Installing tiles seems simple, until it’s not. One small oversight can lead to cracks, uneven tiles, or worse, a full redo. Whether you're working on a bathroom upgrade or laying large format tiles in your kitchen, here are five of the most common installation mistakes DIYers make, and how to avoid them.

1. Skipping Surface Prep (or Rushing It)

This is where most DIY jobs go wrong. Tiling over an uneven surface guarantees future problems. Large format tiles (anything over 15 inches on any side) are especially sensitive to dips, bumps, and irregularities.

Why it matters:
Large format tiles require a substrate flat to within 1/8 inch over 10 feet (TCNA Handbook, 2024). If your base isn’t properly prepared, tiles won’t sit flush, leading to lippage and weak adhesion.

What to do instead:

• Use a straightedge to check your subfloor.

• Patch and level the surface before installing.

• Always prime porous surfaces.

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2. Using the Wrong Trowel Size or Technique

The trowel you use determines how much adhesive gets under your tile. And not all tiles—especially large format are created equal.

Industry insight:
According to Custom Building Products, large format tiles require a minimum 95% mortar coverage to prevent voids under the tile that can cause cracking.

What to do instead:

• Use a 1/2" x 1/2" square notch trowel for large tiles.

• Apply thinset in straight lines, not swirls.

• Back-butter each tile for full coverage.

3. Ignoring Expansion Joints

Tiles don’t exist in a vacuum, your home moves, expands, and contracts. Ignoring this is a recipe for cracked grout or tiles.

Reality check:
The Tile Council of North America (TCNA) states that movement joints should be placed every 20 to 25 feet indoors and 8 to 12 feet outdoors or in sun-exposed areas.

What to do instead:

• Use soft joints where tile meets walls, columns, or fixtures.

• Plan for temperature and moisture changes—especially in bathrooms or patios.

➡️ Read more: Quick Tips for Flawless Restroom Tile Installation

4. Not Using the Right Mortar for Large Format Tiles

Using standard thinset for large tiles? Not a good move. These tiles are heavier and require stronger bonding agents to stay in place.

Best practice:
Use a medium-bed mortar (now called LHT mortar) for tiles larger than 15" on any side. This supports the extra weight and prevents sagging.

Bonus tip:
Use a white mortar for light-colored or translucent tiles to avoid discoloration.

5. Grouting Too Early

This one’s a rookie mistake. Rush the job, and your tiles shift or lift.

How long should you wait?
24 to 48 hours, depending on the adhesive and environmental conditions. Follow the mortar manufacturer’s guidelines.

Quick stat:
According to Schluter Systems, premature grouting is one of the top causes of hollow tiles and cracking joints.

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Final Thoughts: DIY Smart, Not Just Fast

DIY tile installation isn’t impossible—but the margin for error is small, especially with large format tiles. Slow down. Use the right tools and materials. And follow proven techniques.

If you're unsure or want to start with quality materials, explore our full tile collection. We stock a wide range of durable, easy-to-install tiles, including large format options that work for both home and commercial spaces.

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Explore More:

• Tile Size Guide: Choosing the Right Tile for Your Space

• Restroom Tile Maintenance Hacks

• Shop Our Grid Series Collection
  
  

  Frequently Asked Questions

  1. What’s the most common mistake DIYers make when installing tile?

  The most common mistake is poor surface preparation. Skipping this step can lead to uneven tiles, weak adhesion, and cracked grout lines. Always start with a flat, clean, and dry substrate.

  2. Can I install large format tiles without a leveling system?

  Technically yes, but it's not recommended. Large format tiles are more prone to lippage (height differences between tiles), and using a tile leveling system ensures a smooth, professional-grade finish. Most pros, including Schluter Systems, recommend leveling clips for any tile over 15".

  3. How do I know if my subfloor is ready for tile installation?

  Your subfloor should be structurally sound, clean, level, and dry. For large format tiles, it should have no more than 1/8" variation over 10 feet, per TCNA guidelines. Use a long level or laser tool to check.

  4. What trowel size should I use for large format tiles?

  Use a 1/2" x 1/2" square-notch trowel as a minimum. This helps ensure full mortar coverage under the tile, which is essential for durability. Check by lifting a tile and inspecting the back for at least 95% coverage.

  5. Can I use the same thinset mortar for large tiles and regular tiles?

  No, large tiles require medium-bed or LFT (Large Format Tile) mortar, which is formulated to support the weight and size of larger tiles without sagging or shrinking.