QUESTION

Freeze Thaw Resistant Grout - I have a patio that seems to be either flagstone or sandstone and the grout in some places is deteriorating. I want to fill in with new grout but I am not sure what I need to do. I live at 8000 feet in the mountains of Colorado so the patio is covered with snow about 6 months a year. Thank you for your help.

ANSWER

ANSWER - To replace the grout in a freeze thaw climatic area you should first cut out and remove the existing grout.  Make sure you first use a wet/dry vacuum to remove all the dust and debris, and then wash it down well and again use a wet/dry vacuum to remove all standing water.

For a freeze thaw application you should use a latex admix to your grout to make it stronger, more dense and more resistant to freeze thaw damage. Different manufacturers have different types of latex additives and different types of grout mixtures.  Visit our website at www.CTaSC.com and go to Expert Answers where you'll find Resources. Choose Installation Products where you can find a list of manufacturers with links to their websites.

After you replace the grout you should apply a sealer over the flagstone and grout to keep moisture from penetrating into them, which will further help keep it from being damaged by the freeze thaw climate. You should reapply the sealer every fall prior to winter freezing or more frequent.  For sealers go the cleaner and sealer section of the resources and links page. Good luck.