Tile & Stone

Tile Leveling Systems and Spacers

How clip-and-wedge leveling systems control lippage, what they can't fix, and the ANSI offset and grout-joint rules for large-format tile.

Updated · 3 min read

A leveling system holds tile edges flush while the mortar cures, which cuts down lippage. It won't make up for a wavy substrate or thin mortar coverage. Most lippage comes from an uneven substrate or thinset applied wrong.[1]

What lippage is allowed

ANSI A108.02 defines lippage as the height difference between the edges of neighboring tiles, and sets these allowances[1]:

Tile Grout joint Allowable lippage
Glazed wall tile, mosaics, pavers 1/16" to less than 1/4" 1/32"
Quarry tile, pavers 1/4" or wider 1/16"
Gauged porcelain tile and panels All 1/32"

These don't apply to floors sloped to drains. Square-edge tile shows lippage more than tile with a chamfered edge. Warpage, joint width and lighting also play a part.[2]

Start with the substrate

Clips can't flatten a floor.

Large-format rules

ANSI adds two rules for running bond with tile over 18".[1]

  • Offset: where the offset side is over 18", offset no more than 33% unless the tile maker says otherwise.
  • Joint width: an average minimum of 1/8" for rectified tile and 3/16" for calibrated tile, increased by the edge warpage of the tile.

More generally, a grout joint should be about three times the variation in the tile's facial dimensions, and never less than 1/16".[3] The same rule has been proposed for the ANSI standard.[1]

How the LASH system works

QEP LASH is a clip-and-wedge system.[4]

  • Clips fit tile 1/4" to 7/16" thick and make a 1/16" or 1/8" joint. They can be combined with regular spacers for joints up to 1/4".[4]
  • The slotted base lets mortar spread evenly so voids don't form.[4]
  • Use at least a 1/4" x 3/8" x 1/4" square notch, and back-butter.[4]
  • Clips snap off below the tile surface with a kick or a tap of a floor mallet, and the wedges can be reused.[5]

Step by step

This is the general sequence for any clip-and-wedge system.

  1. Check the substrate for flatness and correct it.
  2. Spread mortar with the specified notch and back-butter the tile.
  3. Set the tile and slide clips under the edges. For LASH XL, place clips about 2" from each end of the tile.[6]
  4. Clean excess mortar from the edges.
  5. Set the next tile, insert the wedges and tighten. The LASH pliers reach the right pressure in one or two clicks.[4]
  6. After the mortar sets, break off the clips in the direction of the grout line. For LASH XL, do this within 24 hours.[6]
  7. Grout. See Grouting tile.

Common mistakes

When lippage shows up with clips in place, it's usually one of these.

  • Using clips to fix a bad substrate.
  • Too small a notch. Coverage drops and tiles rock. See Trowel notch for tile.
  • Over-tightening wedges. It can pull tiles down unevenly.
  • Offsetting long tile at 50%. Stay at 33% or less unless the tile maker says otherwise.

Tools we carry

These are the LASH clips, wedges and trowels we stock.

References

  1. Laticrete TDS 164: Lippage, causes and prevention
  2. TCNA: Lippage FAQ
  3. Custom Building Products TB85: Grout joint width
  4. QEP LASH product data sheet
  5. QEP: LASH tile leveling system (product page)
  6. QEP LASH XL product data sheet

Linked PDF documents are archived copies saved by PreFloor Tools so they stay available if the publisher moves or removes them. Check the publisher's website for the latest revision.

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