DIYbanter - View Single Post

wrote in news:1106664607.408927.287970
@z14g2000cwz.googlegroups.com:

Due to slight wall shifting after adding a floor, I have cracks in the
grout near the wall borders. Is it better to mix new grout to fill the
gaps or add a silicone bead. (One of the cracks is in the tiled shower
floor and I'm worried about water getting under the tiles and causing
leaks below).

Grout (and concrete) is porous -- water is already getting through. Your
shower's waterproofing depends on a membrane underneath, not on anything
you do with grout or sealers.

A silicone bead is usually used at the boundary between the wall and the
floor of the shower, not for waterproofing, but for visual purposes.
Cracks almost always form at this boundary due to differential expansion
between the wall and the floor.

If the crack is in the middle of the shower floor, you are probably better
off by stripping out the old grout and regrouting. Silicone in the middle
of the shower floor isn't likely to stand up to the usage, and will almost
certainly start peeling away after a few months. However, you can always
try the silicone first and see if it holds up -- you may be lucky. Neither
action will have any effect on the waterproofing of your shower pan.