Subfloor plywood alternatives

[stesmit]

Anyone ever use coosa board, Thermolite or other plywood alternatives for a subfloor? How was it to work with the material and how did it turn out?

http://https://www.spaceagesynthetic...-product-line/

http://https://www.merrittsupply.com...mposite-board/

[BCam]

Links don't work for me.

[stesmit]

not sure what I did wrong there... here are the links not live for pasting into a browser. They are both a fiberglass reinforced HDPE board typically used in marine applications. Several brand names out there but these two were made in US and had the most search results

https://www.spaceagesynthetics.com/t...-product-line/

https://www.merrittsupply.com/produc...mposite-board/

[BCam]

I had a folding kayak (from the '70s) that had a folding plywood floor that was surfaced in some sort of impregnated paper. I think it's called Film Faced Plywood now and should be great for a subfloor:

https://www.eoncredgroup.com/Applica...id3967992.html

Check out your local plywood suppliers, it's commonly used for concrete forms. Home Depot shows a version but it's apparently out of stock:

https://www.homedepot.com/p/3-4-in-x...5100/202562995

[stesmit]

Nice. This looks like it could be a much less expensive option and perhaps a bit easier to source. Thanks for the suggestion!

[1der]

Make sure to check the product's ability to hold fasteners/screws. When I searched Coosa Board it was strongly suggested to not expect screws to have any holding characteristics.

[stesmit]

thanks for the note... I'm finding more details on thermolite board than Coosa. There are some detailed specs on the type of fasteners to use for specific applications and some info on torque specs for them. I can't seem to find anything on screw pull strength but I can find a number of examples of it being used for sub flooring in other RV forums and its commonly used in mass transit vehicles. The west coast distribution for thermolite is a company out of portland and the've been selling a lot of board to folks for subfloor applications. I'm doing a pretty light build and just adding some 80/20 cabinets over the wheel wells and think I won't have a lot of force on the fasteners. Still trying to land the decision. I'll keep you posted on the details if I go with a composite subfloor. Cheers!

[Fordx2]

I’m sure someone will tell me why my no-plywood sub-floor was a bad idea.

The short version…

I installed my baltic birch cabinets to the bare floor (bolted through floor). I leveled the remaining floor using lightweight body filler (after a bit of research and a less the scientific test that there was no obvious off-gas from cured filler), by filling the low areas of the floor channels. Vinyl is the finish flooring. 5 years later all seems fine. Yes it was messy with lots of sanding and it took a few coats to get things smooth. No worries about moisture penetration in plywood. No loss of height. As part of the “older” crowd, we don’t camp in extreme temperatures so I didn’t insulate the van. The vinyl is glued so I can’t include a picture.

Unless the plywood used for the sub-floor was thick, and/or the part being fastened light, I wouldn’t put much trust in the durability of something secured only to a plywood sub-floor.