Trowel Talk

Bruno Mendolini

You know, I always say, when you install tile, the first thing—first thing—you gotta think about is coverage. Without the right coverage, the whole job can, uh, how do you say, crumble, like biscotti left in milk too long.

Maria

That’s such a vivid picture, Bruno! But you're absolutely right. When the thinset doesn't cover enough of the back of the tile, you're inviting trouble. Cracking, popping, even entire tiles coming loose...

Bruno Mendolini

Exactly! The Tile Council of North America, they—they recommend 85% coverage for dry areas, and 95% for wet areas. This isn't just a suggestion, eh? It's critical. But let me tell you, I've seen the consequences when someone doesn’t follow it.

Maria

Ooh, the horror stories. Okay, spill—what's the worst case you've seen?

Bruno Mendolini

Alright, so picture this: Rome, one of those old but elegant buildings, right? A contractor was rushing—probably thinking no one would notice—and used a trowel too small for the oversized tiles. I mean, I I knew as soon as I saw it, the coverage wasn't even 70%.

Maria

Oof, that’s bad. So what happened?

Bruno Mendolini

The whole bathroom floor failed, tiles coming up like slices of pizza! Water had seeped underneath—this was a wet area—and the adhesive just couldn’t hold anymore. The client had to redo everything. It cost thousands more than if they'd just done it right the first time.

Maria

Oh my goodness, I can’t even imagine. And see, that’s why proper coverage isn't just about, you know, following the rules. It’s about creating a solid, lasting foundation. Nobody wants to redo their tile every few years.

Bruno Mendolini

No, they don’t. And here's the thing—if you can’t get the coverage, it’s often about using the wrong trowel. But we’ll get into that in a minute. For now, just remember—skimping on that coverage? It’s never worth it.

Bruno Mendolini

Now, since we’ve talked about how critical coverage is, let’s get into trowels. This choice—it can make or break your whole tile installation. You get the wrong size or shape, and suddenly your adhesive is uneven, your tiles don’t bond properly. I mean, I I’ve seen it, over and over.

Maria

Right, and it’s not just about grabbing whatever trowel’s lying around. It’s about matching the trowel to, well, everything, really—the size of the tile, the surface conditions, even the adhesive you’re using.

Bruno Mendolini

Exactly. Like, if you’re working with smaller tiles, something like a 1/4 by 1/4 inch square-notched trowel is perfect. But for larger format tiles—oh, say 12 by 24—you’re gonna need at least a 1/2-inch square-notched. Otherwise, you just—you don’t get the right coverage.

Maria

And! With large tiles, you’ve gotta factor in, like, the flatness of the substrate, right? If it’s not level, no amount of trowel size is gonna save you.

Bruno Mendolini

That’s true. The substrate surface is key. For uneven bases, sometimes you need a thicker adhesive layer, which means a bigger trowel. A 1/2-inch square-notched tends to work wonders here. And, uh, speaking of wonders, you remember that project I told you about? The one with the oversized tiles?

Maria

Oh, the residential one with the glossy porcelain? Yeah, I was dying to hear how that turned out!

Bruno Mendolini

Alright, so here’s the story. The homeowner picked these beautiful, but massive, 24 by 48 inch tiles. Gorgeous finish, but they were slightly warped—you know, a bit of cupping. I knew we’d need a 1/2-inch square-notched trowel to get the 95% coverage for that area. And, Maria, let me tell you—it worked like magic.

Maria

See, I love that! It’s such a good example of why, well, "close enough" just doesn’t work. If you’d gone smaller, there might’ve been air pockets or, worse, barely any adhesive contact.

Bruno Mendolini

Exactly! The risk of air pockets is huge—it weakens the bond and can lead to tiles cracking down the line. And get this—it wasn’t just the size of the trowel. We used a U-notched one too, to help spread the adhesive more evenly across that slightly curved surface.

Maria

Oh, that’s such a smart choice! The U-notch really does give a smoother spread, more even than a square-notch sometimes, especially for warped tiles.

Bruno Mendolini

Mmhmm. But you see, it’s not always about rules. Sometimes you gotta adapt to the tile type or the conditions. But, uh, following manufacturer guidelines... always a good place to start, eh?

Maria

Absolutely. Oh, and I love that you brought up those guidelines—it’s such an overlooked resource! I mean, they know their product best, right? So why not take advantage?

Bruno Mendolini

Yeah, it’s surprising how many people ignore that. Anyway, the right trowel—what it does is balance the adhesive amount, the coverage, and the bonding strength. If you get that part wrong, you’re setting yourself up for failure. But get it right? A beautifully installed tile that lasts for decades.

Bruno Mendolini

Now that we’ve covered why the right trowel choice is critical for a durable tile bond, let’s take it a step further. This is where we really dig into the nitty-gritty—the expert tips for pairing trowel size with tile dimensions to make sure your installation is practically flawless.

Maria

Yes! And it’s not just about choosing the right size in theory. You’ve gotta think about the tile's shape, maybe even warpage or cupping. Oh, Bruno, you know, I gotta share this story...

Bruno Mendolini

Oh, is this the backsplash one?

Maria

Yes, exactly! So, a few months ago, I was helping this couple choose a tile for their kitchen backsplash. They had fallen in love with these little hexagonal mosaics, but they were all different thicknesses. Beautiful, but, you know, a bit tricky too.

Bruno Mendolini

Ha! Mosaic tiles—always a challenge. What’d you do?

Maria

Well, first, I had to convince them not to use a huge trowel. They were eyeing a 1/4 by 3/8 inch square notch, thinking bigger meant better coverage, but for mosaics, it’s too much. So, we went with a 3/16 inch V-notch instead. Perfect for those tiny tiles!

Bruno Mendolini

Smart choice. With those notches, the adhesive flows just enough without oozing between the tiles. But how did you handle the thickness differences?

Maria

That’s where the magic of a float came in. After we pressed the tiles in, a gentle press with the float evened everything out. Oh, Bruno, it looked seamless—I was so proud!

Bruno Mendolini

Ha! I can picture it now. Well done, Maria. You know, this is what I always tell people—visual inspection can save your project. Embed the tile, lift it up, and check the coverage. I I mean, you need 85% coverage in dry areas, but if it’s wet or outdoors? 95%, no exceptions.

Maria

Exactly! And that’s actually why I love tying it back to simple tools, like just lifting the tile to check. Honestly, it’s such a small step, but it saves so much trouble later.

Bruno Mendolini

Right, and it also shows why trowel size isn’t one-size-fits-all. For larger formats—like, say, 16 by 16 or bigger—you're looking at a 1/2 by 1/2 inch square-notched. And if the tile has warpage, you may even need to angle the trowel more to increase adhesive thickness.

Maria

Or use a U-notch! I mean, you already mentioned it earlier, but it’s worth repeating. U-notched trowels are great for large or slightly curved tiles. They give such an even, smooth spread.

Bruno Mendolini

So true, Maria. And that’s why adapting to the situation and testing as you go makes all the difference. When you see that full coverage, it’s like—chef’s kiss—a perfect installation.

Maria

Couldn’t agree more. And to anyone listening, remember—don’t rush this. Take the time to match your trowel to the tile and to inspect. A little effort upfront saves big headaches later.

Bruno Mendolini

Exactly. And with that, I think we’ve given our listeners plenty to think about. Maria, it was a pleasure chatting and sharing tips as always.

Maria

Always, Bruno! And to our listeners—thank you for joining us. Happy tiling!

Bruno Mendolini

Ciao, everyone!