What Is Lippage in Tile? (And How to Stop It Before You Set the Next Tile)
Lippage is the technical word for the height difference between two adjacent tiles — the lip you feel under a bare foot, the shadow under the kitchen light. It is the #1 visual flaw in a DIY tile install, and the industry has been writing specs about it for decades because it is the part of tile work that gets a complaint and a callback.
How much lippage is "too much"?
ANSI A108.02 (the spec the TCNA Handbook references) allows lippage of 1/32" plus the tile's own inherent warpage for grout joints 1/16" to under 1/4", and 1/16" plus warpage for joints 1/4" and wider. Because the inherent warpage of the tile is added on top of the lippage number, a large tile can show more lip than 1/32" and still pass the standard — see TCNA's Warpage, Lippage, and Related Challenges write-up for the full breakdown. In plain terms: any lip you can clearly feel with the side of your hand is at or over spec on a residential floor.
The three causes (and which one is yours)
- The substrate is not flat. Most common cause, and almost always invisible until tile is on top. The ANSI A108.02 flatness spec for tiles 15" or larger on a side is no more than 1/8" in 10 feet AND 1/16" in 24" (versus 1/4" in 10 ft for standard tile) — most plywood subfloors and even newly poured slabs miss that without self-levelling. The Ceramic Tile Education Foundation's primer on large-format flatness walks through the test. Lay a long level across the bare substrate; if it rocks more than a credit card's thickness, you have a substrate problem, not a tile problem.
- The thinset bed is too thin (or the notch is too small). A 1/4" V-notch under a 12×24" porcelain tile leaves no room to press the tile flat. TCNA does not specify a trowel notch directly — it specifies 80–95% mortar coverage under the tile (80% in dry areas, 95% in wet or exterior installs), and a 1/2" square notch is the common way to hit that under tiles 15" or larger. Even some 12×12 floor tiles benefit from the bigger notch on a wavy substrate. Back-buttering the back of the tile helps fill voids that cause spot-lippage.
- Adjacent tiles cured at different heights. Even with a flat substrate and the right trowel, two tiles can set just-different. A tile leveling system — clips between tile edges with a wedge or spin-cap that pulls them flat — locks adjacent tiles into the same plane until the thinset sets, then snaps off at the grout line.
Stop it before you set the next tile
- Self-level the substrate first if it is not flat. Floor self-leveller is sized using the backer-board calculator for area coverage. Walls get shimmed or screeded; you cannot pour level on a vertical surface.
- Use the right notch for the tile size. The trowel size chart matches notch to tile dimension — undersize trowels are the most common DIY lippage cause after a wavy substrate. Size up, not down.
- Set a leveling clip at every joint. One clip mid-side on long edges, every 8–12". The clip will not fix a substrate dip — it will only pull tile edges into the same plane the thinset is already cured to. Get the substrate right, then the clips handle the last bit.
- Beat the tile in with a rubber mallet (gently). Two or three taps along the centre of the tile to seat it fully into the thinset before it skins over. The thinset calculator sizes the bag for whatever notch you ended up using.
What prevents lippage
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links; the price you pay is the same and it helps keep this tool free.
Spin Doctor Tile Leveling System 3/16" Bases (250 pc)
The bases sit under the tile edge and pull adjacent tiles flat as you spin the cap down. The 3/16" gap suits most standard floor and wall installs; pair with the matching caps.
Marshalltown 1/2" × 1/2" × 1/2" Square-Notched Trowel
A bigger notch lays a thicker bed of thinset so a slightly out-of-flat tile can be pressed down to its neighbours instead of sitting proud. A 1/2" square notch is the common way to hit the 80–95% mortar coverage TCNA requires under large-format tile.
Stabila Type 196-2 K Mason Level, 48"
Most lippage starts in the substrate, not the tile. A 4-foot level across the floor or wall finds the dip or bow that no leveling clip can fully fix, so you self-level (or shim) before the thinset goes down.
Why icons, not product photos? Amazon only allows their product images through the Product Advertising API, which unlocks after the first few sales. Until then these cards use our own graphics (no scraped images = no ToS risk) and swap to live photos & prices automatically once the API is on.
Related
Picking the right thinset for a large-format job? Thinset calculator for large-format tile sizes the bag at the bigger notch. Sealing a stone install where lippage looks worse? Tile sealer calculator covers the sealing step.