Tiling concrete floor with plywood around radiator pipes

Hi

Apologies for what i'm sure is a pretty obvious question:

I'm about to do my second ever tiling job - the kitchen of our new-ish build flat (built 2002).

On taking up the old vinyl tiles I found that the floor around the radiator pipes is plywood - level with the concrete. Each piece of wood is about 10cm x 25cm.

A picture of the floor is below...

The tiles are large format porcelain (1200x600mm) and, on the advice of BAL I'd bought Bal Stone & Tile PTB to use as adhesive.

I've had a number of conflicting bits of advice for how to handle the different surfaces:

1. BAL technical advice said I'd need an expansion joint and probably Ditra matting.

2. Topps Tiles said I wouldn't need any Ditra matting or expansion joint - that it was fine just to tile directly over the wood because I'm using a flexible adhesive.

3. Another tiling shop (from which I'm buying the tiles) said I wouldn't need Ditra mat but would need Bal Admix AD1 at a 1:3 ratio for the wooden section.

4. Schluter said I'd need Ditra matting through the whole kitchne.

Any advice? I'm planning to prime the floor after clearing the glue properly with SBR primer. The kitchen is approx 3m x 4m in size.

Really would appreciate your expert guidance!

You would be best advised to remove all the vinyl sheeting and determine if you are going to tile to the skirtings or under them - because now would be the best time to remove them.

Note that tiling can trap your appliances in their below the w/t positions unless they have room to lift or have wind down legs.

The floor is dark to the left of the rad - is that damp?
Is there any damp anywhere on or in the floor?
You could split the ply and fill in with a semi-dry sand and cement mix - but first wrap the rad pipes to allow for expansion and contraction.

I take it that the whole kitchen slab is one piece of concrete?

You have disturbed some SLC but its no big deal - see what you have when the whole floor is cleaned/vacuumed and exposed.

Depending on any damp issues you will be good to tile straight over the concrete and any firmly fixed SLC. SBR primer is fine.

Using such large format tiles in only your second tile job is unfortunate - use a 1/2" round notch steel trowel, and use adhesive on the floor and butter the back of the tile as you lay it.
Lipping is a difficulty with large tiles. You could buy a Tile Levelling or Lippage System but for one floor it might be expensive - check it out?

Hire a tile saw - practice on any old tile.

Dry fit your lay-out, and then snap chalk lines or straight edge marked lines, & work to them.

Hi Ree

Thank you so much for your reply. Really is much appreciated.

The whole kitchen slab is one piece of concrete.

There's no damp - it's just that some of the glue underneath the vinyl was black. The rest was orange. The area around the radiator is black but is being chipped off (very slowly!).

Apologies for my noobness - not 100% what SLC is?

I'm intending to take out the skirting and remove the appliances before starting to tile.

Do you think it's absolutely necessary to fill in the the area covered by ply? Would it be okay to treat with the Bal Admix AD1 as I was recommended by the tiling shop?

The Lippage System looks great! Will definitely consider it and thanks for the recommendation!

Thanks again for your help - really am very grateful.

google slc

leave it in then. The bal admix is an additive for the adhesive nothing to do with wood.

Thanks again - so you'd think the Bal Admix is just a random suggestion and I should just ignore?

I've also been recommended to put portions of Mapetex membrane over the wood only (recommendation #5)! Do you think this is wise/necessary?

Thanks again for your help.....