Urethane grout to repair traditional grout?

Can urethane grout be used over traditional grout for this type of repair? I'd like to repair my glass block shower wall, but it looks to have traditional grout. I'm thinking of using urethane grout, since it would be easier to use and probably have a little flexibility, seal better, etc.

  4 answers
    • Richard Johnson Richard Johnson on Jun 15, 2018
      Unfortunately, as useful and interesting as this article is, it doesn't answer the question at all. The question was whether or not using urethane grout over regular sand grout will work for repairs, or is it not a good idea, and if not, why? Thanks for trying to help!

  • William William on Jun 14, 2018
    You will need to remove the old grout to be able to re grout. Yes you can use urethane grout. Can't put new grout over old.

    • Richard Johnson Richard Johnson on Jun 15, 2018
      This grout is the stuff holding the entire glass block wall together. If I actually remove all of the grout, I would need to rebuild the entire wall. Also, there is an article on this very web page telling how to repair the grout in a glass block wall, so it's obviously possible to repair without removing all of the grout. I'm just wondering if the urethane grout will adhere to the normal grout enough to seal it against water intrusion.

  • William William on Jun 15, 2018
    Glass block windows have no grout. They are installed just like bricks using Glass Block Mortar. Glass Block Mortar is a specially formulated product that is designed for glass block applications requiring white mortar joints. It can be used in both interior and exterior applications. What I meant is to remove the lines to a depth of about 1/4" by chipping or grinding without damaging the block. Then you can fill in with the urethane. Grout needs to grab the sides of tiles or in your case the blocks. Just putting it on the surface will just create a thin layer that will eventually fail. Just as repairing grout in tile you can't just fill gaps with new grout as it will not bond to old grout and will pop out. All grout need to be removed to replace with new.

  • Richard Johnson Richard Johnson on Jun 15, 2018
    Great! So, the urethane may not adhere to the old mortar, but will adhere to the blocks. Sounds good! I'll get some and give it a try. Thanks a lot for taking the time to fully explain it to me! I really appreciate it!