I have patio that's connected with brick from my house. Where the brick and the patio meet there is a crack along the entire perimeter. Its a fairly small no larger than a hairline crack. I'd like to seal that but i'm not sure what I would use to seal? I can attach photos for better understanding if need be. Thank you.

  • Please take the tour to learn what to do next. – isherwood Sep 16 '20 at 20:25
  • you need a picture to get this answered right – DMoore Feb 13 at 21:44

Urethane or silicone caulk are the usual, but there are others that remain flexible. Read some labels at your hardware store. Flexibility is crucial, so don't use latex. If you have a lot of seasonal movement (frost heave), caulk might not be a good idea anyway.

Either match color or go with clear. Use as small a bead as possible and avoid smearing it out onto either surface by cutting a fine, angled point on the tube and pressing firmly.

  • Thank you for the quick response. I'm very much an amateur so I have to ask. Is there a specific brand that is better than others? Also, I live in Michigan so yes I do deal with frost. If not caulk what other options are there? – Sal Sep 16 '20 at 19:48
  • Brand recommendations are off-topic here. Go with the more well-known ones and you should be fine. If I had other options for such a situation I'd have mentioned them. Since the crack is so small you're limited. Frankly, I wouldn't worry about it unless you have reason. – isherwood Sep 16 '20 at 20:25

Urethane caulk would be the go-to product, but hairline cracks are a bit of a problem.

If your crack was, say, 10mm wide and with temperature variations it widens or shrinks by, say 2mm, then that's only +/-20% width variation. Urethane caulk is elastic, so it'll stretch and squeeze and stay in.

However if you have a hairline crack, say 0.5mm wide, and temperature variations make it widen by only 1mm, then that's +200% width, and the caulk won't be able to stretch enough to stay attached to both sides of the gap.

If you want to seal it for cosmetic purposes, then just use caulk. But if you want it to be watertight to prevent water infiltration you really need to know what caused the crack, if it is going to widen in the future or not, etc.

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