ACT Large Format Tile key terms

Tile with at least one edge length of 15 inches or more, or with a face area of 1 square foot or greater. Its size and weight demand specialized handling, mortar, and leveling practices.

The permitted variation of a floor or wall surface from a true plane, commonly 1/8 inch in 10 feet for large tile. Excess variation must be corrected before installation or lippage results.

The cleaning, repair, flattening, and priming of a surface so it can accept tile and mortar. Proper preparation ensures bond, flatness, and long-term performance of the finished assembly.

A pourable cementitious compound that flows out to create a flat, smooth surface over a prepared substrate. It is often used to bring floors within flatness tolerance before large tile installation.

A liquid applied to a substrate or underlayment before mortar or self-leveling compound to improve adhesion and control absorption. Using the wrong or missing primer can cause bond failure or premature drying.

The downward bending of a floor structure under load. Excessive deflection causes tile and grout cracking, so floors must meet a stiffness standard before large tile is installed.

A cement-based adhesive mixed with water or latex additive and applied in a thin layer to bond tile to a substrate. Large tile requires thin-set rated for the tile size and service conditions.

A thin-set mortar formulated to resist sag and support heavy tile, often labeled for large-format use. It provides better body and coverage than standard thin-set for big, dense tile.

The percentage of the tile back actually contacted by mortar. Large tile generally requires near-complete coverage to support loads and prevent hollow spots and cracking.

Spreading a thin layer of mortar directly on the back of a tile before placing it. This improves bond and coverage, especially important for large tile and exterior or wet applications.

A trowel with square or U-shaped teeth that comb mortar into ridges of a controlled depth. Tooth size and shape are chosen to match tile size and desired coverage.

A dry mortar that is mixed with a latex additive or contains polymer modifiers to increase bond strength and flexibility. It is often specified for demanding or exterior installations.

The downward slip of mortar or tile on a vertical surface before the material sets. Large and heavy tile mortars are formulated to resist sag on walls.

The process of determining tile orientation, starting points, and cut locations before installation. Good planning balances cuts, centers the pattern, and minimizes waste and awkward slivers.

A reference line snapped or drawn on the substrate to guide tile placement and keep courses straight and square. It anchors the layout and is checked against room geometry.

A pattern of chalk or reference lines forming squares on the floor, used to place tile consistently and check alignment. It helps maintain joint width and squareness across a large area.

A difference in height between the edges of adjacent tiles, creating a step or lip at the joint. It is controlled by flat substrate, proper mortar, and leveling systems.

A set of clips, wedges, or spacers that hold adjacent tile edges at the same height while mortar cures. These systems reduce lippage on large tile but do not replace proper substrate flatness.

A leveling method using plastic clips under tile edges and wedges pushed into the clips to pull edges flush. Clips are broken off after the mortar sets.

A natural curvature or bow in a tile caused during manufacturing. Warpage makes edges sit at different heights, so wider joints and leveling systems help hide lippage.

A gap or flexible joint in the tile assembly that allows expansion and contraction without cracking tile or grout. It is required at changes of plane, perimeters, and large field areas.

A movement joint that accommodates thermal and moisture expansion across a large tiled area. It is typically placed at intervals and at transitions between different substrates.

A movement gap left between tile and walls, cabinets, or other fixed elements. It allows the floor to move independently and is often filled with flexible sealant.

A flexible, often silicone-based material used to fill movement joints instead of rigid grout. It absorbs movement and keeps joints watertight at changes of plane.

A sheet or liquid-applied layer that prevents water from reaching the substrate in wet areas. It is installed under tile in showers, decks, and other moisture-prone locations.

A flexible collar or flange on a drain or fixture that is sealed to the waterproofing membrane to create a continuous barrier. It prevents water from bypassing the waterproof layer at penetrations.

A test that fills a waterproofed area with water for a set period to check for leaks before tile is installed. It verifies the membrane and its connections are watertight.

A power saw with a water-cooled diamond blade used to cut tile accurately. Water reduces dust and heat while the diamond blade cuts hard porcelain and stone.

A cutting blade with diamond grit bonded to its rim, used to cut hard tile and stone. Blade type and continuous or segmented rim are matched to the material being cut.

A dense, low-absorption tile made from fine clay fired at high temperature. It is strong and water-resistant but hard to cut and requires appropriate mortar and blade.

Loss of adhesion between tile, mortar, and substrate, causing hollow spots or loose tile. It results from poor coverage, dirty surfaces, wrong mortar, or excessive deflection.

An area under a tile where mortar is missing, heard as a dull sound when tapped. Large hollow spots signal inadequate coverage and risk cracking or debonding.

Safety gear such as eye protection, gloves, hearing protection, and respiratory protection worn during tile work. It protects against silica dust, cuts, and noise on the jobsite.

Fine airborne particles released when cutting or grinding concrete, tile, or stone. Prolonged exposure can cause serious lung disease, so dust controls and respiratory protection are required.

Published consensus documents, such as ANSI and TCNA guidelines, that define materials, methods, and tolerances for tile work. They provide the accepted baseline for quality and code compliance.