Why does grout sometimes crack and how can it be repaired?

Question

This is a floor tile. The entire kitchen and entry hall was done. First they did a mud job. It was done 5 months ago. The spot leading from kitchen to hallway (2 tiles wide) is where it is cracking, by both tiles. That scares me and makes me think the problem is with the subfloor.

Answer 1

Some valid suggestions so far.

After installing multiple thousands of sq. ft. of tile, and hundreds of gallons of grout, those suggestions...all or some, might be the problem.

Flexing is a possible; as is improperly mixing the grout; or using the wrong grout, depending on the specific application. Vibrations in the subfloor or building IE: the extreme case an Earthquake zone, or less in an area adjacent to an AC room, or heavy traffic constantly moving over the grout. Water intrusion from under the tile.

I'm in a job site currently where tile and grout are subject to water seepage, and it could be a life long job? Not for me, but the issue exists. In my case, 11,000 sq. ft. of it, and the degrading of the grout happened because of the dergading of the mortar. Once set, the grout in many cases is FAST to the edges of the tile, whereas the mortar is crumbling.

Sanded grout works well for up to 1/2 inch lines, though I'd never use it that wide. Unsanded is usual for 1/2 inch or more.

REPAIR: This won't make you happy, but neither will just patching cracks. Best case scenario is to remove the grout in those areas; determine the WHY?, and RE-grout.

I'd be happy to do more detail in suggesting, if you gave examples of the situation.

Steven Wolf

Answer 2

Your tile floor may be layed over a sub floor. If so the sub floor is moving when walked on and in turn will move the tiles and crack your grout. Or the masonry board that should be in between the tile and subfloor was not glued down properly. If it is not on a sub floor then when the grout was done it most likely did not go all of the way inbetween the tiles or there was dirt and debris in the joints. You may also have some loose tiles which can cause the grout to crack. If it is a subfloor then the tile will need to be pulled up and installed properly ( hopefully this is not the problem). If it is the grout lines then you will have tho remove the grout and insure that the joints are free and clear of any dirt or debris and regrout. If it is a loose tile then pull it up and clean the area and relay it.

Answer 3

Grout can crack for any number of reasons. However, most often it is because of an improper mix with water when first applied. Another cause can be tiny shifts in the wall or floor on which it is applied. The grout does not allow any bending of any kind.

To repair, completely remove the grout and replace it. If it is in a problem area, a lot of cracked grout, you might try one of the epoxy grouts. They seem to hold better. Check with your local home improvement store or tile outlet. They should be able to advise you as to the steps you will need to take.

Good luck - anything to do with tile is always an adventure.

Answer 4

grout will crack when ther is not enough moisture. It is basically a mixture of sand and concrete and cloloring. Grout cracks for the same reason regular conmcrete and stone do. either it is dried out or it has shifted underneath it. Maybe when it was installed they did not ave the mix just right or the humidity is too high or low. You will just have to remove it and re grout your lines. A suggestions would be to seal it twice a year. This will help protect it and keep it from getting stained or use an acrylic based grout but you still want to seal those.

Answer 5

everyone seems to assume the cracking grout is in your floor tiles.
is it...? or is the cracking thats appearing in your grout ,in your wall tiles.
if the cracks in the grout are in your wall tiles, the problem could be a lot more serious than mixing your grout wrong.
if it is not to serious all you need to do is re-grout. but re-grout the whole area as you are very unlikely to get an exact colour match with the new grout.

Answer 6

if the groung iz cracking that meanz itz dry so try 2 water it