Marble tiles on sloped ceiling

[Sean Kelly]

That was a full tiling course in one post!

 

[Adam Heron]

Errrm what’s a standard flat bed trowel?
Important things to note.
The flatter the substrate, (hardiebacker) the easier life will be and the amount of adhesive required will not be excessive.
Your goal is to achieve a full bed of adhesive beneath the tile, but just enough to achieve it, not excessive amounts. The thinner the full bed, the more strength it will have, and the more suction you can create to hold them in place.
Before fixing make sure the substrate, and the back of the tiles are dust free.
Hardiebacker state that priming is not required, only a wipe with a damp cloth to remove dust.
Many of us will prime regardless, but not a strong mix, enough to reduce suction from the board.
Yes you want to create suction between tile and substrate, but you do not want there to be a stronger suction between adhesive and substrate.
If this happen, moisture will be drawn to quickly from the adhesive and a brittle joint will be created.
Bit like a dry joint in soldering.
Priming the hardiebacker with an acrylic primer will slow down this suction between adhesive and board.
Trowel a 10mm notch of adhesive on to the hardiebacker, make sure it is all in the same direction.
The direction is determined by the size of the tile, it should be across the shortest distance ie with a 600 x 300, you should trowel parallel to the 300 side.
The reason is that when you bed the tile in you can expel all the air from beneath, troweling parallel to the 300 side allows the air to move over the shortest distance possible.
If you ‘rainbow trowel’ the substrate with adhesive, air will become trapped beneath when you bed it in.
Then take the back edge of the trowel and spread a thin coat of adhesive on the back of the tile, bedding in the adhesive as much as possible, forcing it in to the back.
This will provide a much better key on the tile, once keyed leave a 1mm skim on the back and bed your tile to the hardie.
Work the tile forward backward, or side to side which ever is required to break the ribs of adhesive beneath. Ie ribs left to right, move up and down, and vice versa.
Then remove the tile carefully, it should not be easy, it should have a full bed, so removal will be tricky.
If it drops away easily, there is insufficient adhesive to cope with either the unevenness of the substrate or tile.
Two options, increase size of trowel on substrate to 12mm, or use a very fine notch on the back of the tile as well as the 10mm on substrate.
Increasing to 12mm would be my choice, leaving a flat skim in the tile.
Work clean at all times, keep your tiles free of excess adhesive, and regularly clean out the joints as you go.
In essence, that’s it.
You can go further with the introduction of levelling clips, but for tonight at least, that’s your lot.

Megarapid and full Raimondi RLS kit ordered. Could I have your business email please 3_fall.