Sealing the underside of the floor

[rh44mag]

I have a 1995 Rockwood Freedom.  THe floor is a little spongy at the door from use not from water.  I have devised a plan to reinforce that spot but I am less than impressed with the quailty flooring.  They used rather thin osb and I am concerned with possible water damage from the road.  Has anyone ever seal the bottom of a popup? Does the floor need to "breath" ?  Would automotive undercoating work?

[Jeremy]

You don't want to seal the factory flooring bottom as water can get in the "edges" and won't have a way to dry out.  
 
 But, if you're going to put in a "patch panel", you may want to seal that piece unless you can find out what kind of coating the manufacturer uses.
 
 Can anyone else confirm?

[brainpause]

I agree with what Jeremy said.

Larry

[Lumberdude]

Hello All.

My name is Steve and I have 1999 Coachmen Hunter 1060 with the storage trunk up front and noticed that in the front corners the OSB is pretty much gone and you can push your fingers right thru the vinyl floor covering. Just wondering if any ony else has had this problem and what a good fix would be. I saw this post on sealing the underside of the trailer ands it perked my interest    
as to what some one else thought. There is a 6" triangle in both front corners that are pretty much gone.

Thanks Steve

[Old Goat]

Two years ago I had a problem with the OSB floor in the front storage trunk of my 01 Niagara. The side edges swelled up from moisture which caused both side panels of the trunk to warp at the bottom. This kept the side access door from sealing when closed and allowed water to poor in when travelling in rainy weather. Coleman's warranty replaced the floor along with a whole new storage trunk which I installed myself. Before installing, I removed the floor from the new trunk and gave the bottom and edges two coats of urethane varnish. I have since applied a coat of urethane to the underside of the trailer floor. OSB is a very porous material and a coat or two of urethane applied to the under side can not seal it completely as a coat of thicker undercoating would do...There will always be plenty of pin holes and cracks to allow any moisture trapped inside to evaporate...Also, urethane will stabalize the underside of the floor and not allow it to flake and soften up as OSB will do from repeated wetting....We often have to travel in rainy weather during some of the long trips we take and I have had no more problems with floors getting soft and swelling.............