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Glossary of Industry Terms

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Click on a Term Below for more Detail

A cement based material used to bond tiles or natural stone to a substrate.

Not all adhesives exhibit the exact same properties. Most ranges are fast setting (used mainly for floors), and slow or standard setting (usually on walls). There are also premixed adhesives available, as well as the dry powdered form.

Numerous specialised adhesives exist for less common tiling applications. It's important that, where necessary, flexible adhesive is used. A fuller discussion on tile adhesive is available here.

Also known as the PEI rating test, it establishes a rating between 0 and 5 for the quality of the surface of a glazed tile, with respect to resistance to abrasion. The higher the rating, the better quality the surface, and the more applications for which the tile can be used. We give a fuller description of the floor tile testing process here, and what the results mean.

A screed which uses calcium sulphate as its binding agent, mixed with aggregate and water. Also know as Gypsum screed. We take a closer look at anhydrite screed and link to a helpful video here, to better describe the details.

A term generally used in the trade to describe a tile with a slip resistance rating, usually assigned by the manufacturer, of 11 or more. In reality, a tile is not deemed either anti-slip or not, rather any tile can have a rating and this rating is indicative of the tile's suitability for any particular purpose. We explore all aspects of slip resistant tiles here.

This is a process whereby the clay body is fired unglazed, and then a second time with glaze. It is often repeated up to three times, in particular when building up decorative patterns.

1. An umbrella term for all tiles produced through the application of heat to clay.
2. A term used in the trade to distinguish between tiles that are porcelain and non-porcelain. Ceramic tiles can be either glazed or unglazed.

These are tiles that have a pattern which is not as a result of a glaze, but due to different colours of clay. As the tile wears over time, the pattern will not deteriorate. We illustrate many encaustic tiles with beautiful images in our style blog.

Gaps or breaks in components of a building construction, designed to allow for the movement of the components caused by thermal expansion, or dynamic forces such as wind, vibration or seismic activity. In the industry, "expansion joint" also refers to the profiles that are inserted into these gaps. We cover the area fully, with photographs of expansion joints here.

This is a tile with a PEI rating of 2 or more. A tile with a PEI rating of 1 should not be used on the floor. A tile is not deemed suitable or otherwise for use on a floor solely based on its appearance.

A ceramic or porcelain tile which is coated in a vitreous enamel glaze prior to being fired in a kiln. The glaze fuses to the tile as a result of the firing. We discuss glazed tiles in more detail here.

A cement based filler used between tiles. It comes in a coarse variety as well as a fine one. The coarse grout contains silica sand, and can be used on wider grout joints. The fine grout is less gritty and therefore is used on tight joints. There are a wide variety of grouts available, and they deliver the final touch to creating a perfect tiled finish. We discuss grouts in more detail here

A flat, smooth rubber pad used to spread grout into the joints between the tiles. The grout float is designed to prevent scratching or chipping to the face of the tile.

These are single fired, glazed tiles, produced with harder glazes and generally suitable for use on floors.

These are single fired, glazed tiles that are usually only suitable for use on walls. They are made with softer glazes, and have a higher level of water absorption.

See Expansion Joints above.

HSE approved testing method used to ascertain the slip resistance of a floor. We explore all aspects of slip resistant tiles here.

This is an abrasion test standard, in use industry-wide, which rates the durability of a glazed tile. It is used to gauge the suitability of a tile to any given application. The Classes are usually stylised in Roman numerals. Class 0 are only suitable for walls, whereas Class V are suited to floors subjected to extensive traffic, such as in shopping centres. We cover PEI Ratings in detail and list the Class definitions here.

Ceramic tiles that have a water absorption rate of less than 0.5%. They can be either glazed or non-glazed. There is a misconception that "porcelain" refers to "polished porcelain", when in fact polished porcelain is unglazed, and buffed to a high sheen.

A liquid applied to the surface being tiled to ensure that the adhesive adheres correctly and creates a perfect bond. Some surfaces need a primer to seal them and prevent moisture from the adhesives absorbing. Other non-absorbent surfaces such as glazed tiles and well bonded paint need a primer to create a grip coat for the adhesive.

Tiles which are rectified have had their original edges ground off, such that each of the 4 new sides of the tile are at precisely 90° to the surface, and so that each tile in a batch is exactly the same size. We discuss rectified tiles, along with helpful images and video, here.

A score assigned to a tile by the manufacturer based on its slip resistance. The rating value is between 9 and 13, with the higher score reflecting better slip resistance. We detail out all the R ratings here.

This is a waterproof mastic used to seal joints, particularly in wet areas like bathrooms and kitchens.

This is the process of tile manufacturing where the glaze and clay are baked in the kiln at the same time.

These are plastic pieces that are used in installation to evenly separate tiles. They are manufactured in various thicknesses and shapes.

This is a method of waterproofing the area being tiled prior to installation. It is usually applied to the walls and floors in a shower or the surrounds of a bath. It protects against moisture penetration which can occur through tiles and grout, and will prevent water damage.

The trim is used on exterior corners to cover the exposed side of the tile. They are normally made from either plastic or chrome and matched to the colour of the grout and/or tile. They are available in several thickness to ensure the correct depth to match the tile.

A notched tool used to spread the adhesive to the surface being tiled. They come in a variety of sizes and thickness. The size of the trowel should match the size of the tile –you usually use a 4mm trowel for mosaic, 6mm and 8mm for small to medium size tiles, and 10mm and 12mm for large tiles and floors.

Any ceramic or porcelain tile is suitable for use with underfloor heating systems, whether they are electric or piped. When tiles are manufactured, they are brought to temperatures in excess of 800C, often up to 1,200C, so they will not be damaged by the heat emanating from the floor.

It is crucial, however, that flexible adhesive and grout is used.

The main cause of adhesive bond failure or tile cracking in this situation is movement or splitting of the concrete base or screed in which the pipes are embedded. The moisture level drops as they slowly cure, so the base shrinks slightly. This can be exacerbated by fluctuations in the temperature of the new heating system, which leads to failure of the tile installation.

A ceramic or porcelain tile which has not been covered with a protective glaze prior to or subsequent to being fired in a kiln. We discuss unglazed tiles in more detail here.