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Prepared tiles on backerboard ready for a coloured grout demonstration
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Knowledge Centre

Grout & Epoxy

Learn all you need to know about grout & epoxy here.

To access other topics in the Knowledge Centre, click the book icon below.

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Prepared tiles on backerboard ready for a coloured grout demonstration
Installing Grout & Epoxy
How wide can a grout joint be?

Most grouts will go up to 20mm wide - this tends to be the maximum for a grout joint width. Beyond this, the grout would become structurally weaker and possibly crack or break up.

What is the narrowest grout joint for wall or floor tiling?

The narrowest grout joint for wall tiling (according to British standards) is 2mm and the narrowest grout joint for floor tiling is 3mm.

The reason for this is if any movement occurs within the tiling, the joint will cope with it as long as the movement is limited. If the tiles are closer together or butted up the movement would likely cause the installation to fail/ cause cracks.

If you are matching wall and floor tiles (i.e lining them up) you would need a minimum joint of 3mm throughout the installation (i.e wall joints 3mm to match the floor joints).

What consistency should the grout be?

All grout packaging comes with a mixing ratio on the reverse - seldom do people read these instructions and often this is the cause of grout failure. Check the packaging as it should be a smooth workable paste without too much or too little water.

Epoxy is easy to mix as there is a part A and a part B which are simply mixed together in the quantities provided.

How do I stop the grout drying too quickly in the joints?

If you find the grout is drying very quickly in the joints this may be due to a porous ceramic, or similar tile, sucking the moisture from the grout and preventing it from naturally drying.

If this is the case, then a slight wetting of the joints prior to grouting will help, but do not overwet as this will weaken the grout.

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Epoxy Grout
What is the best tool to apply grout?

The best tool for applying grout is a grout float (squeegee); it is a handled trowel with a flat rubber base that does not mark the tiles. Pressure can be applied to ensure the grout is fully applied into the joint and the grout float can be dragged along the surface of the tiles at a 45-degree angle to remove the excess. When applying grout, it is better to use a grout float with no metal as some have a metal layer above the rubber and sponge base that can mark walls when grouting in corners. A grout float with a plastic layer and then a hard rubber is better.

What is the best tool to apply epoxy grout?

Similar to applying cement-based grout, a grout float (a specially designed ‘squeegee’) with a much firmer, thinner rubber layer is best suited for applying epoxy grout. Apply pressure to the grout to ensure a good application and then drag the squeegee at a 45-degree angle across the tiles to remove any excess. A normal float can also be used but is not as well designed for this purpose.

What is the best way to wash off cement-based grout?

The best tool for applying grout is a grout float (squeegee); it is a handled trowel with a flat rubber base that does not mark the tiles. Pressure can be applied to ensure the grout is fully applied into the joint and the grout float can be dragged along the surface of the tiles at a 45-degree angle to remove the excess. When applying grout, it is better to use a grout float with no metal as some have a metal layer above the rubber and sponge base that can mark walls when grouting in corners. A grout float with a plastic layer and then a hard rubber is better.

What is the best way to wash off epoxy grout?

Epoxy grout is best washed off using either an epoxy sponge (a coarse sponge that has larger holes to prevent clogging) or by using a white emulsifying pad (a white, non-marking, fine and soft scouring pad) with water within 30 mins of application. You will generally require at least one sponge or pad per m2. If the epoxy has left streaks or hazes that are still visible after 24hrs, you will need specific chemicals to remove any residue as it will have hardened. Certain manufacturers will provide these chemicals for removing the epoxy film which can be used up to 7 days after application. As a last resort, if the epoxy has been set for longer than 7 days, different chemicals are required for removing the excess epoxy - the epoxy manufacturer may also provide these chemicals. Be sure to use the correct cleaner if you have been provided with both 24hr+ and 7 days+ products. It would be wise to check with your supplier and only attempt to apply the epoxy grout if you are confident in your abilities and knowledge of the method required.

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How long does it take for the grout to dry?

This can vary from 3 hours to 72 hours depending on the grout used. Rapid cementitious grouts are readily available although epoxy grouts will take 3 days to build mechanical resistance, and up to 7 days to build chemical resistance.

How long should I leave newly grouted tiles before cleaning?

After the buffing off of the tiles during the final stages of grouting (ensuring all traces of grout dust are removed), the grout should be left for a minimum of 72 hours before cleaning with any form of chemicals. Epoxy should be cleaned the next day, if required, with a manufacturer-approved product and then left for 7 days before cleaning with chemical-based cleaners.

How can I remove dried grout from the surface of my tiles?

To remove dried grout, you will first need to know the type of grout used and, more importantly, the material of the tile, as this will inform which cleaning product you will need. For instance, some grouts will require an alkaline-based solution to break down the polymers, whereas others will need an acid-based solution. Stone and certain softer tile materials will not take an acid-based cleaner due to the acid etching the surface, so advice will need to be taken if stone is involved. Epoxy grouts will have their own products to enable the removal of grout build-up. With any solution, it is always best to try this in an inconspicuous area before applying liberally. Your supplier or chemical manufacturer should be able to offer advice in this regard.

Learn more about Kerakoll Grout.

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Will the grout stain my tiles?

Possibly. Depending on the type of tile and texture, the grout could potentially stain your tile or hold in a roughly textured tile. 

If we take these two possibilities separately and look at the staining first, here are three ways to minimise or prevent this from happening. 


  1. Seal your tiles if they are porous or if the manufacturer recommends a sealer before grouting.

  2. Some manufacturers only recommend white grout to avoid the appearance of stains on the tiles. Always check the information that comes on your tile’s packaging or any information given as a handout at the time of purchase.

  3. Try the grout on an off-cut of tile before using it on the tiles that are fixed.

For rough textured tiles, you can use a temporary sealer that enables you to wash off the grout (and the sealer) without staining the tiles. It is worth mentioning that Kerakoll provides a grout with lozenge-shaped polymers, rather than the conventional spherical shape, to reduce grout settling in the imperfections of the tile’s surface, thus aiding in preventing stains. This is accomplished due to the lozenge shape protruding from the tiny cavities in the texture of the tile, which are easily dislodged when cleaning, unlike spheres. Spherical polymers can fit more compactly within cavities and spin rather than dislodging, making it harder to prevent stains.

A traditional spired modern kitchen with authentic natural stone tiles
How do I grout rough textured tiles without staining them?

For roughly textured tiles you could use a temporary sealer that enables you to grout without staining the tiles. The sealer is applied before grouting and removed during the washing process. 

There is a grout on the market (Kerakoll Fugabella Color) that has changed its polymers to a lozenge shape, as this shape effectively protrudes out of the small cavities within the surface as opposed to a spherical shape which stays in the cavity and just spins without dislodging when the sponge is wiped over it. The lozenge shape prevents the tiles from staining due to the grout not actively holding in the surface of the tile. 

Do I need to seal my tiles before grouting?

Some tiles will require sealing prior to grouting whilst others will not. It is best to seek advice and check with the manufacturer. Below is a list, although not exhaustive, that highlights some of the more common materials that would be required before sealing.

Crackle glaze tiles, polished porcelain, some matt porcelain, polished stone including marble, stone including amongst others limestone, marble, travertine, shist, sandstone, slate and basalt, encaustic, quarry tiles, terracotta tiles, quartz and quartz conglomerate tiles and Mosaics with stone in will all generally require sealing prior to grouting.
If in doubt, check! As mistakes can be costly.

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Can I seal my grout?

Yes, grout can be sealed. If you have a stone tile upon your floors or walls the grout should have been sealed at least twice when first installed and would subsequently be resealed when your stone tile is resealed.

If you have a ceramic or porcelain installation and wish to seal your grout, this can be done with either an aerosol spray or a liquid and is a relatively straightforward process.

It is worth noting that the grout should be cleaned and left to thoroughly dry prior to sealing. It is also advisable to try the sealant in an inconspicuous area as it may change the appearance of the grout, although this is rarely the case. The sealer may, if applied to the floor, need to be reapplied periodically due to the abrasion encountered over time by foot traffic. 

If I am grouting my bath or shower area do I still need silicone?

Yes, you would require silicone in the internal corners and around the bath or shower tray itself. It is important to leave a minimum of a 3mm gap between the bath/ shower tray and the tile above it. This is to allow for movement and prevent damaged or loose tiles in the future. The internal corners should have a gap of 6mm (as per British standards) and then silicone is applied within this gap. You should not grout the gap prior to siliconing as a rule (unless you need to use a clear product), in which case, enough silicone must be applied to provide a movement joint, not a thin application on top as this will not suffice. This should be considered a last resort and may need re-applying periodically.

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Will grout scratch my polished marble tiles?

Coarse-grained grout can scratch the surface of delicate surfaces such as polished marble. You will need to ensure you choose the appropriate super-fine grout for the purpose of grouting the marble. Always check suitability and then, to make absolutely sure, check on an off-cut first.

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Will the grout tarnish my metallic glazed ceramic tiles?

Quite possibly. You need to protect your tiles whilst grouting if they have a highly decorative finish, especially if a silver or gold metallic glaze is used. Some will come with a protective film and some will need to be protected with a low tack masking tape or similar. Again two rules apply: check the information that came with your tiles and the manufacturer's info/website. Also, test on an offcut of tile first.

Will the grout damage my metal tile trims?

Yes, if cement-based grout is left on the trim for a period of time it will erode and stain the tile trim leaving often irreparable damage. Some metal trims do have a protective film whilst damage can be avoided if the grout is wiped off immediately.

How do I remove the haze left after grouting?

This can be buffed off once dry with a soft cloth on the same day with relative ease. If left for longer than a day, or it is very hazy, then either a white emulsifying pad could be used, or it can be washed again and buffed (once dry) with a soft cloth.

What is the shelf life of a new bag of grout?

The shelf life of grout is generally 6-24 months depending on the manufacturer. Always check with your supplier if in doubt.

How long will an opened bag of grout keep?

An open bag of grout that is kept in a sealed airtight container, or has been taped closed will keep for a number of months. It is vital that it is kept airtight as otherwise it will draw moisture from the air and start to set (known as riced up). If there are small hard lumps within the opened bag of grout it is not advised to use it, instead, it is advisable to purchase a new bag.

Fugabella Grout & Silicone
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