Water damaged subfloor, how to replace advice?

We traveled a lot during the Winter months and we found that in the front and rear fiberglass end caps, they used fiberglass batt insulation that had sagged. This allowed the interior surfaces to sweat from the cold outside and the moisture inside. We discovered it when it was dripping on to our dash. I removed all cabinets so I could get to the inside of the fiberglass end caps and used two part closed cell spray foam to insulate the inside of the fiberglass. This took care of the problem and made the coach much more comfortable in the Winter, at least down to -5 during one trip.
You might want to check your end caps because Monaco was using fiberglass in 1990 and it could have sagged away just like ours did and allowed a lot of moisture to develop inside the coach.

ok no osb, no idea on how thick either. I guess i'll find out soon enough.

Think I'll need to remove the bed platform and all the cabinets?

It's hard to tell if the carpeting went in before or after the wood work was installed.

where is the water coming from you ask ?

when it snows then melts, the water has to go somewhere and in this case the leaky air conditioner base seals allowed the pooling water easy access. The once painted air vent covers are a dead give away now quite rusty.

Before winter sets in this year i'll have tarps covering the roof a bit better.

I am not sure about 1990 but I know in later years they used a sandwich type of floor with styrofoam between two sheets of flakeboard. It was about 2.5" thick.

Find the leak before you do anything! Remember, all the walls, carpet and flooring are on TOP of the plywood.

GDS-3950BH wrote:
Use exterior rated plywood. For a the minimal amount you'll need marine grade would be a wise choice ($70-$80 sheet).

I agree, don't cheap out on the flooring. midnightsadie is correct. It shouldn't get wet but, if it does you don't want to replace the floor again.

Now is not the time to use the OSB you have on hand. Save it for another project.

#1 find the source of the water, could use marine plywood . or just reg plywood after all its not suppose to get wet in that area.

OSB = Optimal swelling board. It's cheaper than plywood and perfect if it is never going to take on any water. Did you ever see what happens to OSB sub flooring if a builder drags his rear end and does not dry in a new house quickly while building it? I've seen every T&G and butt joint swell to where they need sanded or hit with a grinder prior to floor coverings. I have also seen sheets of the stuff that swell up from 3/4" thick to over 1" from taking on some H2O.

Use exterior rated plywood. For a the minimal amount you'll need marine grade would be a wise choice ($70-$80 sheet).

Do yourself a favor don't use OSB board. That will deteriorate when damp or wet.
One of the worse products to use. Use Advantech it will hold up to standing water.

Carefully