Natural stone varies in both appearance and application method compared with ceramic or porcelain tiles. Before you begin, it’s important to know the potential issues that you may face to ensure optimum preparation and application.
Jack Bottesch, product marketing manager for tile fixing from Saint-Gobain Weber, shares his top tips for tiling with natural stone.
Natural stone can offer a beautiful and authentic feel to your project but it’s important to be aware that not all natural stone have the same characteristics. Sandstone and limestone will be porous, granite and marble are quite dense, and slate could warp.
Before fixing the tiles, think about the colour of the adhesive as well as the colour of the stone. Darker coloured adhesive may show through light-coloured stones such as limestone and marble, making the stone appear darker once installed.
Choose the correct adhesive
Use an adhesive designed for natural stone. Tile adhesives that are highly polymer-modified to cope with flexibility are ideal for stones which undergo changes with temperature and humidity.
When applying adhesive there can be difficulty in achieving a level surface with natural stone due to a variation in thickness. Ensure a solid bed of adhesive with no voids when fixing. This will fully support the tile and prevent lines or rings from showing through as shadows.
Movement joints should be installed where tiling adjoins other materials, over existing movement joints or over junctions of different backgrounds where there is an increased chance of movement such as heating installations or strong sunshine.
Careful preparation before grouting
Natural stone tiles can be very porous or textured and because of this require careful preparation prior to grouting to stop damage occurring. Grout can also scratch soft glazed tiles and the surface of softer stone like marble.
Before grouting, ensure the tiles are clean and dry. If they need to be cleaned, use a pH neutral cleaner that won’t damage the surface of the stone. If there is a small amount of adhesive residue on the tiles, a specially formulated, higher pH cleaner may be needed.
Once the stone is clean, it needs to be prepared for grouting. To aid the removal of grout and to reduce the chance of staining, a suitable natural stone impregnator should be applied to the surface of the stone using a roller or sponge. This should be worked into the surface slowly to maximise effectiveness and to minimise frothing. After 4-6 hours the tiles should be dry enough to grout.
Many grouts available today are polymer-modified and can be very fine. While this offers better flexibility and increased strength it can also mean they are harder to remove from tiles and likely to stain natural stone.
To avoid “picture framing” or “tram lining” – when cement film has dried around the surface edge of a tile – bear in mind the below pointers when grouting:
Slurry grout the whole tile rather than point grout into the joints
Don’t leave excess grout on the tile for longer than the recommended time by the manufacturer as this can cause a chemical etch due to the pH level of the cement
Don’t use too much water
Once the grout is completely dry, another coat of natural stone impregnator should be applied over the tiles and grout. This should be repeated until all the surfaces are saturated and do not absorb any more impregnator.
Maintenance
Natural stone tiles will need regular maintenance to preserve their effectiveness and to keep them looking in tip-top condition.
General wear and tear can mean that natural stone loses its wow factor but with careful cleaning and maintenance, the beauty of natural stone can be kept for many years. Ensure the end user knows the correct cleaners and techniques to use to avoid damage. For regular cleaning, a neutral pH cleaner should be used and any products that contain wax should be avoided as this will spoil the appearance.
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