QUESTION

Grout for Exterior Tile - We would like to install some tile over a cement pad that is outside but we are wondering if there is something else other than grout that we can use. Can we use cement that has sealer in it? What about silicon? Do you have any other ideas?

ANSWER

ANSWER - First of all you need to be sure that the ceramic tile or stone tile that you want to use exterior is freeze thaw stable. The tile should not have more than a 3% absorption rate. You could use a silicon for grout and it would work well to make those joints water tight. It is not normally done. The silicon would have to have a shore hardness of 35 to be sure that women's high heals won't penetrate it and cause a safety issue. I'm not sure how easy it would be to install and to keep the silicone clean. It would be relatively expensive to use silicone.

You could also use an epoxy grout that is stain proof and is recommended for exterior use. At our website see the company Laticrete and Mapei under Installation Products listed under Expert Answers in the Resources column. Epoxy is not normally used exterior and it is a lot more expensive to buy and install. Normally it is recommended to use a polymer modified or latex modified cement grout, and then to seal with a sealer. Good Luck!