Red Seal Tilesetter key terms

The surface or material that tile is bonded to, such as concrete, plywood, cement backer board, or existing tile. Its condition, flatness, and porosity determine which installation method and adhesive will work.

The amount a floor structure bends or flexes under load. Excessive deflection cracks tile and grout, so installers check joist size, span, and subfloor thickness against tile industry limits before tiling.

The permitted variation from a perfectly level or planar surface, usually stated as a maximum deviation over a set distance. Tiles require a flatter substrate than most other finishes, so this is measured before layout.

A pourable cementitious or gypsum compound that flows out to create a flat, smooth surface over an uneven substrate. It is mixed to a precise water ratio and primed substrate, then left to cure before tiling.

A liquid applied to a substrate before underlayment or adhesive to control absorption, improve bonding, and keep moisture from being drawn out of the fresh material too quickly.

The period a material such as mortar, grout, underlayment, or sealant needs to reach adequate strength. Respecting cure time before foot traffic, grouting, or sealing prevents failures that are hard to repair later.

The usable working time after a two-part or hydraulic product is mixed, before it stiffens too much to apply. Installers mix only what can be placed within pot life, because re-tempering with water ruins the mix.

A cement-based adhesive mixed with water or liquid additive and applied in a thin layer with a notched trowel. It cures chemically and is the standard bonding method for most ceramic and porcelain tile.

A mortar formulated to be applied thicker than thin-set, allowing larger or heavier tile and some substrate variation to be accommodated without the shrinkage problems of thick thin-set beds.

A ready-to-use adhesive that cures by drying rather than chemical reaction. It is convenient for wall tile in dry areas but is unsuitable for wet areas, floors, or large stone because it can re-emulsify.

The window after spreading adhesive during which tile must be embedded while the mortar still transfers to the tile back. If a skin forms, the bond fails, so installers test by touching the ridges.

A trowel with square, U-shaped, or V-shaped teeth that comb adhesive into uniform ridges. Tooth size and shape control how much mortar is deposited and how much air escapes when tile is pressed in.

Spreading a thin layer of mortar directly on the back of a tile before setting it. It improves bond coverage, fills minor depressions, and is required for large-format tile and for exterior or wet-area installations.

The percentage of the tile back that is in contact with mortar. Industry standards set minimum coverage for different exposures, and low coverage is a leading cause of loose or hollow-sounding tile.

A difference in height between adjacent tiles at their edges. Slight lippage is normal, but excessive lippage is a tripping hazard, traps dirt, and is limited by standards based on tile size and joint width.

The natural curvature or bow in a tile caused during firing or forming. It can cause lippage even on a flat substrate, so installers offset tiles or widen joints to compensate.

Tile with at least one edge of roughly 15 inches or more, or with a high face area. It needs flatter substrates, deeper mortar coverage, back-buttering, and often suction cups or mechanical handling aids.

Tile whose edges have been mechanically ground after firing so dimensions are precise and square. Rectified tile allows very narrow grout joints, but it also makes lippage and layout errors more visible.

The amount of water a tile body takes up, expressed as a percentage. It classifies tile as non-vitreous, semi-vitreous, vitreous, or impervious and determines where it can be used and what adhesive suits it.

A dense, low-absorption ceramic tile made from refined clays and fired at high temperature. Its strength and frost resistance suit interior and exterior use, but it is often dark-backed and needs appropriate mortar.

A tile's ability to withstand freeze-thaw cycles without cracking or spalling. It depends mainly on low water absorption, and it governs whether a tile can be used outdoors in cold climates.

A thin sheet or mat installed between substrate and tile that separates the tile layer from movement in the structure below. It helps prevent cracks and debonding over wood, concrete, or heated floors.

A sheet or liquid-applied layer that stops water from reaching the substrate in showers, wet rooms, and balconies. It must be continuous, lapped correctly, and tied into drains and corners with reinforcing material.

A strip of waterproof material that directs water away from a junction, such as where a wall meets a floor or where tile meets a tub. It is layered so water always drains over, not behind, the next material.

A small opening left in mortar or sealant at the bottom of a wall, ledge, or pan to let trapped moisture drain out. Blocking weep holes traps water and leads to efflorescence, mold, or bond failure.

A material or coating that deliberately prevents adhesion between two layers, such as where tile meets a wall or a fixed object. It allows the finish to move independently and avoids cracking.

A deliberate gap through the tile and setting bed that lets the installation expand and contract. Joints are placed at changes of plane, large field areas, and perimeters, and are filled with flexible sealant.

The gap between tiles that is filled with grout. Width is chosen for appearance, tile size, and warpage, and it must be consistent because uneven joints make an otherwise good installation look poor.

A cementitious or epoxy-based material used to fill joints between tiles. It locks tiles together, keeps dirt and water out of the joints, and comes in sanded, unsanded, and epoxy formulations.

A white, powdery salt deposit that appears on grout or tile surfaces when moisture migrates through the material and evaporates. It is cleaned off and prevented by reducing water movement and using correct mixing ratios.

A liquid applied to grout, stone, or porous tile to reduce water and stain penetration while still allowing vapor to escape. Sealers need reapplication and do not replace proper waterproofing.

A flexible, usually elastomeric material used to fill movement joints and junctions instead of rigid grout. It stretches and compresses with the structure and must be compatible with the adjacent materials.

A small plastic, rubber, or wedge device placed between tiles to hold a consistent joint width while the adhesive sets. Spacers are removed before grouting, or left in place if designed for that purpose.

The plan for where tiles, joints, and cuts will fall on the surface. Good layout centres the field, balances cut sizes at edges, aligns with room features, and minimizes awkward slivers and waste.

A reference line snapped or drawn on the substrate to guide tile placement. Accurate control lines keep rows straight and square, and are checked against the room's actual geometry before setting begins.

A marked strip, often a straight board, used to transfer and compare course heights across a wall or floor. It helps plan whole-tile courses and keep grout lines aligned around corners and openings.

A dull, hollow noise made when tapping a tile that is not fully bonded to the substrate. Installers tap-check after curing to find loose tile before grouting or final inspection.