Patchy Grout

Patchy Grout

Photo 1 – The grout has patchy areas of light and dark.


The grout is unevenly finished in colour and may have a dirty appearance [Photo 1].


Technical reasons for patches in the grout

Morgan advises that there are numerous causes for patchy areas of light and dark within a grout –

  • Tile spacing lugs were left in the grout joints
  • There are inconsistent grout joint depths and gap widths
  • The tile adhesive has not been cleaned out of the tile joint before grouting
  • The tile or natural stone varies in density and porosity
  • Variable glaze on the tile edges caused the grout to cure at different rates and led to shading
  • The concrete substrate was not fully cured or had a high moisture content
  • Direct sunlight or too large an area grouted at one time before clean-up is initiated
  • Grout joints were excessively wiped during the initial cleaning process.


Recommended procedure for repairing patchy grout

Grout that has cured with a patchy appearance needs to be removed completely to the substrate and re-grouted.

Should you require any further information, please contact Morgan.

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