Hi there - we're laying solid 3/4 prefinished hardwood and I have a question on proper fastener size. We've got a diagonal 1x6 T&G subfloor, are adding in some shingles (no more than 2 thick) to fill in a valley running in the center of the room (joist sag, old house), then on top of the shingles we are adding a layer of 1/2" plywood.

So over the shingles and 1/2 ply, will the standard 2" nails or staples still work? I'm concerned that the floor won't be secure and tight over the shingled areas-

Thanks!

That's a mountain of shingles. I would screw and glue plywood instead...

Darn, I had heard that two shingles thick would be ok. Can you get 1/8" plywood?

Sorry - re-read my first post and think it might have been confusing- just to clarify, we're doing two layers of shingles, not 2 inches deep of shingles.. Does that change anything?

Two layers sounds reasonable to me, beats 2 inches.

so, no concerns then about getting a good tight fit using the 2" nails over the shingled areas then?

No concerns...Yea...I bout fell out of my chair when I thought 2"

Just be sure that the 1/2" ply over the top is nice and tight.

( Yes, you can get 1/8" veneer...but you can also go 5/8" ply, instead of 1/2 )

That's great - phew! Sorry for the confusion and thanks!!!