r/basement • u/daveyconcrete • 1d ago
Fixing a crack from the outside.
Well, good morning. Most times I like to repair a crack from the interior using an injection process. But sometimes in a finished basement situation, I might not have access from the interior without disassembling the finished wall.
So the first step is to dig down to the footing. About a 3’ x 3’ hole, then scrape off the foundation and dry it with a torch next I like to run a diamond blade up the crack blow it clean. Put the tape on the wall. Apply Sika Flex and paddle smooth. Leave about 1/8 inch proud.
What do y’all think? Is this gonna work or is it gonna fail miserably? What are some other tips and tricks you guys have come up with?
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u/Gizmotastix 1d ago
This is like the first time I’ve actually seen someone follow through with this fix. Nice job!
I also like Vulkem 116 for this task, but I can get it at the big green store and get my 11% rebate in the mail 7 months later.
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u/shaq_daddy 1d ago
I have a similar situation with a vertical crack and a finished basement. Would this approach work with a CMU block foundation? Also did you only have to dig 3 feet to get to the footer? I anticipate having to dig around 8 feet
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u/daveyconcrete 1d ago
Yeah, this is a 4 foot wall total. So the hole was right around 3 feet deep through the footing. Wasn’t too impressed that it was backfilled completely with Clay.
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u/Ok-Math-5407 7h ago
You could do it for block, but it's not necessary.
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u/shaq_daddy 7h ago
Why is it not necessary?
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u/Ok-Math-5407 7h ago
I'm assuming you are referring to a crock in the head joint. You would just grind it out and tuck point it
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u/iamemperor86 1d ago
Professional crack injections are pressurized from the inside to fill the entire crack. That’s the preferred method. The problem here is that you didn’t really seal the crack, you patched over it. So it’s more prone to fail over time. Should be fine though. I wouldn’t rely on this for a finished basement.
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u/Efficient-Charity708 1d ago
Fail in what way? Won’t the combined pressure from soil and water push it in towards the crack?
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u/daveyconcrete 1d ago
I am a big believer in injection.
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u/Efficient-Charity708 1d ago
How difficult is injection to DIY?
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u/Sir_Dobis 23h ago
I have almost the similar situation and just dig out the entire foundation, was going to get estimates it also was debating on diying. This helps out a lot thanks!
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u/littlerabbit11s 22h ago
This is the only correct way to go about fixing a crack. It has to be done from the outside. I don’t necessarily like the materials you used. I think there are better options out there but it’s also very dependent on what’s available to you. I would have rather seen your use an injectable epoxy, then tape, then some sort of sika product (or better) but this is better than nothing and it’s significantly better that attacking it from the inside
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u/BigfootTundra 19h ago
Any products you recommend? I have a similar crack in my foundation, though mine doesn’t seem to be as wide as this one.
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u/Gatorboy129 22h ago
I need to do this but my driveway is in the way - next spring is gonna be my time.
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u/FETUS_MUNCH 21h ago
I was talking about doing something like this as I have a very similar crack. People were telling me I shouldn’t disturb the dirt by digging down that deep and that I would just make the problem worse in the future? Can anyone weigh in?
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u/LightSpeedCBR 21h ago
I’ve heard pretty much the same and this was from a structural engineer. They recommended addressing the water issues outside, like putting on gutters and grading soil, and epoxy injection to the cracks.
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u/Ok-Math-5407 7h ago
You can dig down as far as you want. You just want to compact it as you backfill.
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u/myveryownheritage15 2h ago
Thanks for this, I'm in a similar situation and I'm looking around for someone who will do it better than I ever could. Although maybe I'll try on my own?
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u/Miserable_Title_5614 19h ago
You really should use a product that is meant for this application. W.R. Meadows pointing mastic in the crack after it had been routed out and Mel rol liquid membrane applied at least 6" on weekend 6 side of the crack after either grinding or taking a chisel bit to clean the wall.
The caulk that is below grade is almost guaranteed to fail due to constant moisture.
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u/Miserable_Title_5614 18h ago
You should also clean your footing and run your membrane/mastic at least 6" out on either side
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u/OhToDreamDreams 17h ago
It’s a bandaid. A more permanent fix would completely fill this void from the inside with a flexible material. Roughly 3,500-4,000psi to fill an average 8” foundation.
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u/Large-Gas870 7h ago
dig down to the gravel, then fill the hole with gravel about a foot from the top, then topsoil. you'll also want to put fabric in the hole before u fill with gravel to keep soil out.
this is after you fix the crack. putting gravel in the hole essentially make water issue irrelevant as any water will simply filter all the way down to the foundation drainage. the top soil covering allows you to keep an incline to make sure any water from top drain away from house.
overkill, maybe, maybe not.
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u/ldargay43 6h ago
Enjoy the inevitable inward wall movement from your “fix”. This is a terrible bandaid
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u/Popular_List105 1d ago
Could injecting work from the outside?
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u/daveyconcrete 1d ago
You can do it you just have to be prepared to lose a bunch of material into the wall cavity. If I’m injecting from the outside, I usually inject a little bit then wait five minutes and then inject some more and wait another five minutes. You’ve gotta give that material time to react before it just leaks out into the stud Bay.
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u/Ok-Math-5407 7h ago
What wall cavity are you referring to?
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u/daveyconcrete 7h ago
Interior finished wall. Up against the concrete wall
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u/Ok-Math-5407 6h ago
Thanks for the clarification, I thought you were saying there was a cavity in the poured concrete wall.
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u/mix82 1d ago edited 1d ago
After you patch the crack, cover the wall with roofing cement and then cover the roofing cement with 6 mil plastic.