How to Level a Tile Floor (Subfloor Prep and Tile Leveling Guide)

A level tile floor starts before the first tile is set. Tiles installed over an uneven subfloor will rock, crack, and look unprofessional no matter how carefully they're laid. This guide covers how to level a tile floor at both stages: leveling the subfloor before tiling, and keeping tiles level during installation.

Why Leveling Matters

• Tiles over an uneven subfloor develop hollow spots and crack under foot traffic
• Uneven tiles create lippage — where tile edges are at different heights — which is a trip hazard and looks poor
• Tile adhesive can't compensate for significant subfloor unevenness — the subfloor must be flat first

Part 1: Leveling the Subfloor Before Tiling

What You'll Need

• Sika Self-Leveling Underlayment Primer — for preparing concrete subfloors
• Self-leveling compound
• Long level or straightedge (6 feet or longer)

Step 1: Identify high and low spots.

Use a long level or straightedge to check the subfloor in multiple directions. Mark high spots and low spots. Industry standard for tile is no more than 3mm variation over 3 meters.

Step 2: Grind down high spots.

Use an angle grinder with a grinding disc to grind down any high spots. Vacuum all dust before proceeding.

Step 3: Fill low spots.

Apply Sika Self-Leveling Underlayment Primer to prepare the concrete surface, then pour self-leveling compound into low areas. Allow to cure fully — typically 24 hours — before tiling.

Step 4: Re-check with a level.

After curing, re-check the floor. Repeat as needed until within tolerance.

Part 2: Keeping Tiles Level During Installation

What You'll Need

• Tile Leveling System (600 Clips + 200 Wedges)
• Rubber Mallet
• Level or straightedge

A tile leveling system is the most effective tool for keeping tiles level with each other during installation. Insert clips under tile edges, push wedges through to pull adjacent tiles to the same height, and tap with a rubber mallet to seat fully. Check with a level across multiple tiles frequently. After adhesive cures (2–4 hours), snap off clips and remove wedges for reuse.

Frequently Asked Questions

How flat does a subfloor need to be for tile?
No more than 3mm variation over 3 meters (1/8 inch over 10 feet). For large-format tiles, the tolerance is tighter.

Can I use tile adhesive to level an uneven floor?
No — tile adhesive is not a leveling compound. Use self-leveling compound for significant subfloor variations.

What is lippage in tile?
Lippage is when adjacent tile edges are at different heights. A tile leveling system virtually eliminates lippage.

Do I need self-leveling compound for every tile job?
Only if the subfloor has significant dips. For subfloors already within tolerance, just use a tile leveling system during installation.