Can you install natural timber flooring over Formply?

[PTB]

I have an old house built in the 50’s.

The current timber floor is not level. It varies in height up to 25mm.

In a years time we have plans to knock the front of the house off to extend and build a balcony.

The back end of this same level is to have a kitchen installed ASAP.

I want to level the timber floor in the kitchen area and build the kitchen now.

The family and I also have to live in this while I’m doing this work.

I am thinking I could take up a section of the floor level the joists, then lay a sheet of some product like formply, repeating until I’ve got an area big enough for the kitchen.

I was then going to build the kitchen on top of the formply.

Then level the rest of the floor in the same fashion with the formply sheets.

Later when the extension (I’m a year or two away from getting to this job) is done I would lay the natural timber floor over the top of the formply.

I’d have to factor in the height of the natural timber flooring when figuring the kickboard height.

This level of the house is the top level, so I’m thinking this might also help with noise below.

Questions I have:

1. Would formply stay flat and straight/ resist cupping?
2. Will the natural timber floor I eventually install fix OK to the formply?
3. Is there a better product to use instead of formply?
4. Is there a better way?

Thanks in advance for any advice!

[PTB]

Thanks again Nailbag.

I hadn’t thought about how slippery Formply is.

 definitely go with the yellow tongue.

Great advice.

Pete