Kitchen floor advice

[ArthurTiall]

Currently in process of installing new kitchen. Plumber by trade with very little tiling experience.

I have kitchen/diner with the floor makeup being concrete in kitchen and suspended timber in dining room. Overall area approx 25m2. The plan is to use either porcelain or natural stone tiles (leaning towards porcelain) No exact sizes as of yet but probably going to be medium to large tiles.

Recommended by a friend who carries out tiling work regular that 6mm plywood is fine aslong as it's fixed down adequately. I carried out work screwing to timber boards and grip filled the sheets to concrete with additional screws to overcome any slight lips between sheets. After looking on the net for some levelling compound I've seen lots of advice against tiling on plywood and have since heard mixed reviews. The salesman at the local tile shop has strongly recommended I remove the boards on timber and replace with 'no more ply' boards and where these meet with the ply on the concrete (which is now most probably not going to come off) put a meter wide slither of some sort of what looked like foam sheeting. I understand Bonding to ply can be trickier but will it not work aslong as it's been primed correctly? And do I really need to replace the plywood sheets on timber floor with 'no more ply' sheets?

Any advice? Thanks

 

[Andy Allen]

Why on earth did you cover the concrete floor with 6mm ply..?

 

[ArthurTiall]

Why on earth did you cover the concrete floor with 6mm ply.

To make dining room level with kitchen

 

[Andy Allen]

I would rip it all up and start again...

Overboard the wooden floor with 6mm hardie backer boards or no more ply glued and screwed down.
Use self levelling compound to bring the concrete floor level or stick down 6mm insulation boards.
When you tile put an expansion joint where the concrete meets the wood.

 

[Old Mod]

Hi and welcome to the forum Arthur.
You've come on ALMOST in time.
The use of 6mm ply on any install is wrong for so many reasons.
British Standards states a minimum of 15mm ply for overboarding, but even that is dated and most pro tilers will steer clear of timber substrates at all costs.
They are just too prone to problems and failures.
And what was done 20 yrs ago is just not the same now, if for no other reason than that the ply available now, is just nowhere near the same quality.
What Andy has described above is a much better suited to your situation and will give you longevity in your install.

 

[Flintstone]

When you say suspended timber floor, is it joists under there or floating chipboard on insulation ?
Assuming its joists, my way to deal with it is to overboard the whole area with no more ply or hardie, stuck down with tile adhesive and on the wood side, screw it too. Personally if the timber is super solid and old I don't put an expansion joint in with porcelain tiles but you should, especially if it's a new floor / extension or it's showing any signs that there might be movement.

 

[Flintstone]

make sure you post again if you decide to put stone down as that requires more preperation. Really winds me up when people who think they can tile suggest 6mm ply

 

[ArthurTiall]

When you say suspended timber floor, is it joists under there or floating chipboard on insulation ?
Assuming its joists, my way to deal with it is to overboard the whole area with no more ply or hardie, stuck down with tile adhesive and on the wood side, screw it too. Personally if the timber is super solid and old I don't put an expansion joint in with porcelain tiles but you should, especially if it's a new floor / extension or it's showing any signs that there might be movement.

It's a 1950s built property, it's old school boards (not tongue and groove) on joists.
If I did put an expansion gap, how wide are we talking between either floor levelling compound and 'no more ply' or just doing the whole area in 'no more ply'?
It may be tricky to remove grip fill so may have to go down route of levelling compound for concrete side.
I see this 'no more ply' has its own range of screws and adhesive. I presume I can use other screws and adhesive?

Thanks guys, appreciating feedback

 

[Flintstone]

Use there glue and screws on the timber side if you are levelling over the concrete. Grip fill will come up easy from concrete. An expansion strip is like a trim that sits in a joint, there about 10mm wide, you can get various colours to help keep it subtle, no more ply has instructional videos if that helps

 

[hmtiling]

A soft joint would look better and don't think there's need for a mechanical expansion joint here. The soft joint can be a 3mm or so joint left free from grout and adhesive and filled with Silicon that matches the grout.
And we all know how good all plumbers are with Silicon