Technical Advice Note No. 2 FIXING WALL TILES

Glass wall tiles are available in various sizes and are normally used as a feature within areas of ceramic wall tiles, e.g. as a contrasting band or panel. There are currently no British or International Standards for the production or fixing of glass tiles. It is therefore important to seek advice at the design stage regarding the suitability for use and guidance on installation from the glass tile supplier.

1. Types of Glass Tiles

There are several types of glass tiles available and the appropriate conditions of use and the method of fixing will depend on how they are coloured. Two basic types of glass tiles are usually supplied:

• The tile is made from coloured glass (self -coloured). • The tile is made from clear glass and the underside has a coloured coating.

The colour on the underside of the tile may have been applied to the back surface and fired on as a vitreous glaze (colour-bonded), or may have been applied as a coloured coating such as a paint.

2. Installation

The glass tile suppliers should confirm which type of glass tile has been provided and the type and grade of tile adhesive that should be used to fix them to walls. The glass tile and the grade of tile adhesive used should be appropriate for the conditions of use. Where the glass tiles are installed on walls in wet or damp conditions some glass tiles with a paint or similar coloured coating on the underside may not be appropriate if the paint or coloured coatings are moisture sensitive.

Where the glass tiles are either of coloured glass, or have a vitreous glaze on the underside, it is normally appropriate to fix these to walls using a suitable Standard Set Class C2 S1 white ceramic tile adhesive. The glass tiles should be fixed into a straight ribbed adhesive bed with the underside of each glass tile pre-coated with a continuous layer of the white tile adhesive. This should ensure that no shading or variations in colour are visible on the face of the installed glass tile due to intermittent contact with adhesive ribs ‘grinning’ through.

Where the glass tiles have a coating such as paint on the underside of the tile then the selection of a suitable adhesive is difficult unless the glass tile suppliers can provide this information. If no information is available regarding a suitable adhesive then the use of either an epoxy resin based adhesive, e.g. a Class R1 or Class R2 adhesive, or an MS Polymer based mirror adhesive should be considered for fixing this type of glass tile to walls. When using a MS Polymer mirror adhesive, the adhesive should be applied directly to the coated back of the glass tile, not the

The Tile Association, 43 Stafford Road, Stone, Staffordshire ST15 0HG Email: [email protected] Website: www.tiles.org.uk Company registration: 3896624

surface of the wall. The tile should then be fixed to the wall. It may be necessary to carry out a trial adhesion test to verify compatibility between the coating and the resin based tile adhesive, or even with other types of tile adhesives.

It is important to select a grout that will not scratch the glass tiles. A fine smooth grout for narrow tile joints should be use. Grout a small test area first.

Some glass tiles may not be suitable for use in certain areas, for example, close to heat sources or wet areas. Advice on this aspect should be sought from the glass tile supplier as to the suitability of the glass tiles in question.

Larger format glass tiles can vary in size slightly and this should be considered at the design stage.

Refraction of Light

Refraction is defined as “The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different optical density.”

This is a phenomenon which can be highlighted when glass tiles are cut and becomes apparent after fixing.

British Standard BS8009-11 states that the “intensity of temporary lighting should be similar to that of the final permanent lighting”.

3.

Your TTA supplier should provide advice on how to tiles. a) Tiles that are 4mm or less than 4mm

To cut glass wall tiles that are 4mm thick or thinner, that do not have a painted-on colour backing, use a score-and-snap method.

Place the glass tile flat on a flat stable bench. Place the end of a glass cutter against the far edge of the tile and draw the cutter toward yourself while pressing down lightly on the glass. This will create a scored line in the glass. Place a thin piece of wire under the mark you scored. Position the tile so it balances on the wire along its score mark. Tip the tile so one edge rests on the table and exert pressure on the other edge until the tile snaps in half.

As alternative to a glass cutter you can use a tile wet fitted with a glass-cutting to cut any glass tiles, including thick tiles and those that have a painted color backing.

The Tile Association, 43 Stafford Road, Stone, Staffordshire ST15 0HG Email: [email protected] Website: www.tiles.org.uk Company registration: 3896624

Set the tile on the tray of the wet saw with the back of the tile facing up. If the tile has a coloured back, the white surface of the back of the tile will face up. Line up the area you want to cut with the blade of the saw. Slowly push the tile into the blade. Do not force the glass into the blade; the blade will pull it slightly in as it grinds through the glass as long as you exert a light, steady pressure on the back edge of the tile.

Cutting around sockets will require extra care. Mark or trace the cut size on the back of the tile. It is advisable to drill a hole at the point where the intersecting lines meet. This will prevent stress transferring through the tile. Carefully cut out the shape using a small grinder with a glass cutting blade.

Keep light pressure on the tile as the blade slowly cuts through the glass. When the glass is sliced through, turn off the blade before retrieving the pieces

When cutting glass tiles around socket outlets, light switches or plumbing fixtures etc, stresses are produced; this can cause the tile to break without apparent reason. In cases where cut outs cannot be avoided please make sure that the following points are considered:

• Electrical switch plate covers/lift call button or other fittings which are mounted to cover the face of the glass must be installed in a manner that does not exert any pressure on to the face of the glass. This can be achieved by applying a rubber gasket or over the fixing screws so that any pressure created as a result of fastening is carried through to the back box or substrate or applying a sleeve over the fastening screws. The sleeve should ideally be tubular and sized to a length that is just slightly proud of the face of the glass. • For circular cuts around pipes use a glass cutting core drill. b) Tiles that are 5mm or thicker

The surface of glass tiles is very hard and therefore the selection of is of the utmost importance (e.g. cutting wheels, angle approximately 155° is recommended, use cutting oils, to prevent the tools from being worn out and achieve a cleaner break). Maintain even pressure while cutting. 5mm wall tiles can be cut with hand cutters designed for glass. Cutting corners – Using a tipped - Drill a hole in the top of a corner sector first. It will prevent breakage during cutting and also prevent breakage later which could be caused by internal stress in glass. Grind all edges to remove any cracks that may have arisen. First grind the edges under the angle of 45° then gradually smooth out the surface. When grinding with grinding machine, use the drill equipped with disc. Use diamond abrasive pad or sharpening stone, both soaked in water. To drill holes in glass tiles use an electric drill with variable speed. Use only core drills for glass with a diamond surface, starting all drill holes at 45° to the tile and gradually straighten until drilling at 90° (straight).

The Tile Association, 43 Stafford Road, Stone, Staffordshire ST15 0HG Email: [email protected] Website: www.tiles.org.uk Company registration: 3896624

Drilling must be performed with a continuous water cooling system (i.e. hand held spray). If cooling is insufficient, the edges will crack or splinter off later. The larger the diameter of the hole to be drilled, the lower the speed should be set (e.g. 1800- 2000 rpm for Ø 10 mm, 800-1000 rpm for Ø 25 mm). If you perform pre-drilling from the rear side of the tile (approximately to one half), you will avoid splitting off the edges while finishing the drilling operation, this again must be water cooled as above. • Grind the edges as above. • Do not exert excessive pressure while drilling – allow the drill bit to do the work. • Tiles which have already been fixed can still be drilled providing the diameter of the drill bit is in the range 6 – 25 mm. Warning: the hole drilled into a tile should be greater by about 2 mm than any screw fixing to be used.

4. Grinding After cutting and drilling it is recommended that the installer should mechanically grind, smooth and bevel all exposed edges (e.g. by using a drill with a carborundum ). Use 60 grade or 100 grade Silicone Carbide paper or a Hand Pad. For edges and holes with an anticipated higher mechanical loading, finish grinding by using a grinding wheel made of nylon fibres with abrasive elements. Dipping the tile in water while sanding will provide the best results for sanding, smoothing and bevelling edges. The recommended grinding speed is 2000 – 3000 rpm when using an electric sanding disc. Continue grinding until the glass edge assumes a “milky” appearance, this effect reduces the visibility of jointing material through the tile edge and it also prevents potential cracking caused by incorrect or insufficient grinding of micro-cracks during the cutting process. Installing and attaching accessories to glass tiles: Prior to installing accessories, basins, mirrors, shower doors etc, ensure the adhesive and grout is fully cured. It is also important to select the correct anchor bolts, fixing screws and mounting brackets that are compatible with the tile and the substrate that you are mounting to (bricks, plasterboard, wood, etc.). The use of plastic bushes inserted through the body of the glass tiles is recommended, this eliminates any direct contact between fixing screws and the glass tile. Avoid over-tightening of the screws as this can cause tiles to crack.

5. Health and Safety

Extreme care will be required when cutting glass tiles. Protective goggles, safety gloves must be worn and appropriate cutting tools will be necessary.

The Tile Association, 43 Stafford Road, Stone, Staffordshire ST15 0HG Email: [email protected] Website: www.tiles.org.uk Company registration: 3896624