Does the bottom of a popup floor need to be sealed?

Sealing up the underside of a Fleetwood or Coleman would go against what Fleetwood and Weyerhaeuser (actual manufacturer) say for the Structurwood used. Sealing it would actually trap moisture in the wood.

I quote the 2008 Fleetwood folding trailer brochure:

"Weyerhaeuser agrees with Fleetwood's practice of not coating the exposed bottom surface of the Structurwood panels used in their trailers. In our opinion, moisture from occupancy load, or from other internal or external sources may become trapped in the Structurwood substrate if it is coated on the underside with a system that impairs the ability of the substrate to dry thoroughly. Trapped moisture, over time, may cause premature decay or rot." Weyerhaeuser

I had a Jayco that had OSB wood for the underside. I don't know if it was Structurwood or not. It had a coating on it. Several wafers had peeled and warped. You could tell it had not come that way from Jayco as there was no coating underneath the wafers that had warped. I am left with only the conclusion that water was the cause and might not have had that effect if it were allowed to pass through unimpeded.

I don't see anything wrong with putting a breathable membrane underneath but I sure wouldn't seal it up.

A friend was looking at used popups and found several of them (including a Coleman) with rotting OSB floors on the underside. So yes, I would seal it up.

Interestingly enough, the OSB flooring on my old '97 Viking Legend 2480 appears to have been treated with some sort of water repellant. Being Central Arizona mountain dwellers, we don't camp in the rain a lot either, but as you might suspect, it's not by choice as it may be in Southern California. We love the wet stuff, especially the late afternoon rains during the monsoon season, and the spectacularly cool evenings and mornings that follow, until the next afternoon's shower. I'm thinking you're right - it must be to protect the flooring from the road spray while towing in the rain.

My 2008 STARCRAFT 14RT off-road version POPUP uses OSB Particle Board material for the flooring. Have no idea if this is better or worse from Regular Plywood or Marine Plywood.

Have not had any issues with my floors and we camp alot off the power grids.

My flooring is not protected from the bottom using any of the underbelly membrane type material.

The OSB flooring looks the same to me as it did when new... You can identify OSB flooring with all of the small wood items all glued together...



NOTE: after seeing RIMCOUNTRYs comment I went and looked under my Starcraft 14RT OFF-ROAD POPUP and it does indeed have the black colored coating applied to the bottom only. On top it does not have this coating when looking inside cabinet floors etc...

Roy Ken

OOPS