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A Short Word on Grout and Grouting

Black Porcelain Floor Tiles with Black Grout

This article will provide advice and shed light on a few of the finer points of grouting. Often seen as of lesser significance or importance compared with the other aspects of the project, grout is nevertheless a vital component of every properly completed tiling job.


We’ll discuss elsewhere on our site the more technical aspects of grout; suffice it to say there’s a European Standard (DIN EN 13888) which outlines the relevant classifications and requirements which manufacturers must observe. These relate to properties such as compressive and tensile strength, moisture absorption, suitability for extremes of temperature, and abrasion resistance, among others. For now, we'll concentrate on the most important issues to consider.

Modern Day Demands of Grout:

As tiles become larger, and rectified tiles become more prevalent, the challenge to fulfill every grouting application becomes ever tougher. Traditional sand and cement mixes cannot be considered suitable any more, and there is no “magic bullet” grout which will provide a solution for each and every circumstance.


In most cases where there’s failure with a given tiling project, it’s rarely the fault of the tile itself. And while substrate movement is the number one problem, in many instances a poorly performing grout joint can be the culprit.


Thankfully, the current generation of joint grouts are able to deal with these demands, giving extra choice to consumers, and improved support to tile fitters. They provide exact solutions to specific applications.


Water Resistant GroutOn top of this, grout has to be aesthetically pleasing, while at the same time being functional. There is now available a wide array of colours, grades, and finishes from most manufacturers. Finally, beyond industry standards, many grouts now incorporate additional ingredients, such as those that deter mould and other microbiological organisms, and others that are repellent to water and dirt.


Types of Grout:

Cement based grouts are produced from Portland cement, pigments, and other additives. These are the most common types used in residential situations. In general, un-sanded grout is used for walls and narrow joints, whereas cement with fine grade sand included in the mix will be mostly used on floors and where there are wide joints.


The purpose of the sand is to increase the bulkiness of the grout in a wide joint. It offers something for the cement to bind to as it cures. In its absence, it’s possible that the cement, as it cures and loses moisture, will shrink too much and end up cracking, or slumping into the joint itself. It’s possible that un-sanded grout does actually have the very finest of sand included. There are usually agents added to the ingredients which help the grout retain its moisture as it cures.


Ideally, un-sanded grout will be used in situations where the tile and adhesive behind it have dried completely. If excess moisture is present in these materials, it can be absorbed by the grout and lead to a defective finish. Sanded grout can be applied in areas where there may be some residual dampness from the installation of the tiles. It’s usually not recommended to grout within 24 hours of fixing the tiles.


Where sanded grout is used in the joints of delicate materials, such as polished marble, it’s advisable to test it in a small inconspicuous area first, as the abrasive nature of sand may lead to scratching of the surface as it’s applied.


Laying Grout onto Floor Tiles


Epoxy grouts contain no cement, rather a resin combined with a filler and a hardening agent. It too can be produced in sanded and un-sanded varieties. It has exceptionally high water-resistant properties. There’s generally less chance of there being any cracking when this grout is used.


Epoxy grout also boasts an extremely high resistance to staining. It is often used in commercial kitchens or areas of high stress. However, it is considerably more expensive than regular cement based grout, and is far more difficult and time consuming to use. It can also leave a “plastic” looking finish to the joints, which is often not desirable. Having said that, epoxy grout does provide a more consistent and even colour in contrast to cement based grouts, which can sometimes appear patchy due to some finer pigments being wiped away during the final clean at installation time.


Flexible grouts (cement based) allow for more movement in the substrate, and more scope for thermal expansion. For the almost negligible price difference, we recommend using flexible grout in all situations regardless of necessity. This will provide an extra layer of protection against these problems, as well as peace of mind.

How Wide Should the Grout Joint Be?

The answer to this question is: it depends! As with many things in the tiling industry, there are no specific regulations, which becomes clear when you consider all the different factors that need to be taken into account. In a perfect world, the joint will be of uniform width throughout the entire project. So it should just be a case of choosing a width that suits the tile and is aesthetically pleasing, and committing to that.



  • Within a batch of tiles there’s a slight variation in sizes, within a certain tolerance. As an example, a 20 square metre floor of 60 x 60 glazed porcelain tiles may contain a range of tiles whose sizes could see the length or width of the largest one be up to 0.5 mm greater in length or width than the smallest (this is acceptable within the industry). Additionally, any individual tile may not be perfectly square, for two possible reasons - its length and width are not the same, so you have a rectangle, or the tile has a slight taper, and the corners are subsequently not perfect 90 degree angles.
In such a case, a larger grout joint, of perhaps 5 to 8mm, will need to be incorporated into the project to allow for the resultant variations in tile size. The installer should be aware of this, and one of the skills involved is to select tiles in such an order that will minimise disruption to an even grout line. The tighter the joint in this situation, the more obvious the discrepancies between tiles will be.
  • Rustic style or hand-made tiles often possess “wavy” sides, which may not match up with each other from tile to tile. A particularly large grout joint is required in this situation.
  • Rectified tiles, on the other hand, have much greater consistency in size and squareness. Often a tight joint of 1.5mm is achievable here. Note that any less than this could see the tiling project fail, as there will not be enough “critical mass” of grout for it to maintain its integrity, as well as allowing for local tile expansion considerations.
  • A function of the grout joint is to allow for changes of levels across a floor, or indeed a wall. Where the surface of the substrate is not perfectly flat, it follows that there will exist small humps and hollows which the grout lines must follow. As the tiles cannot stretch or shrink to fit perfectly over such shapes, it also follows that the width of the grout joint will open up (over a bump), or close (in a hollow) in order to accommodate the difference.
  • Where the tiles themselves are laid at slightly different heights, the grout can be “sloped” slightly, forming a small ramp from one to the other. This will also result in the appearance of a wider joint.

Which Colour Is Best?

It’s generally underestimated how crucial the grout colour is to the finished appearance of a job. We present the following image of the same tile, grouted in different colours, and allow you to make up your mind:


Mosaic Tiling with Grout


At Tile Devil, we recommend a darker grout for all floor tiles that will be installed downstairs (or at ground level) in a home. This is where shoes bring in everyday dirt and dust from the outdoors. The floor is subsequently mopped, and even with the best grout sealer, it’s inevitable that the grout will discolour sooner rather than later.


In upstairs areas, in particular upstairs bathrooms, we recommend using a colour that most closely matches the tile (unless a specific look is sought, such as a white tile with black grout). The traffic in these areas is often not shod, and consequently a lot cleaner, thus the grout is far easier to maintain.

To Wrap Up:

Grout is one of the most crucial elements of any tiling job. It’s important to select the correct type and colour for your job, as it will greatly influence the appearance of the completed project.


If you're unsure which grout to use for your job or the quantities required, just send us an email with the tiles you're interested in, the floor sizes, wall sizes, room types, and any specific requirement you have. We'll get back to you with the answers you need.

Photos Provided By Botament Systems.

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