Slate Tiles in Kitchen and Bathroom (floors and walls)

[loutuckett]

We're having our kitchen and bathroom re-done in a few weeks, and want to put slate tiles on the floors and on the walls in the shower enclosure. I've been reading online about what ply, adhesive etc is needed, but seem to keep reading different things. So your professional advice would be much appreciated!

The tiles are 10mm thick and are gauged (but not calibrated). In both rooms they will be laid onto floorboards (with ply or whatever is appropriate in between). Obviously for the tiles on the walls these will be going onto newly plastered walls.

Advice on the following would be great:
1) When to seal the slates (particularly in the bathroom) - I've read that before and after grouting is important to seal properly
2) What ply/other material should be laid on top of the floorboards to put the tiles on? The builder has quoted for 4mm external ply. Is this sufficient?
3) Will normal plastered walls take the weight of natural slate or do we need to sand and cement them? (I read somewhere we might!).

Thank you!
louise

 

[mikethetile]

Hi louise

its better not to plaster the wall before sticking slate, what is the finish now

4mm overply is totally inadequate and a waste of time you need 15mm wbp ply as a minimum, 18mm is the nearest size

your builder is a duffer dont let him tile for you as he obviously has no experiance of tiling let alone fixing slate

get a reccomended tiler from here to quote you for the job, shower enclosures , fixing to suspended wood floors and fixing slate are all specialist work

 

[kilty55]

4mm ply for floors? dont let him in your home to tile anything

also plaster skim finish will not be strong enought o hold heavy slate imo,have the walls already been plastered loutucket?

 

[loutuckett]

Thanks Mike, I was worried that 4mm ply wasn't enough. The problem with using 15mm ply is that the floor will then be significantly raised from the hallway, but I'd rather have a small step up than a ruined floor! The reason I said it'll be a newly plastered wall is because it'll be a new stud wall, so I'm guessing that'll be freshly plastered. THanks again for your help, louise

 

[kilty55]

hi lou,plasterboard is stronger then skim finish,also if your concerned about height you may be able to use a 6mm cement board

 

[doug boardley]

top advice from the above posts Louise ^^^^ If I was you, I'd be putting something like hardibacker 500 (cement board) on your stud walls. These will bear the weight of the slate.

 

[Ken Bruty]

Hi Louise,

Regarding the height issue, I would recommend ripping up the floorboards, and replacing the floor with 18mm wbp ply screwed to the joists at 300mm centres and noggings added if there is any flex in the floor, prime the ply with acrylic primer on the underside and edges, but not necessarily the top face unless the adhesive manufacturer recommends it. This will bring the floor to 4mm lower than the original height assuming the floorboards are 22ish mm. Then you can get ditra matting or dural ci matting to (name 2 brands) stuck to the plywood and that's giving your total floor thickness of approx the same as your original floorboards were, so no height issues with the subfloor. Then all you have to think about is the thickness of your slate on top, which is fixed to the matting directly.