I need to make a water tight joint between the garage wall and the pavement:enter image description here enter image description here

I have cleaned out the debris from the gap and blasted it with water to remove all the loose little things.

Now, I have bought a sealant and want to apply it.

The problem that I'm seeing is that the floor of the gap is not even. Sometimes it's like 1.5 inches deep (where there were plants that I pulled out) and sometimes it's 1/2 inch deep:

enter image description here

How do I make it more even? Do I use a backer rod? If so, do I lay a continuous backer rod everywhere or only in the places where the gap is deep and leave the naked soil where it's shallow?

Can I apply the sealant on the soil directly (where it's shallow)?

Thanks kindly for you help. Jenia

1 Answer 1


You should stuff backer rod in where the depth exceeds 1/2", to conserve your sealant. That self-leveling sealant will flow/drop to the bottom of the opening rather than bridge the gap. You would get around 12' of fill from a single tube with a bead exactly 1/2" wide by 1/2" deep, much less than that if you don't fill it.

  • Okay. Just to make sure: where it's shallow, I don't put in a backer rod? I just apply to sealant on top of the soil? Jun 10, 2017 at 21:39
  • 1
    Yes, that should be fine. Tell me, is that wall discoloration due to rain water splashing from that tar/bitumen/asphalt surface at grade? Perhaps a couple of coats of quality exterior paint can help cover that. Jun 11, 2017 at 1:17
  • Okay, thanks!!. The discoloration, it's due to the water splashing. Why, is it bad for the wall-cement? Is it only aesthetics or is it actually damaging? Jun 11, 2017 at 1:19
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    Just wanted to confirm that it's not some nasty mold or mildew; if it's asphalt stains it is harmless, just aesthetics. Jun 11, 2017 at 1:25
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    Dries in 2 hours, full cure takes longer though. can you put a tarp over it or something? I think a little moisture won't be an issue but a flood might be. Jun 11, 2017 at 16:04

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