wall tiling questions

G'day All,
I have a few questions regarding a planned ceramic mosaic kitchen splashback (I have never tiled before).

The wall was tiled previously and pulling the old (large) tiles off has revealed a wavy, uneven wall. How flat does the plaster have to be when using mosaics and what is the best way to achieve this (eg. Skim coat with an extra large applicator)?

Do I then apply a primer or a sealer to the plaster/skim coat or is it waterproofing compound, or are these the same thing?

How thick do I apply the glue and what do I apply it with?

The shape of the splashback is an 'upside-down T-shape' (rectangular if not for the overhead cupboards on each side in other words). Where do I start the tiling (ie. At the top or the bottom, the middle or one side etc)?

Any help would be appreciated.

Regards,
FishHead

G'day fishead
I guess the mosaics are on about 300x300 sheets? If the wall has gentle waves in it then you don't need to do anything with it - that is the joy of mosaics. Just make sure you don't have any lumps or divots that a little tile might drop into - that is not a good look! Small imperfections can be filled with cornice cement or base coat, but steer away from using plaster products on large areas under tiling because the adhesive often won't stick. I have used a cement based flexible tile adhesive to screed out imperfections (using a straight edge of suitable length) - but generally only where larger tiles were being used.
As long as you ensure that there is a good seal between the bench and the wall, you don't need to waterproof a splashback. BTW is it plasterboard or solid plaster wall?

To apply the tiles, start at the top and use a non-slump mastic such as abamastic or davco supermastic and apply it with only a 3mm nothched trowel. Any bigger and the adhesive will squeeze betweem the tiles when you bed them. Snap a level chalk line or draw a pencil line for to line up the top edge of the sheet. Plan the height of the line so the mosaics fit without cutting and remember you can slice rows of tiles off - you are not limited to the full sheet (sounds obvious I know). Also make a plumb line to start an edge of a sheet - again planning to avoid cutting mosaics. If you find that you have gaps at the bottom/edges that will not fit a tile you can cut the webbing behind several rows or columns and slightly shrink the groutlines or expand the groutlines to bring it to a nice conclusion.
So to apply the tiles: apply the adhesive (maybe just enough for one square for the first sheet in case you muck up) then with another clean trowel (plasterers trowel, steel float or the like) pick up a sheet of mosaics (the sheet hangs by the first row from the trowel) and press the trowel into the adhesive making sure the edges of the sheet line up with the setout lines. While you hold the sheet with the trowel, gently push the rest of the sheet into the bed. It will stay put now. Use the float to ensure all the tiles are bedded check the gaps are good. If you're feeling confident, lay out enough adhesive for several sheets and go for it.

Hope you understand my garble.

goodluck

Cheers
Michael

Quote:

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Originally Posted by FishHead

G'day All,
I have a few questions regarding a planned ceramic mosaic kitchen splashback (I have never tiled before).

The wall was tiled previously and pulling the old (large) tiles off has revealed a wavy, uneven wall. How flat does the plaster have to be when using mosaics and what is the best way to achieve this (eg. Skim coat with an extra large applicator)?

Do I then apply a primer or a sealer to the plaster/skim coat or is it waterproofing compound, or are these the same thing?

How thick do I apply the glue and what do I apply it with?

The shape of the splashback is an 'upside-down T-shape' (rectangular if not for the overhead cupboards on each side in other words). Where do I start the tiling (ie. At the top or the bottom, the middle or one side etc)?

Any help would be appreciated.

Regards,
FishHead

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:2tsup:

G'day Mic-d,

Thanks a lot for your comprehensive reply - much appreciated.

Yep, the sheets are 300 X 300, as you say. And the walls are solid plaster, not plasterboard.

I have actually already used CSR patching cement over quite large areas already, to try to get a perfectly flat surface. Because this is a plaster-type product, will I have to seal this with something first? What would be the best thing to use?

Also, am I to avoid cutting the tiles at all? I mean, are they very difficult to cut neatly?

Do I apply some kind of sealer on top of the tiles and grout after they are laid?

Thanks and regards,

FishHead

paint those areas with wallboard sealer.
If you can avoid cutting mosaics by spending a little time on setout, it is better, especially if they are small tiles eg 1-2cm. With these smaller tiles it is easy to squeeze up or stretch out a number of groutlines to include/exclude and extra line. It may not be possible to avoid with larger tiles or if corners fall in the middle of runs. You can use a grout sealer if you wish. it will keep the grout clean.

Cheers
Michael

Thanks for your help Mic-d!

Cheers,

FishHead