Why I Did This
Not every crack needs sealing. Here's why I chose this one.
The Crack
Vertical crack on my east wall, about three feet long. Hairline to maybe 1/16 inch wide. Classic shrinkage crack from when my house was built in 1978. My monitoring showed it hadn't moved in the three years since I started tracking.
The only issue was slight dampness after heavy rain. Not water dripping through. Just enough moisture to leave a faint stain. Probably didn't need fixing, but it bugged me.
Why Epoxy
I chose epoxy over polyurethane because my crack was dormant. Epoxy sets rigid and creates a structural bond. If the crack were still moving, rigid epoxy would crack again. But mine wasn't moving, so epoxy was the right choice.
Polyurethane stays flexible and handles some movement, but it's not structural. For a stable crack where I wanted both waterproofing and strength restoration, epoxy made sense.
The Learning Opportunity
Honestly, I also wanted to learn how to do this. If I ever had a more serious crack to seal, or if Gary needed help, I wanted to know what I was doing. A low-stakes practice run on a crack that barely needed fixing seemed smart.
The Process
Step by step, exactly how I did it.
The Kit
My $47 kit included six injection ports, a tube of surface sealer (epoxy paste), two cartridges of injection epoxy with a mixing nozzle, and a caulk gun style injector. Basic but complete. Everything I needed for one crack.
Surface Prep
First I cleaned the crack area with a wire brush and then wiped it with rubbing alcohol. Rick had told me the surface has to be clean and dry for the paste to stick. I let it dry overnight because I wasn't in a hurry.
Installing Ports
I glued the injection ports along the crack about every 8 inches. The kit said 6-12 inches. I went closer spacing because I was paranoid about getting complete fill. Each port is a little plastic cone with a flange. The flange gets embedded in the surface paste.
Sealing the Surface
Applied the epoxy paste over the crack between the ports, leaving only the port openings exposed. This seal contains the injection material and forces it into the crack rather than leaking out. Let it cure 24 hours before injecting.
The Injection
Started at the bottom port. Attached the injector and squeezed slowly until epoxy started coming out the next port up. Capped the bottom port with a plug from the kit. Moved to the next port and repeated. Worked my way up the crack until epoxy came out the top port.
The whole injection took maybe 20 minutes. Slow and steady. Not hard, just patient.
Cleanup
Let everything cure for 48 hours. Then I chiseled off the surface paste and the port flanges. Sanded the area smooth-ish. It's not invisible, you can see where the crack was and where the ports were. But it's sealed.
Three Years Later
How has the repair held up?
Zero Moisture
The crack has been completely dry since the repair. No staining after rain, no dampness, nothing. The epoxy sealed it completely. This is the result I wanted.
No Reopening
The repair itself hasn't cracked or separated. If the crack were active, I'd expect to see the epoxy fail or a new crack open nearby. Neither has happened. The dormant crack stays dormant, now with epoxy bonding it together.
Continued Monitoring
I still have pencil marks at the ends of this crack, and I still check it during my inspections. The epoxy repair doesn't stop me from monitoring. The marks are still at the ends. Nothing has moved.
What I'd Do Differently
Lessons from doing it once.
More Patience on Prep
I was eager to start and probably rushed the surface cleaning a bit. Took an extra hour to go back and do it more thoroughly. Should have done it right the first time. Prep is where most DIY failures start.
Better Lighting
My basement is dark. I did this with one flashlight and a camping lantern. Should have set up proper work lights. Hard to tell if the paste is covering the crack evenly when you can barely see.
More Ports
My spacing was 8 inches. I probably could have gone to 10-12 and been fine for a narrow crack. Using all six ports on a three-foot crack was maybe overkill. But better too many than too few.
Less Worry
I was stressed the whole time, worried I was messing it up. Turns out it's pretty forgiving if you follow the steps. The epoxy goes where it needs to go. You just have to be patient and not rush the curing times.
When DIY Makes Sense
And when to hire someone.
Good for DIY
Single dormant cracks in poured concrete. Accessible locations. Hairline to 1/8 inch width. Non-structural cosmetic or waterproofing goals. If you're patient and willing to follow instructions.
My crack was perfect for DIY. Simple, dormant, accessible, not critical.
Hire a Pro
Multiple cracks. Anything structural or safety-critical. Active cracks still moving. Block foundations or irregular crack patterns. Wet conditions where water is actively flowing. Or if you just want it done right with a warranty.
Professional injection costs $300-800 per crack typically. If you value your time at reasonable rates, pro work isn't much more than DIY for a single crack.
Gary's Choice
When Gary needed crack sealing on his floor before the wall anchor job, he had a pro do it. His crack was near where the anchors would go. If the seal failed, it could affect the anchor installation. He paid $650 for professional work with warranty. Smart call.
Epoxy vs. Polyurethane
Choosing the right material.
Use Epoxy When
The crack is dormant and has stopped moving. You want structural strength restored. The crack is dry or at least not actively wet. You're working in poured concrete with a clean, defined crack.
Epoxy bonds the crack faces together. It's stronger than the original concrete. But it's rigid. It can't accommodate movement.
Use Polyurethane When
The crack might still be moving slightly. Water is actively leaking through. You need flexibility more than strength. Primarily waterproofing, not structural repair.
Polyurethane expands as it cures, filling voids. It stays flexible. It works in wet conditions. But it's not as strong as epoxy.
My Situation
My crack was dormant and dry. I wanted both waterproofing and strength restoration. Epoxy was the right call. If I had an active crack or one that was wet during repair, I'd use polyurethane.
Was It Worth It?
Honest assessment after three years.
The Cost
$47 for the kit. Maybe five hours of my time including prep, waiting, and cleanup. Call it $100 total if I value my Saturday at minimum wage. Professional work would have been $400-600. I saved money.
The Result
Crack is sealed. Has been for three years. No moisture, no movement, no problems. Functionally identical to professional work as far as I can tell.
The Knowledge
I learned how to do this. That knowledge is worth something. I helped a friend with his crack last year. Didn't charge him, but I could have. And if I ever have a more serious crack, I'll know whether DIY makes sense or not.
The Truth
The crack probably didn't need sealing. The moisture was minimal. I could have ignored it for another decade. But now it's sealed, it'll never get worse, and I know one more thing about maintaining my house. For $47, that's a good deal.