The correct installation of your natural stone tiles and the chosen material is of equal importance as choosing the product itself. This section provides only general information on fixing tiles, as it is impossible to provide a single guide due to the variety of factors which need to be considered, when specifying adhesives, grouts, sealants or other specialist ancillary materials for each of our natural stone products.
If you require a quotation then please furnish us with any necessary information so that we can provide the correct ancillary products. The information provided should be used in conjunction with a competent Stone or Porcelain installer, together with our recommended fixing and sealing products which are carried in stock.
- Stone tiles are often packed into crates very tightly, are wet at the point of production and may have residue from the various finishing processes employed. Therefore it is recommended that stone tiles are washed, either with clean water or a dilution of FilaCleaner and are allowed to dry completely before installation. They will often lighten in colour as they dry.
- Dry tiles are necessary prior to installation as any unusual tonal markings can be placed in less visible areas or used in cuts. At the point of installation always ensure that stone tiles are mixed to ensure consistency in distribution of any such variation. This will mean opening all crates or pallets of materials supplied.
- Minor damage such as edge chipping is often caused in packing or unpacking tiles, and should be expected, it is deemed normal practice for these to be used as cuts during the installation process.
- Tiling should start from the centre of the room and tiles should first be dry laid in order to avoid any unsightly cuts and to ascertain the optimum grout gap for your product.
- Uncalibrated stone tiles need to be graded prior to installation; the thicker tiles will dictate the floor level and should be installed first with thinner tiles being bedded up with an appropriate large format floor adhesive.
- Dimensions listed are nominal as slight variation in size and thickness can occur with most Stone, tiles as well as Stone Bathware.
- All backgrounds to be tiled to should be flat, level, clean, dry, free of dust, grease and any loose material and be as free of movement as possible.
- Make sure that you have discussed your requirements fully with your stone fixer and that they are familiar with the product to be fixed and your expectations.
- Lighting on site during installation should be as similar as possible to that in the finished project.
- All Stone, Terracotta, Ceramic & Porcelain tiles must be solidly bedded; cement or gypsum-based tile adhesives are the most appropriate for this method. Some travertine or large format tiles may have to be ‘buttered’ with adhesive on the back in order to ensure complete adhesive coverage.
- Tiles should occasionally be lifted during the laying process to ensure that sufficient compaction and full bed adhesion is being achieved.
- Fast setting adhesives are advisable in order that the moisture disperses quickly from the Stone or Terracotta. This helps to prevent various reactions that could be caused by the moisture retention of the tile.
- Light materials generally require fixing with white adhesives to prevent possible discolouration should the alkaline mortar bleed into, or react with the minerals within the body of the stone itself and also to prevent shadowing through to the associated light coloured grout.
- Flexible adhesives, combined with further substrate preparation, are required when the substrate is plywood, existing glazed tiles (floor application only), under floor and/or under tile heating is present or there is any degree of movement or instability in the substrate.
- For uncalibrated Stone tiles, the appropriate Large Format Flexible Floor Adhesive should be used to accommodate the variation in tile thickness. This will be most noticeable if laying a mix of sizes in an uncalibrated material.
- Cement based grouts are most appropriate for stone tile jointing. Stones with a textured surface tend to have grout joints of 6-10mm, whereas smoother Honed and Polished stones as well as Porcelain tiles can be jointed at about 3-5mm.
- Grout joints are in place to allow for any movement of tiles and should be a minimum of 3mm; it is not possible to ‘butt-joint’ tiles with the exception of Splitface materials which are designed to be fitted this way, although some grouting may be required dependant on the situation.
- The width of joint selected should be sufficient to accommodate any variation in tile sizes.
- When fixing a mix of sizes such as an opus pattern, the grout gap will vary in thickness due to the layout of the tiles in the pattern.
- ‘Slurry’ grouting with the appropriate colour of Flexible Wall & Floor Grout is necessary with unfilled Travertine and some Limestone in order to fill naturally occurring pits and crevices. Most other stones types and finishes including Honed, Polished, Brushed, Flamed and Riven materials as well as Porcelain should however be pointed in order to avoid grout residue being left on the surface of the tile.
- Any grout residue on the surface of the tiles should be wiped off as part of the grouting process and it is recommended to perform an intermediate wash with dilute FilaCleaner after grouting but before additional sealing.
- Where there is necessity for flexibility in the adhesive then a single part flexible grout should also be used.
- All stone and Terracotta tiles should have an initial sealant coat after fixing but prior to grouting as some tiles may absorb pigments from the cementitious grout.
- Heavily pigmented grouts may be subject to efflorescence as the salts which hold in the pigmentation are released as part of the drying process.
All substrates that are to be tiled to, be they floor or wall, should always be suitably prepared; they should be clean, flat, level, free from movement and free from anything which could be deleterious to adhesion. Correct identification of the substrate is vital to ensure the correct advice and ancillaries are provided. With the increasing use of large format & Splitface materials on walls, it is imperative to ensure that the substrate has a suitable weight bearing capability to accommodate the desired material.
WATERPROOFING – WET ROOMS
- Consideration should always be given to the type of material to be used in wet areas. Natural stone is composed of many different minerals, all of which will react with moisture in different ways. This means that, over time, some colour change may occur and this possibility should be accepted prior to ordering.
- Any stone or porcelain tile will not form a waterproof layer, therefore all tiled areas that will be subject to any amount of water ingress, such as shower enclosures or wet rooms, should have a waterproof substrate prior to fixing, to prevent damage from moisture. This process is called tanking and can be achieved with membranes, sealant adhesives and drainage systems.
- Water resistant adhesives and grouts should always be used and ideally the substrate should also be water resistant or waterproof. Even if tanking, use of substrate materials which are not water resistant or waterproof should be avoided wherever possible.
- Any fall required in a wet room should be incorporated in the substrate where possible, Schlüter have a range of preformed showerbases to help with this.
- If choosing a stone shower tray, due to the porous nature of stone, the area will need to be treated in the same manner as a wet room scenario.
MOVEMENT JOINT IN FLOORS
- Structural movement joints in the flooring and bed must be sited directly over and be continuous with any structural joints in the base structure.
- Perimeter movement joints are necessary where the flooring abuts restraining surfaces, such as perimeter walls, columns, kerbs, steps etc. These joints should always be installed unless the distance between walls is less than 2 metres.
- Intermediate movement joint requirements depend on the dimensions of the floor. In floors with less than 10 metres between perimeter joints, generally no intermediate movement joints are necessary, however they are required to divide larger areas, and these are normally placed at not more than 10 metres apart. Ideally, the distance between all joints (intermediate and perimeter) should be equal, unless other features of the installation dictate otherwise. Over potentially flexible type substrates and underfloor heating, areas without movement joints should not exceed 40m², with a maximum 8 metres between joints. Additionally movement joints should be placed directly over supporting walls or beams.
MOVEMENT JOINTS IN WALLS
- All existing movement joints in the substrate must be carried through to the finished surface with a surface movement joint positioned directly over background or plane changes within the substrate.
- Intermediate movement joints should be placed vertically at 4 metre centres and at internal corners and columns, etc.
- Horizontal movement joints should be positioned at floor and ceiling positions.