Advice on laying travertine tiles on part concrete/ part wooden floor

[Speppin]

Apologies if this has already been answered as I know there is lots of info on plywood floors here, but think our situation is unique.

We've got a kitchen that is part concrete floor, part wooden, and a small section of brick (where an old stove once sat). We would like to lay travertine tiles on top and looking for advice on how best to prepare the floor.

Ideally we'd like to replace the floorboards above the joists with 18mm plywood, as this would make the plywood part level with the concrete/brick parts of the floor, and ensure the floor is not raised any more than the thickness of the tiles. Another possibility is to lay 25mm plywood on the joists and 6mm plywood everywhere else.

A flooring specialist recommended leaving the floorboards on, and covering the entire floor with 18mm plywood before tiling. While I've no doubt this is a great solution, we would rather not to have to raise the level of the floor by that much if at all possible.

Anyone know if we can get away with screwing 18 or 25mm plywood directly onto the joists? Also, will the boundary between the concrete part of the floor and wooden part require special attention?

Thanks in advance,

Stephen

 

[Gazzer]

If you were planning to remove existing boards and replace then i would go for the 25mm option with a 6mm tile backer board over the concrete part to get the level.
While the old floor was up I would strengthen the existing joists in any way possible. Extra noggins is one way or laminating each joist with 18mm ply glued and screwed would strengthen it a lot.
The final test would be when all ply was laid would be to test for any deflection/bounce in the floor.

 

[Speppin]

Just after writing found another post which seems to suggest we can get away with laying 18mm WBP ply direct onto the joists with noggins added, and using a good quality flexible adhesive, with an expansion gap /expansion joints between the wooden and concrete parts:

http://www.tilersforums.com/guest-area/13637-tiling-part-concrete-part-t-g.html

If don't hear anything to contrary we'll go with that!

 

[Gazzer]

I would also opt for an expansion joint through the tiles where the 2 surfaces meet.

 

[Speppin]

Wow, thanks Sir Ramic, fast response! Will take your advice to glue and screw the ply to the joists as well as noggins. How to test bounce in the floor - just by walking on it? Also a question hadn't thought of earlier - is there a minimum distance btwn joists? I think ours are 400mm apart, but some are a bit farther.

 

[Gazzer]

Wow, thanks Sir Ramic, fast response! Will take your advice to glue and screw the ply to the joists as well as noggins. How to test bounce in the floor - just by walking on it? Also a question hadn't thought of earlier - is there a minimum distance btwn joists? I think ours are 400mm apart, but some are a bit farther.

maybe I didnt explain the strengthening the joists well enough but this may help http://www.tilersforums.com/tile-ad...ration/39212-another-way-debounce-floors.html
As for the distance between joist If you use the method explained then you should be fine.
Testing for bounce, Fill a glass of water to the brim and place in the centre of the floor then walk around the glass about 1 metre away. If any water spills you have bounce. Its hard to explain and that method would vary depending on the size of the person walking around the glass. basically if you can feel or see movement while walking or standing on the floor it is not strong enough.

 

[david campbell]

i would also use ditra matting if the floor is a large are with travertine

 

[Speppin]

Sir Ramic - ah I get now what you meant about the 18mm glue and screw. That is a nice method

David Campbell - thanks for your suggestion, hadn't heard of ditra matting. The floor is roughly 6m x 4m, if we use ditra matting can we forgo the expansion joints? Could we get away with something like mapei keraquick + latex for our floor size?

 

[Gazzer]

The method for the joists is very good as if the floor ( as in the original joists) is out of level you can level it all up by use of this method too.

Many people use Ditra especially with stone like Travertine. Its great stuff but for lateral movement and not to be confused with adding strength. You will still need an expansion where 2 differing substrates meet IMO.

Keraquick and Latex is seriously good stuff.