5/8" plywood subfloor for engineered hardwood--thick enough? and for a tile entry?

Hello,

This is my first post. I can't believe how active this forum is. We just bought our first home and . . . .
We're in the beginning stage of installing 1/2" (total thickness) engineered hardwood that we purchased in about 1,400 square feet of the home. Actually, we are still preparing the subfloor.
I found out today that the flooring manufacterer, and the NWFA (national wood flooring association) has 3/4" plywood or OSB subfloor as their minimum thickness. Our plywood subfloor is 5/8" on joists with 16" spacing.

Is our subfloor thick enough for the engineered hardwood we plan to install? Other than warranty compliance and NWFA compliance, what are the benefits of a thicker subfloor? We didn't budget time or money for subfloor replacement, but I'd like to understand if our subfloor is adequate before we lay 10K worth of hardwood over it.

Also, we are considering tile or stone in the entryway. What would this require in terms of subfloor?

Thanks so much to all of you People-of-the-world-who-stay-up-all-night-on-a-DIY-forum!

If the subfloor is substandard for the material, it will flex causing noises or distortion of the material. A wood floor may be resilient enough to move with the subfloor, but tile is inflexible, so it, or the grout joints, will crack and separate if there is movement.

Tile generallly is looking for about 1 14" subfloor thickness. 5/8 plywood or osb seems a little thin period, no matter what you put over it.

Thanks for the replies. Any other thoughts? For the tile, we can lay another layer on top of the subfloor, right? But then we'd have a transition down to the hardwood, if we don't change the 5/8" ply subfloor there. Also if we beef up the subfloor, would that be about replacing it totally or putting another layer of subfloor material on top of existing subfloor?

We are at crucial decision point in terms of subfloor, so thanks in advance for additional thoughts.

Sara

Normally you would place a stiffening layer on top and transition down.