Ok so we are renovating our 1954 mid century modern home and new floors, doors and a kitchen are the first on the list. Here is the issue...so we have 3/4 2.25 oak flooring in 2 of our bedrooms that is laid on top of 1x6 fir laid 45 to the joist. The rest of our place has 5/8 ply on top of the fir 1x6s... So my plan was to rip out the 5/8 ply ‘and install our new 4.25" white oak in the rest of the home, but after after we got the material home we decided to lay it in our whole place. The problem is that the ply wood is going to be a nightmare to remove. It was installed with spiral nails and the heads shear off before the nail will budge. also the heads will pull through if you try to pry the ply so I am planning to install the hardwood over the 1x6 / 5/8 ply subfloor. Do you see any issue with this? I am replacing all the doors and jams so i can hold the new ones up so thats not a concern. Also I was planning to rip out the old 3/4 hardwood and install osb or ply so that all the floors are even steven, unless I can go over my hardwood? Any ideas on JUST how big of a no no this is?

Thanks
Larry in Michigan

YES, you can lay right over the old flooring. Just make sure the seems dont line up. Make sure the old flooring is flat. Good luck

On older homes where the systems have just been nailed, I'd double check for squeaks and re-nail where needed prior to installing any hardwood flooring. Since you are going replace the old 3/4" strip in the bedrooms, just remove it and install new 5/8" ply to match up in height to your existing 1 x 6/plywood substrate. Then you should have a even, very solid and flat subfloor to install your new hardwood over. Since you are remodeling much of the home's fixtures, door and appliance clearance should not matter. It's possible the standard 6' 8" door may be a little too long and need to be trimmed but hopefully not. Same for the exterior doors.

Thanks for the reply... Its a tuff call as I know that the proper method would be to rip out the 400 sq ft of old 2 1/4" but the thought of saving a few hours and a few $$$ would be nice That being said I might sleep better knowing that I installed the 5/8 board and its all the same... I had thought about door and will measure to see how that will fit... We had planned to install full height doors, but have yet to get to that point.

Thanks
Larry

Remove the hardwood and replace it with appropriate plywood.
Refasten all existing plywood as well to make sure all is secure.