Best Underlayment

jscozz

I have read through some other threads on here about fixing existing underlayment... even one referring to particle board as the underlayment of choice in the 70's/80's. I remember my dad building our house and all rooms got 3/4 plywood subfloor and 5/8 high density particle board glued on top of the subfloor before carpet was laid. Even joints patched up with plaster (I think it was plaster).

Now I am finishing my own home... all subfloors are 3/4 T&G plywood over TJI joists 16" OC, glued to the joists. So, my question comes down to... what is the best possible underlayment these days under the following floors:

1) Unfinished 3/4" hardwood: I am planning on having this laid directly on the 3/4 ply subfloor.

2) Tile: I am laying another layer of 5/8" plywood, perp to joists, offset from subfloor by 2' in the short direction and 3'-8" in the short direction, so end joints are 4" offset from the joists, screwed through subfloor below and not into the joists and also with LiquidNails subfloor adhesive between. Then Ditra thinset to plywood and tile thinset to Ditra.

3) Vinyl sheet/tile: Is particle board still proper to use here? How about in bathroom or laundry room?

4) Carpet: OK... Do I go with the good old 5/8" high density particle board, glued to the subfloor or something else? Either way, what kind of glue do I use and should it be laid like the plywood under tile having end joints offset from the joists by 4"?

Any advice or links to the current BEST practice in these 4 cases to let me know if I am on the right track would be greatly appreciated. I am not looking to just get by and meet code here... I am willing to spend money to have the best possible solution.

My goals are solid, squeek free and long lasting floor system throughout the house.

Jeff