The other main consideration is where the tiles will be set on the floor or on the walls and ceilings.
Notched trowel for wall tile.
V notch trowels have a continuous zig zag or sawtooth pattern with points.
When you use a 1 4 x 3 8 square notched trowel you will leave 1 4 wide by 3 8 high ridges of thinset on the substrate with spaces between each ridge.
Tile trowels come in many shapes and sizes generally starting out from a 3 16 v notch up to the 1 2 square notch.
U notched trowels normally only have one number.
Mosaic tiles and wall tiles up to about 4 by 4 inches call for a v notch trowel with 3 16 by 1 4 inch notches while larger tiles require a trowel with a square or u shaped notch to obtain proper adhesive coverage.
As 1 2 trowel means that both measurements are the same.
A tile trowel with only one measurement i e.
Tile trowels come in many shapes and sizes generally starting out from a 3 16 v notch up to the 1 2 square notch.
It just creates a better bond to the tile.
With your 12 24 tiles you should use a 1 2 notched trowel on the wall and back butter each tile but just with a skim coat.
Twelve inch square tiles for instance are best applied using a trowel with 1 2 inch by 1 2 inch notches.
They are typically used for small tiles such as mosaics or any tiles under 2 inches square.
The larger the tile the larger the trowel.
V notch tile trowels.