We know you can have questions about our products. Our Technical Services team have advised on thousands of them, and you can find answers to the more common queries here. For the latest technical or health and safety data on all ARDEX products, consult the relevant technical or health and safety datasheet on our product pages.
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NOTE: In addition to our guidance on this page, tiles should be installed in accordance with the relevant parts of BS 5385 and BS 8000: Part 11 Workmanship on Building Sites.
Tiling to Specific Substrates
How do I tile to anhydrite screeds?
After confirming it is dry, abrade the surface with suitable mechanised equipment to remove any laitance, loose debris and dust, and reveal the aggregate underneath.
The anhydrite screed should then be primed with a single coat of ARDEX P 51 diluted 1:3 with water, applied in one continuous coat using a brush or broom. Once the ARDEX P 51 is dry, tile as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile to gypsum floorboards?
Before tiling to gypsum (or calcium sulphate) floorboards, they must first be primed with a single coat of ARDEX P 51 diluted 1:3 with water, applied in one continuous coat using a brush or broom. Once the ARDEX P 51 is dry, it can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile to bitumen adhesive residues?
How do I tile to asphalt?*
*Internal, dry areas only
Before tiling to asphalt*, check to ensure it has an adequately adhered sand keyed surface. If it is in good condition and is well adhered, it can be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive. If however the sand key is poor or worn away, it should first be primed with ARDEX P 82. Once the ARDEX P 82 is dry, tile as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I level over sand and cement screeds and concrete?
Sand and cement screeds and concrete can be highly porous and absorb moisture from subsequently applied levelling compounds, which reduces their flow properties.
Before levelling over sand and cement screeds and concrete, prime with single coat of ARDEX P 51 diluted 1:3 with water for sand and cement screeds or 1:2 for concrete and applied with a brush or broom. Once the ARDEX P 51 is dry, it can be levelled with an appropriate ARDEX Levelling Compound and then tiled with an ARDEX Cement-Based Tile Adhesive.
How do I tile to existing tiles?
If levelling isn’t required, prime existing tiles with a single coat of ARDEX P 4 applied with a short pile roller or paint brush. It will dry after 30-60 minutes, producing a textured-grip surface which can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
If levelling is required on floors, level over existing tiles with ARDITEX NA applied 3mm+ deep direct (without priming). It will dry in as little as 3 hours, and can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile to fibreglass?
How do I tile to plaster?
How do I tile to plywood floors?
If levelling isn’t required, prime plywood floors with a single coat of undiluted ARDEX P 51 applied with a brush or broom. Once the ARDEX P 51 is dry, it should then be tiled using an ARDEX RAPIDRY FORMULA adhesive such as ARDEX MICROTEC X 7001, ARDEX MICROTEC S 27 or ARDEX MICROTEC S 28.
If levelling is required, level over the plywood with ARDITEX NA applied direct (without priming). It will dry after 3 hours and should then be oversheeted with a suitable mechanically fixed tile backer board, which can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile to plywood walls?
Tiling to plywood walls is no longer recommended under BS 5385-1:2018. Plywood walls should be oversheeted with tile backer board or plasterboard as appropriate for the intended area, and these can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile to steel?
To tile steel in internal and external locations, including wet areas, use ARDEX X 60 PU FLEX applied direct (without priming). It will dry in 3 hours and can then be grouted using an appropriate ARDEX Tile Grout.
How do I tile to painted substrates?
Before tiling to painted substrates, the paint should be removed using suitable mechanised equipment to reveal the substrate underneath and prevent any barriers to adhesion. The substrate can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile to uncoupling membranes?
Uncoupling membranes with cavities can be pre-filled to produce a flat surface ideal for tiling. For this application, smooth over the uncoupling matting with ARDITEX NA up to the top of the cavities using a smoothing trowel. ARDITEX NA can be applied thicker if additional levelling is required, but along with the subsequent tile adhesive application, the depth should not exceed 10mm. ARDITEX NA will dry in as little as 3 hours and can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
How do I make uneven walls flat before tiling?
How do I fill holes before tiling?
What are the maximum weight restrictions for wall tiling?
As per BS 5385, the maximum weight restrictions for wall substrates are:
Gypsum plaster: 20kg/m2
Gypsum plasterboard (12.5mm thickness): 32kg/m2
Sand and cement rendering: Generally no restrictions
Lightweight foam-cored tile backer boards: 60kg/m2
Glass reinforced cement-based boards: 50kg/m2
Gypsum fibreboards: 40kg/m2
Other rigid tile backer boards: Consult manufacturer
Why do I need to wait so long before tiling to certain substrates?
As per BS 5385, the following drying times should be allowed before tiling:
Concrete: at least 6 weeks
Traditional sand and cement screeds: at least 3 weeks
Traditional sand and cement renders: at least 2 weeks
Plaster: at least 4 weeks
These backgrounds shrink as they dry; to avoid the risk of debonding, tiles should be fixed after these times.
Alternatively, drying times can be significantly reduced when ARDEX Screed Cements and Renders are used in the construction process. For example, ARDEX AM 100 Render can be tiled after 2 hours and ARDEX A 38 Screed after 4 hours!
When should I commission underfloor heating?
How do I tile to heated sand and cement screeds?
Before tiling to heated sand and cement screeds, you must first ensure the underfloor heating has been commissioned. As per BS 5385-3, traditional sand and cement screeds should be at least 21 days old, at which point the underfloor heating can be increased by 5⁰C every day until the maximum water temperature advised by the underfloor heating manufacturer is reached; commissioning can begin much sooner with an ARDEX Screed, in as little as 3 days. The underfloor heating should then be turned off for approximately 24 hours to allow the screed to cool down to room temperature. If site conditions are cool, maintain the screed and room temperature at 15⁰C or just above by adjusting the heat input accordingly. It can then be tiled as normal using the appropriate ARDEX Cement-Based Tile Adhesive.
How do I tile over electric underfloor heating systems?
How do I prepare a concrete base before tiling a patio area?
The preparation required is dependent on the depth of screed and/or levelling compound required in order to make up the necessary levels and/or falls (which typically range from 1/35 to 1/80):
• Where just a thin smoothing layer of 2-20mm is required, firstly use suitable mechanised equipment to remove any contamination and reveal the aggregate underneath. It should then be levelled with a suitable external levelling compound such as ARDEX K 301.
Once the screed and/or levelling compound is dry, tile as normal using the appropriate ARDEX Cement-Based Tile Adhesive.
How do I waterproof or tank bathrooms, showers and other wet areas* before tiling?
*Does not include swimming pools
Wet areas should be waterproofed before tiling using ARDEX WPC to protect moisture-sensitive backgrounds behind the tiles, and also prevent moisture-ingress into adjacent rooms. Holes, gaps and joints should be waterproofed using a slump-free mix (MIX ONE) applied with a trowel, which will dry in approximately 1 hour. Overall surface waterproofing can then be achieved with two coats of a flowing/paintable mix (MIX TWO) applied with a paint roller or brush, with 30 minutes allowed between each coat. The second coat will dry in approximately 60 minutes, and can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
Why should I waterproof or tank bathrooms, showers and other wet areas* before tiling?
*Does not include swimming pools
The underlying substrate in wet areas, or substrates adjoining wet areas, is often moisture-sensitive e.g. plaster, plasterboard and even some proprietary tile backer boards. Even when they’re tiled, water can still get to the background through cementitious grout joints and adhesive bedding, as they’re porous in nature and allow moisture to be absorbed through them. Ultimately, this results in damp and mould; and over time, it can transfer to adjoining rooms and/or cause the tiles to de-bond. As recommended by BS 5385-1: 2018 and BS 5385-4: 2015, ensure wet areas in both domestic and commercial installations are waterproofed (we recommend ARDEX WPC) to prevent unsightly and costly water damage.
How do I waterproof plywood floors before tiling?
To waterproof plywood floors before tiling, install an appropriate waterproof uncoupling mat or waterproof tile backer board. They can then be tiled as normal using an appropriate ARDEX Cement-Based Tile Adhesive.
Using Tile Adhesives
Can I use ready-mixed tile adhesives to fix large format tiles?
Ready-mixed tile adhesives should only be used to fix mosaics and ceramics up to 300mm x 300mm or porcelain up to 150mm x 150mm. Today’s popular large format tiles can measure 600mm x 300mm or bigger, so ready-mixed tile adhesives should not be used to fix them. Instead, use an appropriate ARDEX Cement-Based Tile Adhesive.
Which adhesive should I use to install large format tiles?
Large format tiles must be solid bed fixed in accordance with BS 5385. To ensure you’re achieving solid bed fixing on large format floor tiles, use a semi-pourable or pourable tile adhesive such as ARDEX X 7 R, ARDEX MICROTEC X 78 or ARDEX MICROTEC X 7001. To ensure you’re achieving solid bed fixing with a slump-free adhesive, ARDEX X 7 or ARDEX MICROTEC X 77 for example, back buttering is usually required.
Can I use ready-mixed tile adhesive to fix floor tiles?
Ready-mixed tile adhesives should only be used to fix wall tiles. Floor tiles should be fixed with an appropriate ARDEX Cement-Based Tile Adhesive.
How do I fix mesh-backed porcelain tiles?
According to The Tile Association, it is the tile manufacturer or supplier that must take responsibility for ensuring their mesh-backed porcelain tile is fit for purpose, and for specifying a compatible class of tile adhesive for their product, as classified in BS EN 12004. Please consult the tile manufacturer/supplier for further guidance.
How do I stop large format tiles slipping down the wall?
Today’s large format tiles are not only heavy, but also very dense and can have flat undersides too, making it more difficult for traditional adhesives to grab them. To stop your tiles slipping, fix them with an advanced slip-resistant tile adhesive. ARDEX MICROTEC X 77 for example achieves double the European Standard for slip resistance and can be used to fit all tile sizes without slipping (consideration must still be given to the BS 5385 fixing guidance e.g. when fixing tiles at height).
How can I reduce tile adhesive waste?
With standard tile adhesives, you may find there’s not enough time to cut and install your tiles, and so you must remove your applied adhesive and replace it with freshly mixed material; or your adhesive has simply gone off in your bucket and you need to throw it away and mix a fresh batch. This is particularly common in summer, with higher temperatures causing them to skin over much quicker. To reduce waste of skinned over tile adhesive, use one with an extended pot life and open time for better longevity from the very outset. ARDEX MICROTEC X 77 for example has a pot life of 3 hours and an open time of 60 minutes!
How do I prolong the open time of my tile adhesive?
When tiling to sand and cement screeds and concrete, the substrate can be dampened with water using a mist sprayer. This will reduce suction from the substrate, and help maintain the open time of all ARDEX Cement-Based Tile Adhesives.
How do I achieve solid bed fixing?
Under BS 5385, solid bed fixing must be achieved for: all floor tiling; wall tiling with tiles greater than 0.1m2 (316mm x 316mm); and all tiling in all wet, external or swimming pool locations. To ensure you’re achieving solid bed fixing on floor tiles, use a semi-pourable or pourable tile adhesive such as ARDEX X 7 R, ARDEX MICROTEC X 78 or ARDEX MICROTEC X 7001. To ensure you’re achieving solid bed fixing on walls, or when using a slump-free adhesive on floors, back buttering is usually required.
How do I stick down uncoupling membranes?
To stick down uncoupling membranes such as those by Schluter and Dural, use ARDEX AF 200 PLUS. It is ready-mixed and can be applied using a B1 or 2mm x 6mm v-shaped notch trowel direct (without priming) to plywood, floorboards and dry concrete, as well heated and unheated sand and cement screeds and levelling compounds. After 5-10 minutes, the matting can be installed and then tiled or levelled immediately using an appropriate ARDEX Cement-Based Tile Adhesive or ARDEX Levelling Compound.
How do I stick uncoupling mats to anhydrite screeds and gypsum floorboards?
Before sticking an uncoupling mat to an anyhrite (or gypsum or calcium sulphate) screed, you must first ensure it is dry and suitably prepared; please refer to our How do I tile to anhydrite screeds? FAQ for further guidance. In the case of both anhydite screeds and gypsum floorboards, they must then be primed with a single coat of ARDEX P 51 diluted 1:3 with water, applied in one continuous coat using a brush or broom. Once the ARDEX P 51 is dry, the uncoupling mat should then be fixed using ARDEX AF 200 PLUS or the appropriate ARDEX Cement-Based Tile Adhesive.
What is the difference between pot life, working time, open time and adjustment time?
Pot life is also known working time, and they both refer to the length of time that the mixed mortar remains usable and workable inside the pot/bucket after it has been mixed.
Open time is the length of time that tile adhesive ribs remain wet and able to receive tiles (before skinning over) after being spread onto the wall or floor.
Adjustment time is the amount of time in which a tile can adjusted or moved after it has been fixed into the freshly applied tile adhesive.
Using Tile Grouts
Which tile grout should I use?
In general, cement-based tile grouts are the most commonly used and are suitable for the vast majority of applications. ARDEX-FLEX Flexible Tile Grouts can be used with almost all tile types including non-moisture-sensitive natural stone and come in 35 different colours to suit any installation; use ARDEX-FLEX FS for joints up to 4mm wide or ARDEX-FLEX FL for joints 3-15mm wide.
For areas where chemically resistant or waterproof joints are required, or where the client is looking for a reduced maintenance schedule by minimising the build up of dirt, fungi and mould, opt for an easy-to-apply epoxy grout such as ARDEX EG 8 PLUS.
When installing moisture-sensitive natural stone, use ARDEX MG, our RAPIDRY Technology tile grout which helps to eliminate the risk of water staining and warping.
How do I avoid colour streaking in tile grouts?
How do I prevent my tile grout going mouldy?
Where a cement-based tile grout has already been used, mould build-up can be reduced by maintaining a regular cleaning regime. To minimise mould and bacteria growth from the outset, opt for an easy-to-apply epoxy resin grout such as ARDEX EG 8 PLUS; it creates impervious joints, making it much more resistant to fungi, mould and bacteria than traditional cement-based tile grouts.
How do I stop efflorescence?
Efflorescence is a naturally occurring and well-documented issue, affecting many cement-based products (not just tile grouts) due to their water and soluble lime content. It happens during the drying phase, with the soluble lime depositing on the surface as a dry white powder as the water evaporates. In tiling, the moisture can come from the tile grout, adhesive bed, underlying substrate and even the atmospheric conditions of the room!
Efflorescence is aggravated by excessively damp conditions after installation and by prolonged delays in drying out. The modern trend of large format tiles means there are now fewer grout joints over the tiled area and drying is slowed; it is therefore not unexpected for efflorescence to occur.
Efflorescence cannot be avoided; however, steps can be taken so as not to exacerbate the problem: 1) Do not exceed the water requirements of the tile grout 2) Do not use excessive water during cleaning down and 3) Warm and dry conditions following installation will assist the drying process.
Fortunately, where you do experience efflorescence, it can be removed easily using an appropriate proprietary cleaner designed for this purpose.
Why has my tile grout turned white and how do I stop it?
The most likely cause of a tile grout turning white is efflorescence, which is a naturally occurring and well-documented issue affecting many cement-based products. For information on how to minimise or remove efflorescence, please refer to our How do I stop efflorescence? FAQ.
How do I ensure a tile grout colour will complement a tile?
Tile grouts can have a significant impact on the resulting aesthetic of both the tiles and the room. The ARDEX-FLEX Tile Grout range is available in 35 colours to suit any installation; and whether you’re looking to complement or contrast with the tiles, free colour stick samples can be ordered online so you can test the look before purchasing.
How do I make it easier to clean off epoxy tile grout residues?
Traditional epoxy tile grouts can quickly stick to the tile face, and as a result many tilers clean them off too early to prevent this from happening, which often results in some of the soft grout mortar coming out of the joints. Alternatively, ARDEX EG 8 PLUS Epoxide Tile Grout can be left on the tile surface for up to 60 minutes, allowing the grout to harden adequately, and can still be cleaned off with a normal sponge! For best results, use a fine mist spray to soften the residues first.
Using Silicone Sealants
How do I prevent my silicone sealant going mouldy?
To prevent mould growth in silicone sealants, use one that contains a fungicide such as ARDEX ST.
Fixing Natural Stone
How do I fix and grout natural stone tiles?
The main issue associated with fixing natural stone is determining if they’re moisture-sensitive or not and, following that, using the correct products to fix them. If the stone is moisture-sensitive, moisture from traditional adhesives and grouts can migrate into the stone and cause discolouration, staining and even warping. If you’re fixing moisture-sensitive stone, or if you’re unsure, use an ARDEX Natural Stone Tile Adhesive and ARDEX MG Tile Grout. These products incorporate ARDEX RAPIDRY FORMULA Technology to ‘lock’ the mix water within the mortar and eliminate the risk of water staining. The installation should then be finished with ARDEX ST Silicone Sealant.
How do I fix mesh-backed natural stone tiles?
As per BS 5385, the mesh-backing on a stone wall tile must be removed, e.g. using a grinder, so that no more than 25% of its back is covered with the mesh; if the mesh cannot be removed, the stone should be mechanically fixed. With mesh-backed stone floor tiles, all of the mesh backing must be removed. The tiles can then be fixed using the appropriate ARDEX Natural Stone Tile Adhesive.
How do I fix granite and other heavy stone floor tiles in a patio area?
Before tiling a patio area, the concrete base should be prepared; please refer to our How do I prepare a concrete base before tiling a patio area? FAQ for further information. The tiles should then be fixed using ARDEX X 32 which can be applied 3-30mm thick, making it ideal for thick bed applications and for uncalibrated stone.