Subfloor question

[ashevillian]

So, I've demoed my bathroom and I am about rebuild. Some of the original subfloor was missing when I removed the old t&g hardwoods. So, do I rip all the diagonal subfloor up or put new subfloor on top? I'm a bit worried about removing the subfloor from a structural point of view. The span below is about 10' and I've sistered all the old 2x8s below.

We're putting hardie backer and tile down.

Thanks!
I can post a pic later

[SkipW]

Do you have the height to add another 3/4" to the floor? If so, in my perspective, it can't hurt to add rigidity to the floor especially for tile, as 2x8 is not so hot for framing in a 10' span in my mind.

I'd probably fill in the missing parts of the existing, then top with 3/4 ply and then lay your floor (hardie and tile). Or if you have existing good solid 3/4 or 1" subfloor, you could use 1/2" ply to lessen the height change.

Last option, of course is if the existing subfloor is pefectly solid and you have no deflection in the framing, you could go hardie and tile right over it....

I asked more questions than I answered, didn't I?

Others will have opinions I'm sure....;-}

[ashevillian]

Here is a picture.

You can see where the missing subfloor is and the new 'sisters' below. I am keeping the original 3/4" hardwoods in the surrounding hallway. I suppose repairing the subfloor (with salvaged subfloor/sheathing from other areas in the house) then adding 3/4" t&g plywood on top followed by the 1/4" hardie board and tile would only put be at 1/2"-7/8" higher than the existing hardwoods. That's doable with a marble threshold or similar.

As a side note, I removed the walls to the bathroom due to a combination of rot, previous plumber/electrician hacks, and studs that varied from 3 7/8"-4 1/2". We are tiling the floors and subway tile walls so nice square and plumb walls are essential.

[phil]

I'd just replace the missing subfloor bits and use some reclaimed flooring. or use thinner flooring. having a transition in the flooring height is possible but will always look like the result of a reno and at this point you couldn't really be down to the bones any more than you are now. Is there no other way? you have 3/4 to play with. 5/8ths ply and sheet flooring or cork or something? stubbed toes are a really common injury.