Below you'll find a selection of categories and topics with a series of answers from commonly asked questions. Mark (our director and founder) has taken the time to compile an almost exhaustive list to help inform you and answer any queries you may have about tiling and tiling products.
Please click one of the titles below to find out more!
Grout & Epoxy
Is Grout Waterproof?
It depends on the grout used. Broadly speaking the answer would be no, as the most common grouts are cement-based (cementitious), being porous in nature (this includes allowing the passage of water through them), it can stain and change colour when wet but does not break down when exposed to water. When using cementitious grout, it is wise to waterproof your walls by using a waterproof solution and tape called tanking.
Epoxy grout, however, is totally impervious to water and therefore waterproof. It is also chemically resistant, resistant to stains and retains the same shade of colour whether wet or dry due to the fact it’s impermeable. It is the perfect choice for many situations including food prep areas and operating theatres, as well as domestic situations.
Epoxy should be applied by a professional unless the user has experience or is very confident in its use!
If cementitious grout is not waterproof, why is it suitable for swimming pools?
Cement-based grouts are water resistant not waterproof. This means it will not break down when subjected to immersion and will remain unaffected by constant submersion.
Why doesn’t the swimming pool leak if the grout is not waterproof?
The structure of the swimming pool must hold water in its own right, therefore it is tanked (waterproofed) prior to tiling and tested to ensure that, once filled, the water level does not drop beyond the expected allowance. The tiling is applied as a decorative veneer and is not a factor in making the pool waterproof.
Isn’t water-resistant and waterproof the same?
No, water-resistant and waterproof are not the same and this is where a great deal of confusion arises. In simple terms waterproof grout, such as epoxy, repels water and is impervious to it meaning it is waterproof. Whereas a cement-based grout, although will not be worn down or damaged by constant wetting, does not repel water and instead absorbs it; therefore it is water-resistant but not waterproof.
What types of grout are there?
Grout generally falls into two camps, either cement-based or epoxy (as described above). Most grouts nowadays are flexible to allow for movement within the subfloor or walls but remain structurally strong enough to fill grout joints from 2mm to 20mm - and are also antibacterial! However, there are grouts that are designed specifically for narrow or wide grout joints or specific tile materials - for this reason, you should check the packaging.
Epoxy will do all of the above and has the added characteristics of being waterproof, chemical resistant and sterile, but does cost significantly more. It is more difficult to apply, requires mixing of two chemical components to create the epoxy and should be applied by a professional unless the user has experience or is very confident in its use.
For more information about antibacterial grouts, check out our blog here.
How many colours of grout are there?
Grout manufacturers produce an array of colours that offer a great choice of aesthetic options. After all, grout is a decorative addition to the tiling and the colour palette can act to blend or contrast with the tile choice. We at MTM Tile Showroom stock 50 colours within the showroom that are all eco-friendly, so the options are plentiful.
Can I get a silicone to match my grout colour choice?
Most manufacturers of grout also manufacture silicone that match the grout colours that they produce. However, some manufacturers produce a limited selection of silicones that accompany their most popular grout colours, so it is best to check first. MTM Tile Showroom stock all 50 colours of silicone to match our full range of grout colours.
What if there is no matching colour silicone to my grout choice?
If you cannot obtain a matching silicone and do not wish to use a colour that would stand out, such as perhaps a stark white, you have two options:
Is the silicone an exact match to the grout colour?
As the silicone is a different material to the grout, the appearance will be slightly different and will have a sheen/gloss finish as opposed to a matt finish. The colours will be very similar but may not appear as an exact match for this reason.
What are the benefits of epoxy grout?
Epoxy grout has several benefits over and above the cementitious grouts, namely: increased strength and abrasion resistance, chemical resistance, and is waterproof. These traits make it ideal for sterile areas as it does not absorb liquids or allow bacteria growth and has a high degree of flexibility. As it is inert, it does not give off or leach any chemicals that could prove harmful to the environment or the end-user/customer.
Can epoxy grout cause an allergic reaction?
Our epoxy grout is water-based and is therefore hypoallergenic (unlikely to cause an allergic reaction) unlike other epoxy grouts that can cause problems of an allergic nature, especially for people with sensitive skin. A little research into the formulation of your chosen epoxy grout would be beneficial prior to purchase.
Is Epoxy grout harder to work with?
Epoxy has two components that are mixed to form a resin. This grout should be applied by a professional unless the user has experience or is very confident in its use. It is harder to use and more time consuming to apply than a cementitious grout, but a professional tiler will be able to apply it and the long term benefits will certainly outweigh the short term increased costs and time involved.
How much extra does epoxy grout cost?
Epoxy grout typically costs an approximate £15.00 per m2 more than cement-based grout. This includes the increased cost of the product itself, sponges/ emulsifying pads and the extra labour that is required to achieve the perfect finish.
For a more in-depth explanation, please see below.
All prices are approximated. Your pricing will vary depending on the size of the tile, size of the room and choice of grouts (cementitious or epoxy, colour and supplier).
On average, a cement-based grout costs £1.60 per m2, whereas an epoxy counterpart would cost £11 - £17 per m2 (including required labour & tools).
A bathroom of 18m2 with wall tiles 300mm x 600mm, would cost approximately £28 for the cementitious grout and materials. The same room and tiles using an epoxy would cost between £135 - £180 (including materials) - this does not include the extra labour (£50 - £90) and additional tools required (£20 - £30).
Is grout antibacterial?
Always check the label!
Many grouts are antibacterial and have a resistance to the growth of bacteria and mould; however, some antibacterial products contain chemicals that, while regulated in other industries (e.g farming), are not in the construction industry, and are considered potential carcinogens due to their ability for particles to become airborne.
Over time, non-antibacterial cement-based grout will become less effective as the pH value of the grout lowers due to salinification and as the lower pH values are less resistant to bacteria growth. For this reason, the manufacturers use either a pesticide, fungicide or a natural product to ensure the antibacterial properties remain active throughout the life of the grout.
We choose to use Kerakoll grouts (other makes are available) due to their eco-friendly, safe-to-use nature and ensure the end-users safety. Kerakoll creates their own products to help realise their values, innovating in many areas to keep workers and occupants safe during and after construction with alternative formulas and compounds in their products.
If you wish to learn more about antibacterial grout or how Kerakoll has achieved this please read our blog here.
Is there anything used in grout that can cause me harm?
Some products contain components that are considered carcinogenic due to their capacity to become airborne and can be harmful to humans, as mentioned above.
We use Kerakoll products which protect the end-user wherever possible by using hypoallergenic components in their products.
For more information about our Kerakoll products please click here.
Is grout mould resistant?
Generally, most modern-day grouts are mould resistant (please check the packaging) and the manufacturers achieve this resistance in different ways. Some use pesticides or fungicides which can be harmful to humans and some use natural methods such as lime to make the grout permanently resistant to mould and bacteria.
Please see our blog on antibacterial grout for more information here.
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.
Is grout flexible?
Most modern-day grouts are flexible and many manufacturers also produce a flexible liquid additive to further enhance the flexibility and abrasion resistance of the grout. Although the grouts are flexible and will cope with underfloor heating and slight movement, they will not cope with unstable backgrounds where the movement is more than slight. These backgrounds need to be addressed prior to the tiles being laid.
What grout is used in sterile environments such as food prep areas and operating theatres?
The grout that would be used in these situations is epoxy because of its resistance to chemicals and the fact that it is inert and impermeable.
Epoxy should be applied by a professional unless the user has experience or is very confident in its use!
How do I restore my grout?
You can restore your grout in a number of ways. Some are easier to apply than others and some have a longer life than others. You can use an appropriate cleaner if your grout is in good condition, or if your grout is a little soiled or has a slight build-up of mould it can be removed by an appropriate mould spray or cleaner.
If the grout is in good condition but appears dull, there are products that can be applied to the grout to re-colour and seal the grout. These can last up to 15 years and are generally epoxy-based solutions. You can even change the colour from one colour to another, for example, light to dark and vice versa, using the aforementioned epoxy liquids.
If the grout is in bad repair the most likely course of action would be to carefully remove the existing grout and regrout the area.
Can I change my grout colour?
Yes, there are several products that are manufactured to restore and recolour grout joints. These generally work by using a pretreat solution which is normally acid-based to clean and etch the existing grout joint. It is then followed by applying an epoxy coloured solution, this can be beneficial if you wish to change from light to dark or vice versa. It can however leave a sheen on the grout joint and change the appearance, therefore it is best to try it first somewhere inconspicuous.
How do I clean my grout?
The best way to clean your grout is with a pH neutral cleaner which should be available from your local tile supplier. It is not advisable to use harsh bleach-based cleaners or washing up liquid; nor is it advisable to use acidic or alkaline products regularly. There are specific cleaners should your grout need a deep clean prior to everyday cleaning. Again these are available from your local tile showroom.
Is there anything I should avoid using when cleaning my grout?
We strongly do NOT recommend the use of harsh bleach-based cleaners or washing up liquid (due to high salt content); nor is it advisable to use acidic or alkaline products regularly. These can all break your grout down over time and will certainly break down any sealer applied to your grout. The best cleaner is a pH neutral cleaner which should be readily available from your local tile showroom.
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.
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.
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 aid 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.
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, 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.
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.
Are grouts UV resistant?
UV light can bleach colours depending on the polymers and pigments used. Some grouts have very good UV protection and are ideal candidates for external areas or areas subject to strong UV light.
Check with your supplier if this is an important requirement.
Our range of grouts do have excellent UV resistance as do other ranges that are available.
Are there any grouts that don't use harmful chemicals?
There are grouts that use natural products such as NHL lime to ensure antibacterial properties remain active within the grout throughout its natural life, as opposed to other manufactured chemicals.
Please see our blog on antibacterial grout for more information here.
Why has my grout dried patchy?
Grout containing ordinary portland cement to a large enough extent (cementitious grouts) can, and often do, contain salts which if overly wetted can come to the surface causing efflorescence (a white/milky effect). These grouts are particularly prone to Portlandite - the unsightly salt and lime efflorescence caused by the inclusion of Portland cement. There are some grouts that don't contain this element and therefore do not dry patchy. As always, check with your supplier. Our ranges don't contain Portland cement and therefore do not dry patchy. There may be similar products available from other manufacturers.
How do I remove efflorescence from my grout?
Efflorescence may be removed by simply washing the surface of the grout and again a few days later, with clean water. Or preferably using a diluted acidic solution (i.e using an acid-based cleaner and following the manufacturer's advice).
The third way, if the two aforementioned remedies fail, is to use an epoxy-based grout colourant. This will recolour the grout to a uniform appearance, although it may come away from the surface over time due to wear and tear and will have a slight sheen in appearance. Therefore it may not suit all applications and an inconspicuous area should be tested first to check the finish is acceptable.
If these remedial actions don't work, then unfortunately the only course of action left to remedy the situation is to re-grout the affected area.
Are ready mixed grouts better than powdered grouts?
Not often, as ready mixed grouts were designed for the DIY market and for convenience. The problem with ready mixed grouts is that the consistency is often quite wet leading to small pin holes once the grout dries. It also has a limited range of colours and tends not to be as economical as powdered grout, as you are essentially paying for the convenience. It is also harder to clean off than powdered grout in most cases. Where it is possible to use powdered grout it will open up more choices in terms of colour and generally have greater strength, along with other characteristics such as a higher abrasion tolerance. Also ready mixed grouts tend to be in decline now and are rarely, if ever, used on floors.
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).
Are there any grouts that don't dry patchy?
There are grouts that don't dry patchy. Epoxy and grouts with no Portland cement, such as Kerakoll Fugabella Color, do not dry patchy.
Why would I use an admixture with my grout?
Grout & Epoxy contd.
Why has my grout cracked?
Movement within the background or substrate is the most common reason for grout cracking, although other more uncommon reasons include:
How can I fix cracked grout?
First establish why the grout is cracking, i.e. movement - Are there loose tiles? Is the substrate or background moving? Is the grout too weak?
In the case of loose tiles, check this is not due to the background either moving or proving incompatible with the type of adhesive used. Equally check the correct adhesive has been used and that the bed was not made up of blobs of adhesive (another cause of cracked grout and loose tiles) as opposed to a solid bed. If it is the background, limit the movement and re-stick the tiles before grouting. If it is just the tile, re-stick this and re-grout.
If the grout is too weak, remove and replace.
Where there is no possibility, or you are unwilling to remove tiles, you could rake the grout out and replace it with epoxy. This will generally stop the cracking of the grout as it is very strong and flexible.
BE WARNED: IF YOU DO THIS THE CRACKS MAY APPEAR ELSEWHERE! - Cracks will appear at the weakest point which would not usually be the epoxy grout.
Why are there small (pinholes) in my grout?
This occurs when the grout is mixed too wet. As it dries small pinholes can be seen in the joints, and you will need to go over the joints again to fill the holes.
It is also common in ready mixed grout, and applying more grout over the pinholes will generally work. A powdered grout is a better option from the start rather than a ready mixed grout.
What are the most popular grout colours?
Currently the most popular colours are white, cream and shades of grey from very pale through to anthracite tones. These are in keeping with current tiling trends.
It does of course depend on your requirements, as blue is one of the biggest sellers in epoxy due to its use as both an adhesive and grout for blue mosaic tiles in swimming pools.
There are of course a wide variety of grout colours, so choose the one that’s right for you!
What colour grout is recommended for encaustic tiles and why?
Encaustic tiles are made from different coloured cements that form a pattern within the tile, which also gives the tile very porous and delicate properties. They require many coats of sealer and an ongoing maintenance program to ensure longevity and a pleasing aesthetic.
The manufacturers will often only recommend white grout as this does not carry the risk of staining the tiles due to its lack of pigments unlike the coloured grouts.
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.
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 manufacturers 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 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 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?
Do not wash off gout in circular motions! The best way to wash grout off is to use a damp sponge (not overly wet and wring it out before using) and once the grout is starting to harden slightly, lightly (so as not to pull the grout out of the joint) drag the sponge across the tile and joint over a length of no more than 50cm. Do not use this side of the sponge again, instead use the other faces of the sponge - use each face once only - then rinse. Repeat if you need to remove excess grout or marks in the area you have just washed ensuring to use a clean face of the sponge.
Using the method above, continue until all the tiles are clean. Adopting this method will pay dividends when it comes to the final stage of buffing off any grout dust as it dries. In contrast to washing off in a circular motion, you will find very little residue to dust off. You can repeat the washing off process above if required once dry for textured tiles or coloured grouts, although if the procedures above are followed this is rarely required.
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.
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.
Does epoxy grout cause an allergic reaction in users?
Epoxy grout can cause an irritation and allergic reaction in people; however, there is now a water based epoxy resin that is hypoallergenic produced by Kerakoll although there may be other manufacturers.
How do I use glitter grout and what is it?
Glitter grout is essentially a clear epoxy grout that is thoroughly mixed with a sachet of coloured glitter, that once set, the glitter can be seen in the clear epoxy. When parts A and B of the epoxy are mixed, the glitter sachet can be added and well mixed at the desired ratio. Glitter sachets come in a variety of colours (mainly metallic) so you can achieve almost any look you desire.
How long should I wait before using my shower after grouting?
This will depend greatly on the grout used and environmental factors as well as the manufacturer's instructions, so check first. Typically this can be from 3 to 14 days.
How long before I can fill my swimming pool after grouting?
Depending on the type of grout used it is normally around 3 weeks (21 days). Check the manufacturer's instructions.
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.
Is there any way of changing the grout colour once it has been grouted?
Yes, you can change your grout colour without removing it! There are products that can be used to re-colour existing grout which come in a variety of colours. They generally consist of a pre-treat acidic cleaner and an epoxy formula colourant (due to the acidic content in the pre-treat cleaner these products are not suitable for natural stone). There are other products which are used directly onto the grout joint without the pretreat solution, but these are best used on new and clean grout joints.
How do you achieve a smooth and consistent grout joint?
You would normally achieve this by gently smoothing the joint with a damp sponge (as in the answer to washing off grout). You can also use a round smoothing tool and run this along the joints before washing off to give a consistently uniform grout joint.
Can the grout cause an allergic reaction or skin problem?
Both cementitious and epoxy grouts can cause skin irritations such as dermatitis and provoke an allergic reaction, however, there are now hypoallergenic epoxy grouts available on the market.
Please be aware that cement-based grouts can also cause cement burns and damage to the eye if contact is made.
It is advisable to wear gloves and protective safety glasses when applying the grout, and when mixing, also wear a face mask as particles of the grout’s components can become airborne and are not safe to inhale.
Can I use grout as an adhesive?
Yes, you can use epoxy grout as an adhesive, aside from its bond strength and resistance to many chemicals, it is an ideal choice for coloured glass mosaics. As the colour of the adhesive matches the colour of the grout, it is ideal for glass mosaics where the adhesive may be visible from the front due to the transparency of the glass; i.e a blue glass mosaic with blue adhesive and grout will give a truly uniform finish.