My house is 18yrs old and I have a vertical hairline crack in the basement. It seeps in water when it is pouring outside during storms otherwise it is ok. I want to repair this crack and was researching online. I am confused which option is best:

  1. There is a kit that put the plugs ever six or so inches over the crack and then you inject polyurethane foam. (like this one https://www.radonseal.com/product/301.html). This is more tedious process, and cost little bit more.
  2. Second option to use a caulking gun with a product like this: https://www.homedepot.com/p/Sikaflex-10-1-oz-Crack-Flex-Concrete-Sealant-7116110/300934565#overlay It is fast and cheap.

I am not sure which option is best and give good result without spending too much of money. Please help. Thank you.

  • 2
    Second option is only for floors, not walls. Usually the best long lasting(life time) repairs should be done from the outside. Requires digging, but repair itself usually inexpensive. Could also make sure water does not flow to wall by proper grading of ground and rain gutters.
    – crip659
    Jun 22, 2021 at 15:51
  • Yep, repairing such things from the inside is a game of whack-a-mole. If there's water pressure it'll find a way in. Fix grade outside, deal with roof runoff, and, if needed, excavate and repair.
    – isherwood
    Jun 22, 2021 at 15:56
  • 1
    So, in case it's not apparent, you've asked an XY question about your proposed solutions instead of the actual problem. You might revise to open up for better answers. Photos would be great.
    – isherwood
    Jun 22, 2021 at 15:57
  • 1
    you say hairline crack but water is coming through it, so I wonder how much hydrostatic pressure you're getting from the outside of the wall. The best solution is to fix this from outside. How far up the wall is the crack located? (near the floor or higher?) Do you have poured walls or block?
    – Phaelax z
    Jun 22, 2021 at 17:15
  • 1
    sounds like you need to clean/update your gutters; i know it's un-intuitive, but it makes a huge difference. You need to worry about ice much more than rain, and stopping the rain from getting inside won't stop ice from cleaving apart your foundation walls just behind your patch. Fix the outside and repaint the inside.
    – dandavis
    Jun 22, 2021 at 19:34

3 Answers 3


Dave since you have a sump the high ground water is controlled by that and usually foundation drains that feed the sump.

The crack is allowing water that is from the surface to enter.

As others suggest getting the water away from the foundation is your best chance of anything being successful.

I have never had problems with ice heave on walls but where I lived it only got to -20f.

Making sure the gutters are directing the water away as we have mentioned should be first priority, since the crack is close to the surface you may be able to seal the top few feet with minimal digging from outside if the problem continues.

When it comes to inside patches I have rarely had a complete dry wall after patching it seams the water finds other other ways in unless the water is eliminated by drainage and or sealing from the outside.

I have used a similar method to your #1 but starting at the bottom and using a metal tape that was also held in place with a support (2 x4 sections with braces that had a layer of foam sill seal to be compliant, weighted in place not permanently mounted ) I worked my way up close to the ground level. This method for me worked better than any other but the root issue was the water on the wall the opposite wall was at grade.

Opening the foundation drains eliminated the water stuck trying to go down hill and then no more wet wall but the poly foam did help reduce the water and once the water was draining the wall was dry.


The expanding foam repair/epoxy only works with poured foundation walls and shrinkage cracks. If your walls are block, wrong product. I used both low pressure and high pressure foam on my walls and the results have been superb. It was the messiest DIY project I have ever done, but well worth it.


Just for reference:

I have used the poly/epoxy injection systems. They are a bit of a pain in the ass to work with, and they require patience -- the sealant needs to be injected extremely slowly, so it has time to work it's way through the crack, and rushing is guaranteed to make a mess. The manufacturers offer modified caulk guns with springs so you don't make this mistake; they're expensive but if I was doing this again I'd seriously consider one.

Opinion of many, though, seems to be that chiseling the crack to appropriate shape and using hydraulic cement works about equally well. More physical effort, but cheaper and simpler.

However, everyone agrees that the most important thing is to try to move the water farther from your basement to begin with, and that if sloping and exterior drainage aren't sufficient, external waterproofing is by far the most reliable and permanent fix. The former is cheapish and DIYable, the latter expensive and probably a job for a pro.

I sealed what I could, but kept the emergency pump set up because I won't know if the fix really worked until the next "hundred-year flood"... which, with global warming, I'm expecting some time in the next 25 years.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.