I've pulled up loads of subfloor (see: kitchen rebuild thread). It may be more cost effective to go at it from below though - 3/4" tongue and groove plywood runs in the low $30s/sheet.

Thanks schicksal- please excuse my lack of knowledge here.
Can the pulled up ply wood cannot be reinstalled?

thanks!

Scrappy, if the plywood is in good shape there's no reason not to re-use it. But it will serve as the base upon which everything is built, so if it is worn, let it go.

thanks EAM. If the plywood can be mostly reused, would it be easier/more cost efficient to pull up the wood subfloor to install utilities rather than fighting with passing them through the joists via holes in the basement ceiling? Obviously if we find underlying damage, I'd rather get the boards replaced and all damage fixed before we proceed.

schicksal, I looked at your rebuild thread- wowsa! I am bowing to you for the work that you have done in resurrecting your home. It is a good thing that you discovered that before your floor caved in or you got seriously sick from the mold!

The plywood subfloor extends under the walls and cabinets. It has a tongue and groove at the edges and the ends always fall on joists. If you remove it you will have to cut it at the walls and cabinets and when you reinstall there will be no tongue and groove at those areas. You will have flooring issues due to movement there.

Thanks kevdp4, the kitchen is being gutted so no cabinets.

I have been reviewing subfloor repair videos on youtube and it seems like it is really hard to remove in one piece as I had envisioned since it is usually glued and fastened with nails or screws.

That said, it seems like a subfloor repair is not uncommonly needed. Would cutting the subfloor along the middle of the joists (thus allowing the new subfloor to be nailed or screwed to the joist) and adding 2x4's perpendicular to the joists to provide the perpendicular nailing surfaces stabilize the nre subfloor sufficiently?

My house was built in 1979, would tongue and groove subfloor have existed then?

thanks!

I would much rather replace a drywall ceiling than subfloor; it is much easier and safer to remove and replace and much less expensive than subfloor. You're going to be making the same joist alterations whether from top or bottom.

It is not cost-effective to expect to recycle the subfloor, especially if it was installed with construction adhesive and ring shank nails, which was very possible in 1979.

The only exception would be if the floor is substantially out of level, say, 1" over 12'.

Wouldn't it be easier & cheaper to rip out & repair the drywall ceiling in the basement than the subfloor in the kitchen? Also consider that it's difficult and sorta dangerous to work in a space without subfloor. It would really suck, for example, if someone fell through the floor into the basement, in which case you'd have to repair the floor, ceiling, and person that fell.

Also wondering if you need insulation in the floor since it separates two finished, environmentally controlled, spaces - I'm guessing it's for sound attenuation? Some folks claim that insulation like this helps a lot with sound attenuation, but the scientific studies that I was able to find suggested that it doesn't provide significant benefit.

Hi GauchoGordo, thanks for your thoughts.

The insulation is needed only in the 2 foot bumpout that runs the length of the kitchen and eating area, we can't get at that from below due to the existing exterior deck which is only 2 feet off the ground. I was thinking that since the kitchen would be gutted, this would be an opportune time to get some insulation in there from above, and at the same time run utilities while the subfloor was up.

Thanks to everybody for their help, I think that I have enough information now to ask about this possibility from the contractors I will eventually choose to bid on my project.

I would think that you would have access to the cantilevered portion from below. If that is the case, you can insulate that area after the ceiling is pulled down.