What causes vertical foundation cracks?

Most vertical foundation cracks come from two things: concrete shrinking as it cured, and the house settling onto the soil under it. A thin vertical crack, narrower than 1/8 inch, usually means the wall moved a little while the home settled or the concrete dried out. That kind is common and often not urgent. In our area, repair work like crack injection runs $1,000 to $3,000.

Here in New Hampshire we see these all the time. Let us walk you through it.

Why concrete cracks straight up and down

Poured concrete shrinks as it dries. Water leaves the mix, the wall pulls in on itself, and a hairline vertical crack opens up. This often shows in the first year after a pour. A mix with too much water shrinks more, so you get more of them. This Old House covers how normal these shrinkage cracks are.

The other big driver is settling. The dirt under your footings compresses under the weight of the house. As it does, the foundation drops, sometimes a touch unevenly, and a vertical crack forms at a weak spot in the wall. New homes do this as the soil takes the load.

Now add the New Hampshire piece. The soil packed back against your foundation is disturbed backfill, the loose fill that got shoveled back in when the house was built. It drains slow and holds water. Then winter hits. Frost heave pushes on the walls as that wet soil freezes and swells. Year after year, that pressure works on small cracks.

When a vertical crack is no big deal

A thin, stable vertical crack is often just the concrete relaxing. You don’t need a structural fix for that yet. You might not need anything at all beyond keeping water out.

The thing to watch is water. A crack that weeps after a storm is a leak path. Water finds the floor wall joint, the seam where your wall meets the slab, and it pools because that backfill drains so slow. A dry crack today can be a wet basement next spring.

When to take it seriously

Watch for a crack that is wider than 1/8 inch, one that keeps growing, or one that is wider at the top than the bottom. Stair-step or horizontal cracks are a different animal and mean more pressure on the wall. If you see those, get eyes on it.

For a stable vertical crack, the fix is usually crack injection, epoxy or polyurethane, which fills the crack full depth and seals out water. That runs $1,000 to $3,000 and carries a 10-year warranty. If the wall is bowing or under heavy soil load, we step up to carbon-fiber straps at $850 each or a power brace at $1,300 per brace. When the footing itself has dropped, helical piers at $2,700 per pier for the first three, then $2,200 per pier after that stabilize and lift it. We self-perform our structural lifting and helical work in-house, so the same crew owns the job start to finish.

If the crack is leaking and the real problem is a wet basement, the durable answer is interior drainage, our Forever Dry System, not patching the wall alone. We do not do exterior excavation waterproofing. In our experience it fails in about two to three years, and digging up your yard for a fix that short isn’t worth it to us.

We will tell you when you don’t need the big repair. Sometimes a vertical crack just needs sealing and a dry basement, and that is the whole job.

Want a name to ask for? Angel heads up our waterproofing crew.

What it costs

Crack injection is $1,000 to $3,000. Carbon-fiber straps are $850 each. A power brace is $1,300 per brace. Helical piers are $2,700 per pier for the first three, then $2,200 per pier after that. If you’re looking at a full foundation-wall rebuild, we price that after we see it, because no two walls are the same. Financing is available through Hearth, subject to approval, and we make nothing on it.

What drives the number is the length and depth of the crack, how many cracks, whether the wall is moving, and whether water needs to be handled too. We give you a free inspection and a free estimate, with a quote inside 24 hours.

603 Basement Solutions has been trusted by 5,000+ homeowners across New England. We hold a 4.9 Google rating over 250 reviews and an A+ BBB rating. We are licensed and insured.

See our structural and foundation repair work, our foundation repair page, helical piers, and basement waterproofing. Our promise is on the 603 guarantee page.

For more on what foundation cracks mean, the Insurance Information Institute covers home structural coverage basics.

Got a crack you’re staring at? Call us at 603-610-1770 or book your free inspection. We will look, tell you what we see, and tell you if it can wait.

Related questions

Is a vertical foundation crack serious? Often not, if it’s thin and stable. The risk is water getting in. Watch for a crack wider than 1/8 inch or one that keeps growing, and get it looked at if it does.

How do you fix a vertical foundation crack? For a stable crack, epoxy or polyurethane crack injection fills it full depth and seals water out. That runs $1,000 to $3,000 with a 10-year warranty. A moving or bowing wall needs carbon-fiber straps or a power brace.

What is the difference between a vertical and horizontal crack? Vertical cracks usually come from shrinkage or normal settling and are often minor. Horizontal cracks signal soil pressure pushing the wall in, which is more serious. Frost heave on wet backfill drives that pressure here in NH.

Do vertical cracks let water into the basement? They can. A crack becomes a path for water once that disturbed backfill soaks up rain and pools at the floor wall joint. Sealing the crack and keeping the basement dry handles it.