What Is Tile Grout?
Tile grout is a specially formulated material used to fill the joints between tiles after they have been fixed with adhesive. Although often overlooked, grout plays a vital role in the performance, durability and appearance of a tiled installation.
By filling the spaces between adjacent tiles, grout helps protect the edges of the tiles, reduces the risk of water and dirt penetrating beneath the surface, and provides a finished appearance that complements the overall design.
Modern grouts are available in a wide range of colours and formulations, allowing them to be matched to almost any tile while providing the durability required for both domestic and commercial installations.
Why Is Tile Grout Important?
Grout performs several important functions within a tiled installation. It helps to:
- Fill the joints between tiles.
- Protect tile edges from damage.
- Reduce the ingress of water and dirt.
- Support the tiled surface.
- Improve hygiene by sealing open joints.
- Enhance the finished appearance.
- Accommodate minor movement within the installation.
Without grout, tiled surfaces would be more susceptible to damage, contamination and premature failure.
Types of Tile Grout
Tile grouts are generally divided into two main categories.
Cement-Based Grouts (CG)
Supplied as a dry powder and mixed with water immediately before use. The most widely used type of grout, suitable for the majority of ceramic, porcelain and natural stone installations. Available in a broad range of colours with additives to improve flexibility, water repellence or stain resistance. Under EN 13888 these products are identified using the letters CG.
Reaction Resin Grouts (RG)
Commonly known as epoxy grouts, manufactured from resin-based components mixed immediately before use. Excellent resistance to water, chemicals, staining and abrasion. Commonly used in commercial kitchens, swimming pools, hospitals, food preparation areas, laboratories and industrial environments. Under EN 13888 these products are identified using the letters RG.
Understanding Grout Classifications
The European Standard EN 13888 classifies tile grouts according to their performance.
Cementitious Grouts
- CG1 — Normal cementitious grout.
- CG2 — Improved cementitious grout.
Additional performance characteristics include:
- W — Reduced water absorption.
- A — High abrasion resistance.
Reaction Resin Grouts
- RG — Reaction resin grout.
Because these products offer excellent resistance to chemicals, staining and moisture, additional classification letters are generally unnecessary.
Choosing the Correct Grout
The correct grout depends on several factors:
- The type of tile.
- Joint width.
- Wall or floor installation.
- Internal or external use.
- Wet or dry environment.
- Expected traffic.
- Exposure to chemicals.
- Colour preference.
- Manufacturer's recommendations.
No single grout is suitable for every application.
Grout Colours
Modern grouts are available in an extensive range of colours. Popular choices include white, ivory, beige, light grey, mid grey, charcoal, anthracite, black, brown and sand.
Matching the grout to the tile creates a seamless appearance, while contrasting colours emphasise the shape and layout of the tiles. The choice of grout colour can dramatically influence the finished appearance of a tiled surface.
Common Misunderstandings
"Grout is only decorative."
No. Although grout contributes significantly to the appearance of a tiled surface, it also performs important structural and protective functions.
"All grouts are the same."
No. Different grouts are formulated for different tile types, joint widths and installation conditions.
"White grout should always be used."
Not necessarily. Modern grouts are available in many colours, allowing installers to either blend joints into the tiles or make them a deliberate design feature.
"Grout makes a tiled installation waterproof."
No. Grout helps reduce water penetration, but it is not a substitute for proper waterproofing. Wet rooms, showers and other exposed areas should always be waterproofed using an appropriate tanking or waterproofing system before tiling.
Frequently Asked Questions
How long should grout cure before cleaning?
Initial cleaning is usually carried out shortly after application, but full curing times vary between products. Always follow the grout manufacturer's instructions.
Can old grout be replaced?
Yes. Existing grout can often be removed using suitable tools before new grout is applied.
Does grout need sealing?
Some cement-based grouts may benefit from sealing, particularly in areas exposed to staining. Many modern improved grouts already incorporate water-repellent technology. Reaction resin (epoxy) grouts generally do not require sealing.
Why does grout crack?
Cracking may result from movement within the substrate, incorrect installation, excessive joint width, unsuitable grout selection or inadequate curing conditions.
Conclusion
Tile grout is far more than a decorative finishing material. It forms an essential part of every tiled installation, protecting tile edges, filling joints and contributing to both the durability and appearance of the finished surface.
Selecting the correct grout requires consideration of the tile type, joint width, installation environment and expected performance. Whether using a traditional cementitious grout or a high-performance reaction resin grout, choosing the right product and installing it correctly helps ensure a long-lasting, attractive and reliable tiled finish.
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Browse Tiles →- Industry Standards
- EN 13888 — Grouts for tiles: Requirements, evaluation of conformity, classification and designation.
- EN 14411 — Ceramic tiles: Definitions, classification, characteristics and marking.
- Industry Organisations
- The Tile Association (UK).
- Technical References
- Manufacturer technical data sheets for cementitious and reaction resin grouts.
- Installation guidance published by leading grout manufacturers.