What are your subfloor dimensions...aka what's the right dimensions for replacements?

[SmellyHouse]

All THD,

Since I am couchbound, I thought I'd do some research on a replacement subfloor for the first floor. I have a 20x22 foot building envelope, joists are 2x8, 16" (c to c) span between joists, with a slightly undersized (and cracking) main support beam (which I intend to shore up with plenty of support posts on cement pads when the fun begins...at least 4, if not 6 of them). At this point, I can't tell if I have balloon framing, the house was built in 1928 and is only 1.5 stories, so there is a good chance it is.

I want to replace the subfloor on the first floor (it's undersized Advantek that a 2nd rate contractor used to replace SmellySubFloor). I'd like to get enough to replace the entire house, in case SmellyRescue cannot salvage the 2nd floor subfloor from the cat carnival that occurred during the previous owners' reign.

The original subfloor on the 2nd floor is 6x10x0.5, which seems a bit thin. I have only 2 doors on the 2nd floor, and 2 exterior doors on the first floor) (both of which I wanted to replace anyways) that need to be taken into account.

Is 1/2" vintage lumber thick enough? Or should I be looking at 3/4 to 1 inch?

TIA.

[Mick_VT]

Personally i would use the T&G plywood that they sell specifically for sub-flooring at most lumber yards. they sell OSB for this too, I just prefer ply

[SmellyHouse]

Thanks Mick.

If I did plywood, I'd use 1 inch marine grade, because I do not want knots. Reading Fine Homebuilding and other professional building forums have led me to believe that even plywood quality, these days, has plummeted (hence the rise of Advantek, which is glorified OSB). I would not put down OSB if someone paid me to...and why I want it the heck out of my house (and why I'm ticked at myself that I let the contractor talk me into keeping it). 50 year warranties are just crap...when we know solid dimensional lumber can last 200+ years if cared for properly.

And, for the price of marine grade plywood, I might as well consider dimensional lumber....at least that's my thinking.

[Gothichome]

Smellyhouse, I think it comes down to what you want in the end. Tongue and groove ply as Mick suggests has been my go too for this sort of thing. Are you thinking of lifting the current sub floor bringing you back to the joists, you will have a half inch, min. code here is 5/8. But this is for sub floor only, if you have the clearance at the doors and the walls replace with 1 inch. Depending on what you planning for a final floor height 3/4 should be fine as a minimum. If you looking for a fine stained floor yes you might as well go strait to tongue and groove boards in your desired hard wood.

[SmellyHouse]

GC, this would be subfloor only. HWF would go over.

[Gothichome]

Smelly, then I think 3/4 tongue and grove ply would be fine. Doesn't have to be the expensive knot free stuff. Your hardwood are you thinking 3/4 tongue and grove. If so, that'll give a full inch and a half night. Do you have the room from the joists to fit that?

[Gothichome]

If not, you may want to consider going 5/8 ply, you can get pre finished hardwood tongue and grove in 3/8, this will get a full inch. Only 1/2 inch higher than your current smelly floor.

[SmellyHouse]

Do you have the room from the joists to fit that?

GC, what do you mean here? Are you referring to how the subfloor would slide under the existing base molding? If I wanted to do that, I would need the existing depth of 1/2"...which isn't up to current code

I did find 1k sq ft of 1/2" dimensional lumber at an architectural salvage place, though it is insanely overpriced.

[Mick_VT]

This

http://www.homedepot.com/p/23-32-in-x-4 ... /100003769

Is all that is needed 1" marine ply is unnecessarily over and above

[Olson185]

I use 3/4" B/C plywood (T&G not practical in most cases because of trimming) and made sure all seems rested on FJ centerlines, 2x6 FJ blocking, or overlapped the rim joists. The plywood is glued n' screwed.

Baseboards should be removed unless:
1) they were installed before plaster n' lathe,
2) they're brittle,
3) they're not painted and one doesn't want to disturb existing seams of the finish,
4) it would be impractical for some reason (ie. expense),
5) it would be easier to sister FJ blocking at the rim joist which sub-floor and finished floor can't reach because of baseboard being in the way).

However, shoe molding should always be removed, regardless, so sub-floor and finished flooring can be installed and shoe molding reinstalled, after sanding and finishing, so shoe molding will rest on the new finished floor; not beside or beneath it.