TN 06.23 Common Issues With Grouting TN 06.23 Common Issues With Grouting

TN 06.23 Common Issues With Grouting

Kirsty W Kirsty W


Cementitious based grouts conforming to BS EN 13888 are available in a wide variety of colours.

Essentially cementitious based grouts consist of a cement binder, fillers, polymers, pigments and other additives which when combined give the grout its colour.

Plastic colour swatches give a good approximation of the grout appearance. Swatches should be placed in between the tiles selected and viewed under similar lighting conditions under which the tiles will be installed.

All BAL products are manufactured to a Quality Assurance standard conforming to BS EN ISO 9001 and are tested for colour consistency before leaving the factory compared with a laboratory standard grout.

Whilst the EN standard assess the physical and mechanical characteristics and performance of the grout, the grouts appearance and colour perception can be influenced by how the grout is mixed and applied to the tile joints, the colour and type of tile installed as well as on site conditions.

The way in which the grout is mixed and applied can have a direct influence on the degree of hydration of the cement binder and therefore influence the final grout colour shade. It is, therefore, equally important to ensure that the same amount of care and attention is taken when applying any grout as it is for the application of the tile adhesive.

BS 5385: Part 1: 2018 advises the following in clause 4.2.2 Lighting on site:
“Lighting on site should be of similar type, direction and intensity as envisaged for the completed installation.

NOTE If this condition is not met, then the appearance of the finished wall tiling might be different from that originally intended; serious consequences might then result, including the necessity for complete re-tiling”.

Common grout issues encountered on a regular basis include:
1. Colour variation between Grout Joints (Application)
2. Colour variation between Grout Joints (Visual/ optical illusion).
3. Whitish salt stain deposits on the surface of cementitious grouts or tiles (Efflorescence)
4. Cracking/ debonding of grout joints

It is, therefore, equally important to ensure that the same amount of care and attention is taken over applying any grout as it is for the application of the tile adhesive.



Variation in water content between mixes of grout. Be consistent with the amount of water (or liquid admixture e.g. BAL ADMIX GT1) used from mix to mix.
Changes in temperature and humidity (Atmospheric Moisture) and grout drying rates. Ensure where practicable that the temperature is maintained as close to room temperature as possible i.e. approximately 20°C, particularly during the colder months of the year. Improved drying out.
Delayed cleaning up of the grout. Be consistent with clean up of grout. Ensure grout achieves an initial set. Avoid over washing and use a ‘damp’ sponge.
Adhesive not fully drying out prior to grouting – Migration of moisture through tile joints. Allow the tile adhesive to fully dry out before grouting commences as per the manufacturer’s recommendations.
Porosity of tiles may affect hydration i.e. by removing moisture from the grout. Try to use tiles with a similar absorbency on each visual plane. Use of polymer modified grouts will help to reduce the problem.
Over washing grout joints during cleaning off process. Do not use excessive water during the grout cleaning-off process.




Lighting conditions on site i.e. light vs. shade

BS 5385-1: 2018 7.1.10 Lighting;

“The type, direction and intensity of lighting at the time of tile fixing should not be appreciably different from the ultimate permanent lighting.

NOTE Within the tolerance determined for the overall plane, there could be minute differences of plane between adjacent tiles that can be rendered visually insignificant in the ambient lighting by adjustments of the tiles during fixing. If the finished tiling is subsequently exposed to lighting from a different source, its appearance might be affected, and no adjustments can then be made to the tiles to meet the changed circumstances”.

Visual impact of the field tiles on the colour of the grout in between tile joints.


• Consider the colour of the tiles, including any shade variations apparent within the field tile compared with the colour of the grout selected. Check the colour of the grout with the field tiles, ideally under the final lighting conditions.

• Variegated tiles should be mixed by selecting from several boxes as fixing proceeds.

• The distance at which the joints are viewed can alter perception. Look at the tiles and grout at approximately 1m away as a final check.

• If the grout is recessed in between the tile joints, the grout will be perceived as being ‘darker’ than the tile.





Damp rising through the sub-base or a high-water table Ensure all direct to earth sub-floors have a suitable DPM before tiling.
Tiling in poor weather or cold temperatures/ On site conditions


• Delay work in poor weather conditions and increase the site temperatures, where practicable.

• Protect work outside from inclement weather.

• Do not work below 5°C.


Excessive water being used during the cleaning off process Do not use excessive water during the cleaning off process. Always use a ‘damp’ sponge. Apply as per the grout manufacturer’s recommendations.
Grouting in areas with high humidity Delay until conditions improve or de-humidify room in very damp conditions.
Mixing the grout too wet before application Be consistent with mixing of the grout and always mix as per the grout manufacturer’s recommendations.
Grouting too early i.e. whilst the tile adhesive is still wet. Allow the tile adhesive to dry out sufficiently before grouting commences as per the manufacturer’s recommendations.





Movement stresses;

- Vertical deflection

- Drying shrinkage

- Thermal expansion/ contraction

- Moisture expansion


Use adequate movement joints in the installation;

Ensure substrate is rigid and free from vertical deflection movement.

Allow newly laid construction backgrounds to cure and dry out adequately before tiling commences (See BS 5385: Parts 1-5)

Floor tiles not fully restrained i.e. loose All tile should be fully fixed to their adhesive beds. Remove loose tiles, re-fix tiles and re-grout


Shrinkage within the grout due to rapid moisture loss Allow grout to dry at temperatures not exceeding 25°C. Check porosity of the tiles
Grout mixed too wet before application Mix the grout to the correct powder to water ratio.


5. Summary Table – Causes of Shade Variations, Efflorescence and Cracking of Grout Joints.


Darker Colour to the Grout Lighter Colour to the Grout Efflorescence Cracking of Joints

Porous bodied tiles

(Increased water absorption)

Porcelain tiles

(V. low porosity)

Porcelain Tiles Very Porous tiles (Rapid water loss)
Low humidity High Humidity High Humidity -
Grout mixed too dry Grout mixed too wet Grout mixed too wet

Grout mixed too wet


Delayed cleaning off the grout Over washing joints too early Over washing joints too early Over washing joints too early (Shrinkage)
Field tile lighter than tile grout Field tile darker than tile grout - -
Deeper Joints Shallow Joints Deeper Joints Shallow Joints i.e. capping off
Higher temperatures Colder temperatures Colder temperatures Higher temperatures
- - - Movement


For free expert guidance on the use of BAL products, or any aspect of ceramic tiling with BAL products, contact the BAL TECHNICAL ADVISORY SERVICE on 01782 591120.

BAL products are supplied with a 25-year product guarantee. For further details and/or copies please contact the Company’s marketing department.

The customer must verify the suitability of any information, opinion, recommendation or advice (“information”) provided by the Company for the particular application for which any goods are intended to be used and the Company accepts no liability (whether in contract, tort or otherwise) whatsoever for any loss, damage or expense arising from the misuse of any information it supplies, nor for the use of any information in or for applications which are unsuitable or inappropriate. Building Adhesives Ltd operates a continuous research and development programme and reserves the right to alter or to update information from time to time.

“Note: Any advice, opinion or information is given to assist the use of the Company’s products on the basis that the user will ensure its suitability for the application intended. In particular the Company cannot accept liability for loss or damage which may arise from incorrect use of its products or from poor workmanship. The Company operates a continuous research and development programme and reserves the right to update information without notice.”

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