Hey Kayse,
Great question
Trowel size depends on a few factors
- Size of tile
- Thickness of tile
- Coverage of thinset (transferred to tile when spread;100% being the goal)
Smaller tile require less thinset to achieve full coverage and makes things eaiser, and if the thickness of thinset doesn’t exceed the thickness of tile it help prevent too much thinset from oozing out of joints when setting (mostly pertains to smaller mosaic tiles on a sheet)
For installing membranes, the size trowel will be specified by manufacture
- Schluter Kerdi – 1/4″ x 3/16″ V-nothch or 1/8″ x 1/8″ square; or the official Kerdi trowel: https://amzn.to/2GU9YkU
- Schluter Ditra – 5/16″ x 5/16″ V-notch or 3/16″ x 3/16″ square; or the official Ditra Trowel: https://amzn.to/2qugDHB
Generally, I like using these trowels for installing these sized tiles:
- 2″ x 2″ tile – 1/4″ thick – 1/4″ x 1/4″ square notch
- Subway tile and tile under 8″ x 8″ – 1/4″ x 1/4″ square notch
- Most mosaics and borders – 1/4″ x 1/4″ square notch
- 12″ x 12″-18″ tile – 1/4″ x 3/8″ square notch
- 12″x 12″ stone/travertine – 1/2″ x 1/2″ square notch
- 12″ x 24″ porcelain on wall-1/4″ x 3/8″ or Euro trowel
- 12″ x 24″ floor tile – 1/2″ x 1/2″ square notch or euro trowel
- Plank floor tile – 1/4″ x 3/8″ square notch
I typically use a bigger trowel on a floor so that you have a better ability to eliminate lippage and compensate for any uneven floor areas
A bathroom does typically require a few trowel sizes to accomplish things
If you use too large sized trowel for the membranes…you will end up with a lot of build up making it tough to flatten out, so I would suggest sticking with the manufactures recommendation
Hope this helps
.
