tiling on floating wood floor

Hi all,

I am going to lay travertine tiles in my hall and kitchen.
The hall and a small part of the kitchen has a floating wood floor. The portion of the kitchen with the wood floor is about 3m X 2m, the rest is a concrete extension. I plan to lay the tiles over the whole kitchen.
I have read in a diy book that 1/2 inch plywood needs to be layed first to strengthen the wood floor.

Is 1/2 inch plywood really necessary, would a 1/4 inch do? (cheaper and easier to lay)?
The tiles are stone and are porous. Do I have to use a special tile cement that will not stain the face side up of the tile i.e. soak through?
I plan to lay them with a very small space between i.e. < 3mm. Is there anything special I need to be aware of doing this?

any advice appreaciated,

thanks,

Brian

What do you mean by floating floor? You would need a very solid base for all tiling. You need to minimise the amount movement in the timber. Im no tiling expert but i would think for travertine a screed would be a better base. I would go for the 1/2 board over the 1/4 inch, which would give no strenght at all. Its not much dearer or easier to lay. the tiles will have to be sealed i sure if you search some threads here you will get some details

When you say a floating floor I presume you mean regular floorboards sitting on wooden joists. If this is the case then I would first look at this portion of the room and do a bit of bounching around to ensure there is not alot of movement in the floor i.e. the joists are solid. If there is a bit too much movement cut the flooboards in that area and wedge blocks of wood or some other support under the joist.

Once the sub-floor is solid enough, then 6mm or 9mm plywood will do the job. Use whatever you need to keep it level with the concrete side of the floor or else use levelling compound to bring the concrete side level with the wooden side.

I would then use a flexible adhesive on the wooden part and you could also use this on the concrete side.

I did this work in a house with 3 different levels, 2 wood sides and 1 concrete and it worked out great. I'm sure others will have some other ideas/methods also.

You'll need to either fix or remove the floating floor, there will be too much movement. Replace it with ply of the same thickness to bring it level with the concrete.
Leo

Leo said:

Replace it with ply of the same thickness to bring it level with the concrete.
Leo

Click to expand...

...and if there's joins in the ply you should put the 1/2 inch sheets of ply on top of this new ply at right angles to the new ply to pervent any movement between sheets cracking the tiles. Try to have as few joins in the thin ply as possible

Hi All,

On the same topic.

Got a tiler out to price new house ensuite & Bathroom.
He said that the ply is nailed to the joists and that I should screw then also to prevent movement down the line .

Is this true ?
Are there any special screws for using with Ply
or would a standard 40 mm screw do the job ?

Thanks,
Wolverine.

Wolverine said:

...He said that the ply is nailed to the joists and that I should screw then also to prevent movement down the line .

Is this true ?
Are there any special screws for using with Ply
or would a standard 40 mm screw do the job ?

Thanks,
Wolverine.

Click to expand...

Yep, it's true. Natural movement in the joists will eventually loosen the nails. Screws won't suffer that problem. If you're putting down 1/2 inch ply, with 40mil screws you'll only get 15 mil into to joist, I'd go with 60 mil at least.
Leo

I used 40mm to fix 9mm ply onto floorboards (every 6 inches). Not sure what a floating floor is in the context of a sub floor. Only floating floors I've come across are laminate?
Adhesive is about twice the price for fixing to the ply rather than concrete, the supplier should be able to advise about soaking through ? never heard of that.

A floating floor is one which isn't physically attached to whatever is underneath it.

Hi all,

thanks for your replies.
What i meant by a floating floor is just a norm wooden floor nailed to joists underneath. After reading the advice on this page and on a few other posts, here's the plan.

- do bounce test of floor and strethen underneath with blocks if required
- replace loose existing floor boards (only one or two)
- lay 9mm plywood and screw it with 40mm screws (or is 6mm enough)
- put a coat of polybond on plywood
- use flexible floor adhesive on plywood
- use concrete adhesive over concrete as it will be easier to enable leveling (should only be a few mm out if I use 9mm plywood.

does this cover all the angles

Brian,

I would use levelling compound on the concrete to bring it up level with the plywood if its a couple of mill lower.

Also, regarding scewing the plywood down, I have heard that some tilers are using 2" nails that have a ribbed section along the shaft. They grip the wood better than regular smooth nails and so should not come loose. I used these myself on a small upstairs bathroom and its seems fine, although it could take some time before problems present themselves but so far so good. The advantages of using these nails is that it is quicker and also in the event of ever needing to pull it up, the ply will come up much easier than if it was done completely with screws.

Anybody else out there seen these nails being used?

They're ring-shank nails. As you mention, the quick option, but not always the best.

will do with the screws. am doing job starting tommorrow, will let you know how it goes (if anyone is interested that is!!)

thanks,

brian.

I wouldn't use ring shank nails myself, pounding them in will damage any plasterboard ceiling below. You could do a lot worse than screwing your ply down with black phosphate, bugle head drylining screws. They're strong, come in various lengths and are cheap.