question for sealing old plywood before finishing

[jHop]

What is the best product to use to put onto an old plywood floor? the wood itself is cracking and buckling from water damage (spilled water from plants),and I'm trying to help my dad get my grandmother's house prepped for sale.

What is the cheapest product you have used that you like the results on?

What is the average coverage amount of basic application of any of these products?

(I'm helping my dad prepare my grandmother's house for sale, to offset the costs of her assisted living facility. The budget pretty much doesn't exist, meaning as cheaply as possible. The room is approximately 12 by 16, but it could be as much as 16 by 16. there's still furniture in the way, so I can't get accurate measurements.)

[AceHoleInOne]

What are your plans for the plywood...what is the thought process...seal and cover with carpet, paint or stain, is there odor in the wood?

-Ace-

[jHop]

normally, it would not matter, as it's the subfloor of the room. However, the money is just not there to put another floor over it. Currently, the thought process is to get it acceptable for showing prospective buyers, but obviously not finished, so the new owners can cover the floor however they'd like.

when I say obviously not finished, I'm not meaning bare plywood, but no carpet or padding or tiles set down. There isn't any odor, but there are other issues in the room. We probably will just end up with a paint or primer over the plywood, but the plywood needs gaps filled between sheets and on the plywood itself.

I should probably mention it was once a porch that was enclosed over the course of just a few weeks. The problems include drywall work that is showing it's age, a potential leak where the two roof planes meet, a door that does not completely fill the opening, a door that is plumb and level but the door frame is not, a HUGE (really really big) sliding glass door that was never removed when the porch was enclosed in the first place, and the list goes on. And this is just one room in the house; every room needs a lot of work. Tomorrow, I'm supposed to be helping chip out mortar in the exterior bricks and do some tuck-pointing around two thirds of the house; the last third needs to be completed after the handicap access ramp is removed, so we can move the air conditioner. Nobody knows when the ramp will be removed, as it was installed by a third party on a temporary loan ... three years ago...

[PaulMarcel]

Is the ply nailed to joists of sorts? as in the supporting structure of the porch. Maybe you can remove that sheet and put a new one in. Normally subfloor ply is tongue and groove so you wouldn't be able to engage those joints, but you could put some scrap wood underneath the joint and drive screws in to the wood from above to keep the old and new sheets flush.

A picture would help, actually.

If you can flatten any of the bulges with an aggressive sander, you could fill all the cracks, voids, holes, etc with body filler. While doing flooring last week, I saw that there was some used in a number of places on a new home build.

[jHop]

Is the ply nailed to joists of sorts? as in the supporting structure of the porch. Maybe you can remove that sheet and put a new one in. Normally subfloor ply is tongue and groove so you wouldn't be able to engage those joints, but you could put some scrap wood underneath the joint and drive screws in to the wood from above to keep the old and new sheets flush.

A picture would help, actually.

Unfortunately, I don't have a digital camera, so I cannot show what the images I see are. The ply is nailed down to the floor joists. I think the joists are 2x6, but don't quote me. The joists have not been seen since the flooring was put down, maybe 20 years ago... These were basic panels of ply, and are not tongue and groove. There are some gaps up to 1/2 inch between the sheets.

If you can flatten any of the bulges with an aggressive sander, you could fill all the cracks, voids, holes, etc with body filler. While doing flooring last week, I saw that there was some used in a number of places on a new home build.

There are not really any "bulges," but there are some ripples. My concern is more that the top layer of the ply looks more like lace and 40 year old newspaper than plywood.

What about using shellac? perhaps a one pound cut, thinned out fifty percent? as a base coat? and can someone put thinset or mortar over shellac? Or is shellac the wrong material to attempt to fill gaps and put a "new face" on plywood with?

[AceHoleInOne]

Here is a thought...what about using a plywood floor patch for the gaps. Then coat the floor with a good sand paint. Sand paint should help fill or cover and distract the eye of any smallish imperfections. Try doing a few Google searches on the best paint for floors, then I believe, you just add sand?

-Ace-