two halves together. Also if the plates start rusting, then the rivets start popping out. If one attempts to re-attach the aluminum trim with new rivets or screws, this usually results in holes THROUGH the inside fiberglass band which can then result in more leaking.

Again the original center seam is completely sealed by an inside/backside fiberglass band or strip that also holds together the two halves of the body.

-John