Holes and craters appearing in grouting.

[ceeceebee]

Hi, I live in South West France, near Montauban. About 6 years ago we laid tiles on existing sound tiling on a good concrete base, tiling a14 sq metre kitchen and smalll entrance lobby using standard 30 x30 tiles and Mapie grout. All seemed OK, except during the last 3 years a fair number of small holes (2 mm's say) have appeared in the grout, some have developed into small craters, quite regular in appearance. Only in the lobby area though. Have asked the tile and grout supplier (Pavan - a quite large supplier) and they don't have any idea. Could it be ants ?, we get some ants here which excavate their nests in the soil..... some other insect?.... Any ideas...anyone ??

 

[White Room]

Sometimes if you don't force the grout into the joints it could lead to slight small hollows under the finished surface and over a time with heavy use in that particular area appear.

They would have to be tough old insects but who knows on that department.

 

[Ajax123]

Pics??