Oh, I get why you're asking this-who wants to buy two trowels if one works, right? I've definitely tried to cut corners here before, and let me tell you: sometimes it works, sometimes it's a disaster. Let's break it down so you don't end up like me, staring at a wall of loose tiles at 9 PM on a Saturday.
First, let's talk about when it might work. If your floor and wall tiles are similar-same thickness, same size-then yeah, you can probably get away with it. For example: if you're doing a bathroom with 12x12 ceramic tiles on the floor (3/8-inch thick) and the same tiles on the shower walls? A 1/4x3/8-inch square notch trowel will work for both. I did this last year for my sister's bathroom, and it was fine-no issues, no extra trips to the store. That's the ideal scenario: matching tiles, so matching tool.
But here's where you gotta be careful-when the tiles are different. Let's say you're doing a kitchen: 12x24 porcelain floor tiles (1/2-inch thick) and 3x6 subway tiles (1/4-inch thick) on the backsplash. If you use the floor trowel (1/2-inch square notch) on the subway tiles? You'll have mortar oozing out every grout line, and you'll spend hours scraping it off. I did this once-thought "how bad can it be?" Turns out, really bad. I had mortar on my hands, my shirt, even my shoes. Never again.
Or the other way around: using a small trowel (1/4-inch V) for floor tiles. Those big floor tiles need more mortar to stay level and stick-so a small trowel won't hold enough. I laid a hallway floor with 12x12 tiles using a V-notch once, and by the time I finished the first row, half the tiles were wobbling. Had to pull 'em up, re-spread mortar with the right trowel-total waste of time.
Here's my rule of thumb: If the tiles are different in size or thickness, get two trowels. They're not that expensive-usually 10−15 each-and they'll save you so much frustration. And if you're not sure? Do a test patch on the wall and a test patch on the floor. If one looks messy or the tiles don't stick, you need a different trowel. It's better to spend a little extra now than to redo an entire project later. Trust me, I've been there.
Notched trowel from hanke tools
