Coosa board

[Tomo2]

Has anyone used coosa board before? Specifically has anyone used it as a plywood alternative for their subfloor?

[gordon2]

Tom, I hope you do recall that you asked the same question two weeks ago:

https://www.fiberglassrv.com/forums/...ace-96411.html

[Tomo2]

Originally Posted by gordon2

Tom, I hope you do recall that you asked the same question two weeks ago:

https://www.fiberglassrv.com/forums/...ace-96411.html

Thanks for the reminder. However I did not ask about coosa board specifically. I thought a thread about a specific material could create a good conversation. I plan on using coosa board for my subfloor and hope others might chime in with their experiences with it.

I will be using coosa bluewater 26.

[gordon2]

I took the video link in your second post as a continuation of the question in the first post. The video is only about Coosa. But of course someone would have to open the video to see that.

It will be interesting to see how it works for you. I did see some prior mentions of Coosa board in floor replacement in other threads on this forum but from a quick check it was not apparent if someone actually used it. Stephen suggested it but he has not been on the forum about three years now.

[New Orleans John]

Originally Posted by Tomo2

Has anyone used coosa board before? Specifically has anyone used it as a plywood alternative for their subfloor?

From my readings on the Airstream Forum; many use it to replace the old rotten plywood floor on their shell off rebuilt. New Airstream as of 2021 do not use plywood anymore.

[thrifty bill]

Don't limit your search to molded FG. Almost all RVs have vulnerable floors. I have heard of people using Coosa board on Airstreams.

Google will get you the Airstream Coosa threads.

[Tomo2]

It’s going to cost twice as much as plywood but will only require fiberglass on the seams. Plus it has 2-3 times the r value of plywood which could be nice for fall camping. 40-60% lighter than plywood will be nice too. And the obvious no rot or mold.

https://coosacomposites.com/the-coosa-advantage/


3/4 Marine grade plywood locally $150
3/4 Coosa board locally $305

[David Tilston]

Originally Posted by Tomo2

It’s going to cost twice as much as plywood but will only require fiberglass on the seams. Plus it has 2-3 times the r value of plywood which could be nice for fall camping. 40-60% lighter than plywood will be nice too. And the obvious no rot or mold.

https://coosacomposites.com/the-coosa-advantage/


3/4 Marine grade plywood locally $150
3/4 Coosa board locally $305

or...

1" yellow pultruded grating, (I would also spray foam the voids) at Grainger $734
https://www.grainger.com/product/SAF...ultruded-4AUA4

and/or

1" yellow higher density pultruded grating, (still spray foam) at Granger $894.45
for those high load applications
https://www.grainger.com/product/SAF...ltruded-49AL06

and/or

1" grey pultruded grating, (spray foam) at Granger $737.06
https://www.grainger.com/product/SAF...ltruded-49AK87

and/or

1" grey higher density pultruded grating, (foam) at Granger $941.79
for those high load applications
https://www.grainger.com/product/SAF...ltruded-49AL24

and/or

1" grey smoother pultruded grating, (foam) at Granger $861.73
I think I like this best
https://www.grainger.com/product/FIB...ltruded-49AK69

and/or

1" grey lower density, smother pultruded grating, (foam) at Granger $682
for those low load applications
https://www.grainger.com/product/FIB...ltruded-49AK66

and/or

1" grey molded grating, (foam) at Granger $767.60
https://www.grainger.com/product/FIB...-Grating-4ATX6

and/or

1" orange molded grating, (foam) at Granger $853.96
https://www.grainger.com/product/FIB...Grating-16U497

All options are a 4' x 8' sheet, (also available in 3' and 5' widths) with the strength in the 8' direction. Other than the molded grating, (last two).
One thing I like about the pultruded grating is that you can run wires through it, before the spray foam. The molded grating would make this difficult. However the molded grating can support loads accross the width and span.

[Tomo2]

Originally Posted by David Tilston

or...

1" yellow pultruded grating, (I would also spray foam the voids) at Grainger $734
https://www.grainger.com/product/SAF...ultruded-4AUA4

and/or

1" yellow higher density pultruded grating, (still spray foam) at Granger $894.45
for those high load applications
https://www.grainger.com/product/SAF...ltruded-49AL06

and/or

1" grey pultruded grating, (spray foam) at Granger $737.06
https://www.grainger.com/product/SAF...ltruded-49AK87

and/or

1" grey higher density pultruded grating, (foam) at Granger $941.79
for those high load applications
https://www.grainger.com/product/SAF...ltruded-49AL24

and/or

1" grey smoother pultruded grating, (foam) at Granger $861.73
I think I like this best
https://www.grainger.com/product/FIB...ltruded-49AK69

and/or

1" grey lower density, smother pultruded grating, (foam) at Granger $682
for those low load applications
https://www.grainger.com/product/FIB...ltruded-49AK66

and/or

1" grey molded grating, (foam) at Granger $767.60
https://www.grainger.com/product/FIB...-Grating-4ATX6

and/or

1" orange molded grating, (foam) at Granger $853.96
https://www.grainger.com/product/FIB...Grating-16U497

All options are a 4' x 8' sheet, (also available in 3' and 5' widths) with the strength in the 8' direction. Other than the molded grating, (last two).
One thing I like about the pultruded grating is that you can run wires through it, before the spray foam. The molded grating would make this difficult. However the molded grating can support loads accross the width and span.

Interesting - so you are using this on top of your subfloor/under your flooring?

[David Tilston]

Originally Posted by Tomo2

Interesting - so you are using this on top of your subfloor/under your flooring?

I have not used it yet. In Trilliums, there is a sheet of ¾" plywood in the floor. It is sandwiched between the floor of the trailer, and the outside shell on the bottom. Some have had it rot to nothing. I have been considering the idea of a 100 year trailer rebuild. I decided that it would be necessary to eliminate any wood in my trailer rebuild. The wood in the floor and the inside framing around the windows are the only place that Trillium uses wood. I would install the grating in place of the plywood. To do this, I would have to cut the bottom off the Trillium.

It should be noted that since Trilliums are not much more than 6' wide, I would not require the 8' long grating. Fortunately it is sold in many lengths and widths. I don't believe that Granger is the least expensive place to buy it though. When I am in a place to purchase, I will be shopping around.

In exploring alternatives to wood in the floor, I looked at the foam that is used in foam sandwich construction on boats. It is almost as expensive as pultruded grating. The grating seemed like a stronger solution, so I settled on that idea. It is ¼” too thick, but I think I can compensate for that during the install. What I am looking for is a Trillium 4500 with the floor rotted out, to try this on. Most, "For Sale" ads don't advertise this.

[Mo L.]

Originally Posted by Tomo2

Has anyone used coosa board before? Specifically has anyone used it as a plywood alternative for their subfloor?

Hey tom- we used coosa and it turned out amazing. We are so happy with our Bluewater 26 subfloor. I highly recommend going on the Burro facebook group and searching for coosa board in the search function- you will find a lot of helpful resources- let me know if you have any questions!