How to Install Outdoor Tiles
Over the last few years there has been a big increase in people using 20mm tiles for external tiling. But we also have noticed that customers are less aware of the methods used to install outdoor tiles, so here we run through the two main methods. The second method, which is using our tile adhesive is a far better option than using traditional sand and cement in terms of performance. The main benefit of using the adhesive, is that it is highly flexible and copes better in terms of expansion and contraction due to the extremes outside structures having to cope with.
- Tiling directly on to crush & run
In this first method, external paving is laid onto compacted crush & run aggregate and paving/tiles are laid in blobs of sand & cement motor. This is the traditional method that pavers used and have done so for many years but there are a number of flaws with this process especially when fitters adopt these methods with lighter tiles outdoors. As there is no damp-proof membrane (DMP) inserted into this system you cannot protect the fixing mortar and tiles from moisture rising up from beneath. Over time, when freeze thaw sets in in the winter, you start to see tiles debonding from the mortar and cracking. The other big issue here is that large blobs leave voids under tiles where water will naturally fill over time. When the winter comes the fixing mortar will be put under extreme pressure and inevitably the debonding process will begin. The same fixing process should be adopted for external tiling as internal, where we recommend a full bed fixing method is adopted. This is where you comb a full bed of adhesive on the floor, back butter the tile or paving and press into the adhesive, ensuring that there are no voids below the tile. No special product is required when using any of our adhesives, you just need to make sure that the fixer back butters the tile with the adhesive. Even though we will not guarantee the above system, using our adhesive in the fixing process over traditional sand & cement mortar, will have far better results than not using any adhesive at all.
- Using our adhesive under the screed:
All surfaces must be clean, firm, dry, free from all loose matter including dust, dirt, oil, grease, laitance and any other contaminants that may affect adhesion. All substrates should be prepared to provide a rigid and secure base without deflection and suitable to support the intended weight. Lay a suitable damp-proof membrane (DPM) such as black visqueen on the ground and then the relevant screed (either sand & cement or concrete) needs be applied / poured.
The following information provides further details for preparing various common substrates. Unless stated otherwise, any reference to the term “diluted” means 1 part primer mixed with 1-part clean water.
Concrete Screeds: Prime with 2 diluted coats of ROCATEX Acrylic Primer or 1 diluted coat of ROCATEX Ultimate Grip Primer. Substrate curing before tiling can commence is approximately 6 weeks.
If the screed has not yet fully cured and there is no standing water on it, you can fix the tiles with either of our S2 tile adhesives, but you do not prime the substrate. For external tiling of this type and size I recommend the use of either Dural Ci++ or Alfa Pro matting and all joints and the perimeters need to be sealed with the waterproofing tapes, which can also be applied if the screed has not yet fully cured. This can be fixed with any of our S1 tile adhesives and again no priming is required. Using this matting will waterproof the structure from both positive and negative water pressure and it will also assist the tiling structure in dealing with the extremes you get in terms of expansion and contraction externally. The DMP under the screed will stop rising damp/water and this matting on top of the screed will protect the tiling structure from above and below.
British standards state that expansion joints should be inserted every 8 meters of tiling length but externally we state every 3 meters and perimeter joints should also be used if the floor borders any building/wall structures. We can supply expansion joints colour matched to our grouts both cement-based and epoxy. Grout widths will need to be at a minimum of 3mm-5mm. Externally we would recommend the use of epoxy grout as this will help waterproof the structure and is far more durable than a cement-based alternative.
Mix 20kg of ROCATEX S1 or S2 tile adhesives in a clean mixing vessel with between 4.8 - 5 litres of cold clean tap water until a smooth creamy consistency is achieved using a suitable drill with the whisk attachment. Mix at a slow speed for a minimum of 2 minutes to ensure that all ingredients (polymers, retarding agents etc.) are dispersed thoroughly throughout the whole mix.
The mixed adhesive is applied to the prepared surface and then combed through with a suitably sized notched trowel to create a ribbed adhesive bed. The tiles should be pressed into place with a twisting and sliding action to achieve full adhesive to tile transfer.
When tiling to floors and all external situations, or in wet areas such as showers and swimming pools, or when fixing granite and quartz, solid bed fixing should be achieved. To achieve a solid bed requires the tiles to be buttered immediately prior to placing into the ribbed bed so no voids are left beneath the tiles. The size of the notched trowel chosen depends on the size of the tile, the surface being tiled, the profile on the back of the tile and the degree of coverage area required.
Expansion joints must be installed in accordance with the relevant Part of BS 5385. Test open time by touching the adhesive bed with a finger; if the adhesive transfers to the finger a safe bond is assured, if not, the adhesive must be removed and replaced with fresh material.
*Never add water or powder to a mix that has begun to set. Do not apply at substrate temperatures below 5°C or in conditions of extreme heat. Exterior installations must be protected from direct sunlight, wind or rain.
Tile protection prior to grouting: sealing
20mm external porcelain tiles are slip resistant therefore they are slightly pitted/textured so they need protecting, to reduce the chances of the fitter filling these voids with grouting material (mortar, brush in resins, grout both cement based and epoxy) and not being able to remove the excess. Prior to grouting, we recommend applying 1 coat of C-10 Ultimate water-based sealer which will be a sacrificial coat to reduce the chance of any grouting material been left in the surface of the tile.
Shake the bottle before use and ensure surface to be treated is completely clean, dry and free from dirt, grime, cement and grout. If necessary, first wash the surface with a dilute solution of ROCATEX Tile & Stone Renovator 1:10. Rinse well to remove residues and leave to dry. It is important to remove any factory-applied sealer or wax from the surface of porcelain before sealing.
Porcelain Tiles: Apply this sealer generously using ROCATEX Sealer Applicator or sponge, brush, roller, paint pad and remove any excess solution after 15-30 minutes. Do not grout until 4 hours after applying the sealer.
Natural Stone / Paving: Apply this sealer generously using ROCATEX Sealer Applicator or sponge, brush, roller, paint pad or spray applicator and remove any excess solution after 15-30 minutes. A second application is recommended after 1 hour to ensure complete coverage and again remove any excess solution after 15-30 minutes.
Treated areas should be dry enough to walk on after about 1 hour but will take 72 hours to become fully resistant which is required for protecting natural stone products. During this time DO NOT cover the surface and wipe up any spills immediately. Consideration should also be given to any moisture trapped in a surface on newly laid floors in terms of covering the surface after sealer application.
To check that the surface has been adequately sealed, a simple water bead test can be performed. Apply a teaspoon spoon of water onto the sealed surface and leave for 15 minutes, if the bead is absorbed then another coat is required.
*Do not apply in direct sunlight or in temperatures exceeding 25°C. Do not grout until 4 hours after applying the sealer. Tip: Without prior experience or in cases of doubt, try the product in an inconspicuous area prior to use.
In terms of grout, we will guarantee both our cement-based grout and epoxy. The epoxy is the absolute belts and braces option because; it will not allow any water to pass through it and protect the system, it can cope with greater expansion & contraction than the cement-based option and its appearance will last the test of time.
Grouting (RG1 Ultimate Epoxy Grout)
The joints must be clean, free of dust and free from adhesive to at least 2/3 of the thickness of the tiles. Any adhesive or mortar which has seeped into the joints whilst laying the tiles must be removed whilst still fresh. Ensure the adhesive has set and most of the moisture has been lost. ROCATEX RG1 Ultimate Epoxy Grout is not harmed by damp from the base but the joints must not be wet when grouting.
Add the curing agent (PART B) to the pigmented epoxy resin (PART A) and mix thoroughly until a uniform colour is achieved. Pour the mixed liquid into the larger mixing bucket and slowly add the filler aggregate (PART C) and continue to mix for 3-4 minutes until a uniform consistency has been achieved. Use a slow-speed electric mixer to guarantee perfect blending and to avoid overheating of the mix which could reduce working times.
Apply the grout by using a hard rubber grout float or squeegee, ensuring that the joints are completely filled. Tile spacers must be removed from all joints. Remove any excess grout (this can be done with the edge of the same float) and clean the tile surface with a fine-textured sponge or white emulsifying pad dampened with water. Do not over wet the sponge/pad and pass over the tiles at 45° to avoid removing grout from the joint. Rinse the sponge/pad often with clean water and replace it when it becomes too impregnated with resin. Within 24 hours of grouting, any remaining haze can be removed with a white emulsifying pad. The tiles should not be subjected to normal service conditions until the grout has cured, usually 24 - 48 hours depending on the temperatures applied. Do not apply if frost is forecast within 24 hours, in wet conditions, in temperatures below 8°C or above 30°C, to areas in direct sunlight or to substrates that are hot.
Once hardened, epoxy grouts are very difficult to remove, therefore, care must be taken to remove all traces of grout from the surface of tiles before the grout has cured. Textured porcelain tiles should first be protected with ROCATEX C-10 Ultimate Sealer which is an effective water-based pre-grout treatment for use on all types of textured porcelain tiles, both internally and externally. It helps with grout and jointing compound release from rough-textured surfaces. When using pigmented grouts, it is advisable to carry out initial tests to ensure that staining on the tiles does not occur, especially those with textured surfaces, matt glazes, unglazed or quarry tiles. Apply the grout to a few tiles before fixing to check for any staining and ease of cleaning off.
Grouting (CG2 WA Ultimate Grout)
Mix 5kg of ROCATEX CG2 WA Ultimate Grout with approximately 1.6 litres of cold clean tap water until a smooth creamy consistency is achieved using a suitable drill with whisk attachment. Mix at a slow speed for a minimum of 2 minutes to ensure that all ingredients (polymers, retarding agents, colour pigments etc.) are dispersed thoroughly throughout the whole mix. Allow to stand for 2 minutes then re-mix.
Use a suitable grout float or squeegee to work the grout deeply into the joints ensuring the joints are completely filled. Excess grout should be removed as work proceeds and any residues left on the tile face can be removed by wiping off with a damp sponge approximately 20 minutes after application. Any dry film remaining on the surface can be removed by polishing off with a dry cloth when the grout has hardened in the joints.
Do not apply if frost is forecast within 24 hours, in wet conditions, in temperatures below 5°C or above 25°C, to areas in direct sunlight or to substrates that are hot.
When using the cement-based grout, we also recommend you seal this with a coat of sealer when it is dry to help protect from the elements. We are in the process rolling out a “Porcelain Protect Sealer” for the external market but it is just the C-10 in a different bottle.