Looking for those DIYers out there. The house that we are buying has 2 hairline cracks in the foundation that were inspected and aren't showing any signs of leakage, and were noted as "normal" but should be "monitored". Well, I want to finish this basement when we close on the house, so I am wondering if anyone has ever patched a hairline crack before?

I have seen those setups where you epoxy tubes along the crack, then seal the crack, and finally inject epoxy into those tubes to fill the crack itself. That is fine, but these 2 cracks are about 12" and 16" each and are quite small and those types of kits seem to start getting a little pricey (about $145 or more) once you factor in the epoxy gun and special pieces.

I didn't know if there was just something simpler that could create a seal to prevent damage and to hopefully prevent the crack from expanding.

Any thoughts on the idea would be great.

Whenever we refinished our concrete pool deck we used a paintable caulk for use on concrete that was suggested, it worked great and the hairline cracks disappeared once the deck was refinished (pool deck paint). Cheap, easy and quick.

We initially tried the concrete patch and ditched that notion after we saw what a PIA it was going to be.

I recently filled in some cracks in my garage floor. I used a two-part epoxy. I found the self mixed epoxy is better for surface cracks as it spreads like drywall compound. I found the first tube I bought wasteful as small cracks were hard to fill and the excess did not re-spread so easily.

I did however go back to tubes as I wanted to seal the space in my garage where the concrete floor meets the concrete walls of the surrounding foundation. It was becoming a home for any bugs that made their way under the automatic garage door. I couldn't master a corner palate knife so tubes were sooooo much quicker and cleaner for this application.

What I used was all paintable but also already pre-colored grey which matched my garage flooring.

Hmmm.... I wonder if the caulk would work. My issue with the 2-part epoxy is that this it is a vertical crack, it would just ooze down the wall and not stay in the crack (this the reason that the "pros" use the attached tubes to squirt the epoxy through after sealing the inside wall to keep the epoxy IN the crack and not ON the crack, or down the wall...)

I wonder if just cramming some sort of caulk into the crack, let it dry, and then apply some of the rubbery sealer over that and to the surrounding areas if that would help keep it all nice and dry. This will end up getting studs, insulation, and drywall, so it doesn't need to look pretty.

I don't think a hairline crack would be a leak worry (yet). Sometime down the road it might, but by then if it was fixed with epoxy, it would just crack beside the old fixed crack anyway. I would consider using caulk as a very temporary fix, at best.

I have one that is about 1/8 inch and it leaks. I'm going to use epoxy on this one.

I sealed a crack in my basement wall, about 10" from the floor upwards.....I first opened the crack to about 3/4" by 3/4 deep with a grinder and masonry wheel/chisel, then cleaned it thoroughly. Dampen the surface. Next I mixed up a small quantity of Xypex slurry which is a crystaline style cement powder that penetrates into the existing concrete. After that, I mixed up some hydraulic cement to fill the crack and after it dried for a day or so, I "painted' it over with a coat of more Xypex slurry. It's held up well for the last 3 yrs....I would say that the epoxy or expanding foam type is probably the better way to go, but it's much more costly and imo a bit difficult for the diy'er. Having a clean crack(!!) is important to get a good bond of whatever you use. I'd also give one of these basement sealer guys a call(expanding foam/epoxy) just to find out what they charge...probably a little pricey, but they should have a lifetime guarantee.

The previous home owners had a floor to ceiling crack on a different wall that was repaired last fall with the epoxy fix with the tubes (straws) to inject it. Came with a 10 year warranty. I think that it cost them like $800. I would hope that the smaller cracks wouldn't be as much, but you never know... I was just hoping to DIY it.

Oh, look at Adrian, doing it "right".

I pretty much agree with CatBrat - if that crack is really going to be a problem, then filling its existing dimensions with ANYTHING isn't going to help you when it spreads and actually becomes a concern later.

OTOH, the other thing that came to mind is Laticrete epoxy grout. You can get it at Lowe's. Minimum buy-in is probably $20-25. You mix the two-part liquid and then add their dry mixture to it. Open time is about 30-40 minutes, but during that time, it works just like regular tile grout, so you can probably jam it into that crack pretty easily with a rubber grout float. When it dries, it's waterproof and about 3000 janka.

My parent's house had a crack in the foundation walls...and it was a finished basement so we couldn't see where the crack was, and didn't know it was the cause for the rainwater flooding for about 3 years. After getting the whole bad sewer line replaced, new sump pumps, new un-leaky escape windows, and ripping up the finished basement, we finally found the small foundation crack....ugh. Be sure you get it done right and save yourself a lot of pain later! Dry basements are happy basements

I've had someone come through my house with a thermal imaging camera. It was to check for draft's, but the cameras can see through finished walls and show you where there are problems. The cameras will show mold or moisture behind drywall, insulation that has fallen (or lack of it), draft's around your house and in your HVAC, and even show hot spots or areas of concern in a fuse panel. The inspection isn't cheap, but it's well worth it IMO.

The gentleman that did the specific area of concern for me, came back with the results that included thermal imaging photographs with detailed information that was all put together in a small binder for me to keep (I still have it, and will gladly scan the results if it's of interest to anyone).

Are they surface cracks or through the wall? High pressure injection is generally the best for large cracks. There isn't any DIY system that works all that well, sorry. I went through this a couple years ago at work and had to bring in a specialty contractor. We tried all kinds of epoxy repairs and they just didn't cut it.

We didn't even notice the cracks but when we had the house inspected, they showed up on the report as not being all the wag through (surface only) and not leaking. Recommended resolution was just to "monitor the area" and no repair was currently needed.

Well that is fine if we weren't going to finish the basement, but I don't want this thing to get bigger once it is inside a finished wall and start leaking 5 years from now. That is why I don't think that the professional crack repair would work because it is just filling in a small crack that isn't very deep. I doubt that they could inject the epoxy into the crack after sealing it up and putting the straw like injection tubes in place. The seal would probably just go into the crack and leave no open spAce for the epoxy to be injected to.

Maybe I am making a bigger deal out of it than needs be.
On a side note it is a walkout ranch that was built 12 years ago so hopefully everything has settled for the most part.

My house was 50 some years old before the basement walls started to crack.

So true.

I think sealing the crack from the outside is more effective, but if this one isn't showing on the outside then you might not need to worry about it.

Our first house had a few small cracks in the poured foundation. Talked to a foundation guy and he said even if you patch it, if you have a water issue it will finds it way through the cement/floor anyway. How old is the house? Cosmetic cracks are not unusual, look at side walks and driveways.

I would make sure that your foundation around your house is graded/slopes "away" so water doesn't collect next to your house. Do you have a sump pump?

House is 12 years old, and the cracks are "under" the garage area. By that I mean that the particular foundation wall is shared with the inside (connected to the house) part of the garage, so you can't slope away from it there, but the yard does slope nicely away all around. There is a sump pump as well....

Nick: If they're more than 1/4" wide, there are many, and/or they're very long, get a basement pro's consult first.

Otherwise, use hydraulic cement. Technically, they need to be fixed from the outside, which an be a costly horror of digging up the yard around your house.

Mine, of course, are directly under the deck. It would have to get ripped out to reach those areas.

Your own repairs will fail every few years. Just redo as needed.

When patches are done, use UGL brand waterlock prime. No other brand actually works.

There was a guy named Earl Proulx who gave advice for years in Yankee magazine. He died. I think I have a replacement to nominate.

The cracks are very small... Probably less than 1/8" if that wide, and about a foot long for one, and about 18 inches for the other. Since the "outside" of the wall is under the garage, there is no way to get to that side of the wall.

So the trick becomes that if I need to keep patching, it will end up behind a finished wall right in the main part of the basement. Again, it isn't leaking or anything, I am just wondering if there is anything "preventative" that I can do to try to assist in preventing it from getting any worse.