We had our bathrooms professionally installed, but the grout on the tile floors and some walls doesn't come to the top of the tile, there are empty ridges in all the grout lines that catch dust and dirt. I have never noticed this before, and in previous homes the grout always came to be level with the tile. I asked the contractor about this, but he said this is normal. Is there any professional standard for how deep the grout should be filled?

Thanks,

Amie