Wood floor - float or plywood?

Want to lay solid oak on a floor thats part newish concrete, part old floorboards. I have a few questions:

- Can anyone advise if its best to float it or lay on plywood as we're getting conflicting advice.

- What exactly is floating, does it make the floor more noisy?

- There may also be moisture issues with the concrete floor so maybe we need some kind of moisture barrier?

I've checked key posts and this isn't really covered. Thanks.

You'll always need a moisture or vapour barrier when laying timber floors over any concrete- regardless of how old or dry that concrete substrate may appear. Laying a floating floor on plywood would seem like a very good approach when you have both timber and concrete substrate. Once you incorporate a sound resilient layer like Regipol you shouldn't have any concerns regarding sound. I know this topic has been covered in considerable detail elsewhere.

Thanks Carpenter, I can't find more detail here anywhere, I've read keyposts. So you think floating it on plywood is the right approach? Thanks.

Our carpenter told us to float our timber floors - solid oak - new build. His reasons for it was that if we used glue and put it straight down, if we ever needed to take it up it would be messy, timber would be ruined etc. The other reason he gave was that floating it would be cheaper as the glue used in, shall we saying "sticking it to the floor" works out a lot more expensive. He is putting some underlay or whatever underneath the plywood and as we are running it throughout the house has advised that we put saddles in all the doorways to allow for expansion, he is having oak saddles made up. Hope that helps a bit

Aimee has covered the essential points there I think.

Thanks Aimee and Carpenter. Sorry if I seem thick but I'm confused now, it sounds like you're saying its meant to be floated on plywood. Does that mean nailing it to plywood?

If I understand our builder hes saying the options are sticking it to plywood or "floating it" by not using plywood at all and putting down a foam layer and sticking the wood to that. Help!

Toby - don't float the wooden floors - floating usually means laying the wood on a vapour barrier (ie thin foam sheeting) and nailing / gluing to concrete floor. Laying on plywood means nailing / glueing a 2cm think sheet of ply to the floor and then laying the wooden floor on the ply.

A solid wooden floor floated over concrete, particularly new concrete, will warp and crack eventually as the concrete drys out and the boards shift. Floors laid on a ply base will not warp as easily as there is more flexibility in the ply to move and adjust to the changes in moisture and temperature.

I have had wooden floors floated and laid on ply, exact same board from the same manufacturer and both in new builds - the boards which were floated over concrete started to warp after two years whereas the boards laid on ply have been perfect.

Floating means glueing the tounges and grooves of each plank to the adjoining ones. A floating floor is not attached to the sub-floor by any means, hence it floats in position!
Leo

Floating means glueing the tounges and grooves of each plank to the adjoining ones. A floating floor is not attached to the sub-floor by any means, hence it floats in position!

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Thanks for clarifiying that - now that you say it it makes sense!

Toby,

Besides the key posts you may find some other info. in these threads.