Here is what it looks like on the porch, it has these groves that were created by the builder or whoever poured this enter image description here

The porch is like above and then here you can see the edge of the porch and the only stepping slab that is there and a gap between then that was filled with some weather resistant polyurethane caulk in front of the porch enter image description here

  • The grooves are crack control joints. They're there to try to help the concrete slab crack in a controlled way instead of having cracks run everywhere.
    – FreeMan
    Commented May 9, 2022 at 14:06

1 Answer 1


Do nothing! The adhesive you'll use between slab and tile will fill those gaps, and as long as it does, there won't be any weak points that may cause the tile to crack later, when walked upon.

  • Kind of what I was thinking but I was doubting the idea as these joints are like max 3/8" wide and 3/8" deep so where you have them you have 3/8" thinset mortar to compensate the joint and then add 1/4" more (when compressed) to support the tile so the "thinset" is not going to be exactly thin there. I am also considering self leveling cement since these will be 2'x2' tiles. Should I use 1 bag (covers 48sqft at 1/8") or two bags to get 1/4" coverage. I am inclined to go with 1/8" coverage that will level lower spots and fill the groves
    – MiniMe
    Commented May 9, 2022 at 14:20
  • Do not use self-leveler; mortar the tiles directly to your old (properly wire-brushed and/or acid-etched, and clean) concrete. IMO you will be increasing the chance of failure by trying to use leveler. Commented May 10, 2022 at 4:00

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