Tile Lippage: Causes, Prevention, and Fixes

The Tile Installer's Secret to Zero Lippage (And Why Most DIYers Get It Wrong)

The Bottom Line: 

One sentence answer: Tile lippage is when one tile edge sits higher than the adjacent tile, creating a tripping hazard and an ugly floor, and it happens because of uneven subfloors, bad thin set coverage, incorrect trowel technique, or using tiles that are not flat.

A Quick Overview (For People Who Want the Bottom Line)

Lippage is every tile installer's nightmare. You step back to admire your work and you see it. One edge of a tile sticks up like a little ramp. Your finger catches on it. Your toe will definitely feel it. And now you are staring at a floor that looks amateurish and feels dangerous.

The good news is that lippage is almost always preventable. The bad news is that fixing it after the thin set has dried is a huge pain. You either live with it, or you pull up tiles and redo them. That is why this article exists. I am going to walk you through exactly what causes lippage, how to prevent it from ever happening, and what to do if you already have it.

Grab a cup of coffee. Let us save your floor.

What Exactly Is Tile Lippage?

Let us define the term clearly. Lippage occurs when the edge of one tile is higher than the edge of the tile next to it. The difference might be as small as a credit card thickness or as large as a quarter inch. Even a tiny lip can catch a bare foot or a vacuum cleaner. A big lip can trip someone or crack a tile.

The tile industry has standards for how much lippage is acceptable. According to the Tile Council of North America (TCNA), for tiles with a grout joint width of 1/16 inch to 1/4 inch, the allowable lippage is 1/32 of an inch for tiles that are 6 inches or smaller. For larger tiles, it gets more complicated. But here is the real world rule. If you can feel it with your finger, it is too much. If you can see a shadow under a straight edge, it is too much.

Lippage is not just cosmetic. It creates a tripping hazard, especially in bathrooms where floors are often wet. It makes cleaning harder because dirt collects at the raised edge. It can cause the high edge to chip or crack over time. And it looks terrible, which is reason enough to avoid it.

Why Does Lippage Happen? The Root Causes

Lippage is rarely caused by one thing. It is usually a combination of factors. Let me break down every possible cause so you can check your own project.

Cause 1: An Uneven Subfloor

This is the number one cause of lippage by a long shot. Your subfloor must be flat. Not level, but flat. Level means horizontal relative to gravity. Flat means no bumps or dips. You can have a sloped floor that drains toward a shower and still have no lippage, as long as it is flat. But if your subfloor has a dip in the middle or a hump near a wall, your tiles will rock and create lippage.

The industry standard for flatness with tiles up to 15 inches on any side is no more than 1/4 inch variation in 10 feet. For larger tiles, it is even stricter. You want no more than 1/8 inch in 10 feet. Most subfloors, especially in older homes, do not meet this standard.

Cause 2: Tiles That Are Not Flat

Here is something that surprises many people. Tiles are not perfectly flat. Larger format tiles, especially wood look planks, often have a slight bow or cup. Place two tiles face to face and you will see a gap. That is called warpage. When you install a bowed tile, the middle might sit higher than the edges, or the edges might curl up. That creates lippage no matter how flat your subfloor is.

Manufacturers have tolerances. But those tolerances can still produce noticeable lippage. The longer the tile, the more pronounced the bow can be. A 24 inch plank might have a bow of 1/16 inch. Pair that with another tile that bows the opposite way, and you have 1/8 inch lippage. That is unacceptable.

Cause 3: Wrong Thin Set or Mortar Consistency

Thin set mortar is not all the same. Some are designed for large tiles. Some are for walls. Some have additives for flexibility. Using the wrong thin set can cause lippage because the mortar does not hold the tile in place properly.

Even with the right thin set, if you mix it too wet or too dry, you have problems. Runny mortar lets tiles sink unevenly. Stiff mortar does not allow you to bed the tile fully. Both create lippage.

Cause 4: Incorrect Trowel Size or Technique

The trowel you use determines how much thin set stays under the tile. A trowel with notches that are too small leaves too little mortar. The tile does not have enough support and can sink in some spots. A trowel with notches that are too large leaves too much mortar, which makes the tile hard to press down evenly.

Your trowel technique matters just as much. If you do not hold the trowel at a consistent angle, the notches will be uneven. If you do not comb the mortar in straight lines, you get ridges that do not collapse evenly. And if you do not back butter large tiles, you will have voids that lead to lippage.

Cause 5: No Back Buttering on Large Tiles

Back buttering means spreading a thin layer of thin set on the back of the tile before you set it into the mortar on the floor. For tiles larger than 12x12 inches, back buttering is not optional. It is required. It fills any warpage in the tile and ensures full coverage. Skipping this step is a fast track to lippage.

Cause 6: Not Using Tile Leveling Systems

Tile leveling systems are plastic clips and wedges that hold adjacent tiles flush while the thin set dries. They are cheap and incredibly effective. Some old school tilers say you do not need them. Those tilers also have lippage. For any tile larger than 12 inches, use a leveling system. It is the best insurance policy you can buy.

Cause 7: Rushing the Installation

Thin set stays workable for a limited time. That time is called pot life. If you spread too much mortar at once, the surface can skin over before you set the tile. When that happens, the tile does not bed properly. You end up tapping it down unevenly, creating lippage.

Also, if you step on a freshly set tile or rest a knee on an adjacent tile, you can push it down too far. Then the neighboring tile looks high. That is lippage from impatience.

Cause 8: Subfloor Movement or Deflection

If your subfloor flexes under weight, your tiles will move. That movement can cause lippage over time, even if the installation started flat. The fix is to ensure your subfloor is stiff enough. For tile, you need a deflection rating of L/360 or better. That means the floor bends less than 1/360th of its span. For a 10 foot span, that is about 1/3 inch of maximum deflection. If your floor bounces, you need to reinforce it before tiling.

How to Prevent Tile Lippage Before You Start

Prevention is easier than fixing. Much easier. Here is your pre installation checklist.

Step 1: Check Your Subfloor Flatness

Get a long straight edge. An 8 foot level works perfectly. Lay it on the floor in multiple directions and locations. Slide a piece of paper or a thin coin under the straight edge. If you can slide a quarter under it, that is about 1/16 inch. If you can slide a stack of two quarters, that is 1/8 inch. Mark any high spots and low spots.

High spots need to be ground down with a floor grinder or a cup wheel on an angle grinder. Low spots need to be filled with floor patch or self leveling compound. Do not skip this step. Fixing the subfloor is cheap and fast. Fixing lippage after tiling is neither.

Step 2: Inspect Your Tiles for Warpage

Open several boxes from different parts of your pallet. Take two tiles and put them face to face. Squeeze one edge closed and look at the opposite edge. If you see a gap, that is warpage. Do the same test with the tiles back to back. If the gap is more than 1/16 inch, you have a problem.

Some warpage can be hidden with a leveling system and good thin set. But extreme warpage means you should return the tiles and get a flatter batch. The Tile Shoppe will help you exchange them. Better to know before you start.

Step 3: Use the Right Thin Set for Your Tile Size

For tiles up to 12 inches, a standard modified thin set is fine. For tiles larger than 12 inches, you need a medium bed mortar or a large format tile mortar. These have larger aggregate and more body. They hold the tile up instead of letting it sink. They also allow you to build thickness without shrinkage.

Read the bag. It will say what size tiles it is rated for. Follow that recommendation.

Step 4: Choose the Correct Trowel Size

Here is a general guide for trowel notch sizes based on tile size.

For planks, use a slant notch trowel designed for planks. It leaves ridges that collapse more evenly.

Step 5: Buy a Tile Leveling System

Do not argue with me on this. A tile leveling system costs maybe 50 to 100 dollars for a whole house. It includes reusable clips and wedges. You place a clip under the edge of two adjacent tiles, then drive a wedge into the clip to pull both tiles flush. The thin set dries, then you snap the top of the clip off and grout over it.

The best systems include a tension gun that applies consistent pressure. Do not buy the cheapest generic ones. Get a reputable system from The Tile Shoppe or a trusted brand. Your knees and your eyes will thank you.

Step 6: Plan Your Layout to Avoid Problem Areas

Sometimes lippage happens because you force a tile into a tight spot. Leave room for adjustment. Start from the center of the room, not the walls. Dry lay a few rows to see how the tiles interact. If you notice that two warped tiles keep fighting each other, separate them. Put a flat tile between two bowed tiles. Mix up the bow directions so they cancel each other.

Step 7: Mix Your Thin Set Correctly

Follow the bag instructions exactly. Use the correct amount of water. Mix for the full recommended time, usually 3 to 5 minutes. Let it slake (rest) for the recommended time, usually 10 minutes. Then mix again briefly. Do not add more water after it starts to set. Do not use thin set that has been sitting too long. Fresh mortar behaves predictably. Old mortar does not.

How to Install Without Lippage (Step by Step)

You have prepped everything. Now let us lay tile the right way.

Step 1: Spread Only What You Can Cover in 15 Minutes

Do not spread a huge area of thin set. Spread enough for maybe three or four tiles at a time. The open time of thin set is about 20 to 30 minutes in normal conditions. Hot or dry air shortens that time. If the mortar skins over, scrape it off and spread fresh.

Step 2: Comb the Mortar in One Direction

Use straight, parallel lines. Do not swirl the trowel. Do not make circles. Straight lines allow air to escape when you press the tile down. Consistent notch height comes from holding the trowel at a consistent angle, usually 45 to 60 degrees.

Step 3: Back Butter Every Tile Larger Than 12 Inches

Spread a thin, flat layer of thin set on the back of the tile using the flat side of your trowel. This fills the waffles and any warpage. Then comb a second layer on the floor. The back butter layer does not need to be notched. Just a skim coat.

Step 4: Set the Tile and Press Firmly

Place the tile into the mortar. Wiggle it slightly to collapse the ridges. Do not slide it far, or you will push mortar into the joints. Use a rubber mallet and a beating block to tap the tile down. A beating block is a flat piece of plywood or a commercial pad. It distributes the force evenly.

Step 5: Insert Leveling Clips Immediately

Place the base of a leveling clip under the edge of the tile before you set the adjacent tile. Position it so the clip spans the joint. When you set the next tile, it rests on top of the clip. Then insert the wedge and tighten. Do this on every joint, every side of every tile. It takes time but it is worth it.

Step 6: Check Continuously With a Straight Edge

Do not trust the leveling system alone. Run a straight edge across your tiles every few rows. Look for light underneath. If you see a gap, adjust that tile before the mortar sets. You have maybe 20 to 30 minutes of adjustment time.

Step 7: Let the Thin Set Cure Fully

Do not walk on the floor for at least 24 hours. Do not remove the leveling wedges for at least 12 hours. Do not grout for 24 to 48 hours depending on the mortar. Rushing the cure time can cause movement and lippage.

How to Fix Lippage After the Thin Set Has Dried

Okay, you did not read this article first. Or something went wrong. You have lippage. Now what?

Option 1: Live With It (If It Is Very Minor)

If the lippage is less than 1/32 inch and you can barely feel it, you might choose to ignore it. Grout can hide a little bit. A thick grout joint of 1/4 inch can absorb some variation. But be honest with yourself. If it bothers you now, it will bother you forever.

Option 2: Remove and Replace the High Tile

This is the proper fix. You need to take out the offending tile and reinstall it.

Step 1: Protect surrounding tiles with masking tape and cardboard.
Step 2: Use a hammer and a cold chisel to break the high tile. Start in the center and work outward. Wear safety glasses. The tile will send sharp shards flying.
Step 3: Remove all broken pieces. Chisel off the old thin set from the subfloor. Be careful not to damage adjacent tiles.
Step 4: Vacuum thoroughly.
Step 5: Clean the edges of the surrounding tiles. Any old thin set on those edges will prevent the new tile from sitting flush.
Step 6: Dry fit the replacement tile. It should sit at the same height as the neighbors. If it is too high, you need to remove more thin set. If it is too low, you need to add more thin set.
Step 7: Spread fresh thin set. Back butter the tile. Set it in place using leveling clips.
Step 8: Wait 24 hours. Grout the new joint.

This works. But it is a pain. And you risk damaging adjacent tiles. If you have multiple lippage spots, you might be better off redoing a larger section.

Option 3: Grind Down the High Edge (Not Recommended)

You can rent a diamond grinding cup and carefully grind down the high edge of a tile. This makes the lippage less severe. But you will remove the factory edge and the glaze. The ground area will look dull and rough. You can try to polish it, but it will never match. This is a last resort for a tile that cannot be replaced, like an obsolete pattern.

Option 4: Call a Professional

If the lippage is widespread, if the floor is large, or if you are just exhausted, call a tile contractor. A pro can assess whether spot repairs are possible or if the whole floor needs to come up. It will cost money. But it might cost less than your time and frustration.

Common Myths About Lippage

Let me bust a few myths before you hear them from someone else.

Myth 1: "Self leveling underlayment fixes everything." No. Self leveler makes the floor level, not necessarily flat. It can still leave bumps if you do not spread it correctly. And it adds weight. Use it correctly or not at all.

Myth 2: "Bigger grout lines hide lippage." Yes, but only a little. A 3/8 inch grout line can hide a 1/32 inch lip. It cannot hide a 1/8 inch lip. And wider grout lines collect dirt and look dated. Do not rely on grout to fix bad installation.

Myth 3: "You only need to back butter large tiles if the subfloor is uneven." Wrong. You back butter to fill tile warpage, not subfloor issues. Even on a perfect subfloor, a bowed tile needs full coverage.

Myth 4: "Tile leveling systems crack tiles if you tighten too much." Cheap systems might. Good systems with a tension gun apply consistent pressure. If a tile cracks, it was probably already damaged or the subfloor moved. That said, do not go crazy. Snug is enough. Hulk tight breaks tiles.

Myth 5: "Lippage is always the installer's fault." Not always. The subfloor might be bad. The tiles might be warped beyond spec. The thin set might be old or wrong. Sometimes the installer inherits a mess. But a good installer checks for these problems before starting and either fixes them or tells the customer.

A Quick Reference Table: Causes and Solutions

Frequently Asked Questions

How much lippage is acceptable?

Industry standards say 1/32 inch for tiles with small grout joints. But if you can feel it with your fingernail, it is too much. Aim for zero. That is achievable with good prep and a leveling system.

Can I sand down a high tile edge?

You can, but you will ruin the finish. The tile will look dull and feel rough. Only do this in a closet or an area that will be covered by a rug.

Will the leveling system work on any tile?

Most work on tiles from 2 inches to 24 inches. Some systems handle planks up to 48 inches. Check the product specs. For very small mosaic tiles, you do not need leveling clips. For very large tiles, you need a heavy duty system.

How long after tiling can I remove the leveling wedges?

Most manufacturers say 12 to 24 hours. Remove them too soon and the thin set is not hard enough to hold the tile down. Remove them too late and they can be harder to snap off. Read your leveling system instructions.

Do I need to level the floor or just flatten it?

Flatten. Level is nice but not required. A bathroom floor can slope toward a drain. That is fine. A kitchen floor can slope an inch over 20 feet and still have no lippage if it is flat. Focus on flatness first.

What if my subfloor is concrete and has a hump?

Grind it down. Rent a concrete grinder from a tool rental place. Wear a respirator. Concrete dust is nasty. Vacuum with a HEPA filter. Then prime and use self leveler for any low areas.

Can I fix lippage by tapping the high tile down after the thin set has partially set?

No. Once the thin set has begun to cure, tapping just creates cracks or breaks the bond. You have about 20 minutes of adjustment time. After that, leave it alone or pull it up.

A Final Word From The Tile Shoppe

Lippage is one of those problems that separates a good floor from a great floor. Anyone can slap down tiles. But a floor that feels smooth under bare feet, that does not catch a vacuum cleaner, that looks like a single continuous surface, that takes attention to detail.

The good news is that lippage is almost entirely preventable. A little extra time on subfloor prep. A few dollars for a leveling system. The discipline to back butter every large tile. These are small investments that pay off in a floor you will be proud of for years.

At The Tile Shoppe, we stock everything you need to avoid lippage. Flat, high quality tiles. The right thin set for your project. Leveling systems that actually work. And people who can answer your questions before you start. Come see us. Bring your measurements. We will help you get it right the first time.

Because a floor with no lippage is not just beautiful. It is safe. It is durable. It is professional. And you can absolutely achieve it.

Now go build something you will love walking on.