Advice Needed on Building out Wall Depth? - Tile Advice

[kcdionysus]

Hi all

I've been asked to completely refurbish the in-laws bathroom and they've taken it on themselves to do the donkey work of removing tiles, wall coverings etc. in preparation.

Anyway, the walls were tiled lower down all the way round and papered/texture coated above. When they've removed the tiles, the section of wall behind the tiles are proud compared to the papered section of wall above by 6-7mm. I'm guessing here that the walls were tiled with a sand and cement adhesive in the past and this is what this is. It has since been gone over with a more conventional addy and new tiles? I chiselled off a section of the proud element and it's not coming off cleanly as it's really stuck to the render coat underneath. I've added some pics to help show what's going on.

What would you guys do to level the walls for completely tiling over?

 

[Rick-o]

I would use a tile backer board to bring out the top half of the room, either level with the bottom or board the whole lot using 2 different size boards

 

[kcdionysus]

Thanks for the reply. You've echoed my initial thought to be honest but I wanted someone to either validate my thinking or perhaps offer a different solution before I went ahead. I've used Marmox boards a lot in the past as well as cement boards but these have all been on stud walls.

I've always used 12mm for general use so do I need to take anything else into consideration to put up 6mm (probably Marmox or Wedi) boards? Would you just mechanically fix the boards up or add some kind of bed to the back as well?

 

[Time's Ran Out]

Mechanical and adhesive fix 6mm Hardie tile backer boards to top half. Make sure you get the emulsion off. Tape the joins and your good to go.

 

[kcdionysus]

Do I need to do anything to the render layer before tiling over? It's flat, dry and has been tiled over before so has some remanents of old adhesive on it so does it need a primer or sealer first?

 

[Time's Ran Out]

Grind off all lumps, sand it down and get rid of dust with damp sponge. Best use a cement based bag adhesive - see top choices in on going poll.

 

[kcdionysus]

Thanks for your help. I pretty much always use Mapei by choice but the guy I do a lot work for brings random gear in and some awful ready mixed tub stuff for kitchens that a day later is still soft and pliable.