Poured Concrete Wall Crack Repair: Options That Work

Poured concrete foundation walls are strong, but almost all of them crack a little. Usually it's a thin vertical line or two, sometimes with a damp patch after a heavy storm. When you start researching poured concrete wall crack repair, you'll find everything from a tube of filler to excavating around the house, and it's hard to tell which applies to you.

The repair should match the problem. A dry cosmetic crack needs a simple seal. A crack that lets water in needs to be sealed through its full depth or from the outside. A crack from a wall that's moving needs a structural fix. Around the outside of the house, an exterior concrete crack filler on the walkways and slabs next to the wall helps keep water from collecting there in the first place.

The Short Answer

For a dry, stable crack in a poured concrete wall, clean and seal the surface with a non-sag filler made for vertical concrete. For a leaking crack, the usual fixes are crack injection (often polyurethane) or exterior waterproofing, plus drainage improvements. For horizontal cracks, displacement or a bowing wall, have a structural engineer or foundation contractor assess it; those need reinforcement, not sealing.

Why Poured Walls Crack

• Shrinkage as the concrete cures, which creates thin vertical cracks, often near the middle of long walls or at window corners
• Settlement of the footing
• Soil and water pressure pushing on the outside, especially with poor drainage
• Frost in the soil near the top of the wall in cold climates

Match the Repair to the Crack

Dry and stable

Thin, vertical, no moisture, no change over months. Clean it and seal the surface with a non-sag crack filler. That's mainly cosmetic, and it's a good step before painting or finishing.

Damp or leaking

Water on the floor after rain, a damp line, or white mineral deposits along the crack.

• Injection: liquid material is injected through ports along the crack so it fills the full thickness of the wall. Polyurethane is commonly used to seal against water; epoxy is used when bonding the crack is the goal. DIY kits exist, but many homeowners have a pro do it.
• Exterior waterproofing: excavating outside and applying a membrane or sealing the crack from the outside, where the water actually is.
• Drainage: gutters, downspout extensions, grading and sometimes drains, because even a sealed crack is under pressure if water keeps collecting.

Moving or structural

Horizontal cracks, one side pushed in, a bow, or cracks that keep widening. These need an engineer's assessment and usually reinforcement such as straps, braces or anchors, or foundation support.

What a Surface Filler Can and Can't Do

A surface filler seals the face of a dry crack. It looks tidy, keeps dust and some moisture out, and is the right step for cosmetic cracks. It won't stop water under pressure from the outside and won't hold a moving wall together.

Water-activated fillers like the Crack Repair Filler by VALYA are easiest on horizontal surfaces. On a vertical wall, check the product directions, and use a non-sag product if it isn't designed for vertical use. For more on wall cracks generally, see our cement wall crack filler guide.

How to Seal a Dry, Cosmetic Wall Crack

1. Clean the crack with a stiff wire brush and utility knife.
2. Remove efflorescence with a dry brush.
3. Vacuum the dust.
4. Confirm it's dry with the plastic-sheet test: tape plastic over it for a day and check underneath.
5. Press a non-sag filler into the crack with a putty knife, working from the bottom up.
6. Smooth it flush and let it cure before painting.

Outside the Wall

Whatever repair you choose inside, look outside too:

• Extend downspouts well away from the foundation
• Slope soil away from the house
• Seal cracks in patios and walkways that slope toward the wall
• Fill cracks in masonry window well ledges or the top of a block knee wall with a masonry crack filler suited to horizontal surfaces

Mistakes With Poured Wall Cracks

• Surface-sealing a leaking crack and finishing the basement over it
• Ignoring horizontal cracks because they look thin
• Skipping drainage fixes
• Using runny products on a vertical wall
• Not documenting the crack before covering it

FAQ

What's the best way to repair a crack in a poured concrete wall?

It depends on the crack: surface sealing for dry cosmetic cracks, injection or exterior waterproofing for leaks, and structural reinforcement for moving walls.

Can I repair a leaking poured wall crack myself?

DIY injection kits exist, but leaks are often best handled by a waterproofing pro, especially if drainage is the underlying issue.

Are vertical cracks in poured walls normal?

Thin vertical shrinkage cracks are common and usually cosmetic. Watch for leaks, widening or displacement.

Does surface sealing stop basement leaks?

Usually not on its own. Water under pressure from outside needs injection, exterior waterproofing or drainage improvements.

Wrapping Up

Poured concrete wall crack repair works when the method fits the crack: seal dry cosmetic cracks, inject or waterproof leaking ones, and reinforce moving walls with professional help. Always look at drainage outside.

For cracks in the walkways, patios and masonry ledges around your foundation, take a look at the Crack Repair Filler by VALYA.