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RFAlward
Flooring over Deck

I live in Southwest Ohio. I have a porch that I am turning into a three seasons room with windows and screen. The floor of the porch is deck boards with gaps inbetween each. I need to lay down a sub floor so I can put down a wood or tile floor to finish the room. I need to know what is the best way to go about sealing under the subfloor from moisture and the best material to use for a sub floor. I was thinking of using plastic vapor barrier and marine plywood. Will this work? Is there a better way to go about this. The porch is about 2 ft above ground.

Re: Flooring over Deck

Hello from WI. here is a proper way to do this. Remove all deck boards, use 1/2" plywood or OSB under side. Depending on you joist sizes, use 2" foam styrene inside joist bays, fill remaining with fiberglass, then vapor barrier the 1/2" OSB subfloor. Toasty! I have done probably 50 of this in my past 30 plus years! Hope this helps. Good Luck and enjoy!;)

If you already have the building framed, and you now have the deck boards showing inside, you can place down vapor barrier, felt paper then OSB. Then you will have to do the insulating part under the deck. Hope you can understand what i mean.

RFAlward
Re: Flooring over Deck

Thanks for the reply.
Keeping the porch warm in winter is not a big concern. Keeping out moisture is the concern

susieski
Re: Flooring over Deck
RFAlward wrote:

I live in Southwest Ohio. I have a porch that I am turning into a three seasons room with windows and screen. The floor of the porch is deck boards with gaps inbetween each. I need to lay down a sub floor so I can put down a wood or tile floor to finish the room. I need to know what is the best way to go about sealing under the subfloor from moisture and the best material to use for a sub floor. I was thinking of using plastic vapor barrier and marine plywood. Will this work? Is there a better way to go about this. The porch is about 2 ft above ground.

I just turned my porch into a 3 season room. You might want to have a carpenter look at it. The supports were inadequate and had to be redone. I had to have it all ripped out and start from scratch. Well worth it in the long run.

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