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Fix concrete that is spalling

We'll confirm spalling, rule out exposed rebar and structural damage, then clean, patch with concrete repair mix, and seal—or tell you when to call a pro.

Troubleshooting · Home maintenance
1–3 hours (plus cure time)
What you'll need
  • Chisel and hammer or small sledge
  • Wire brush or shop vac
  • Concrete repair mix or polymer-modified patch
  • Trowel
  • Penetrating concrete sealer
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Steps

Goal: Confirm spalling, rule out exposed rebar and structural damage, then patch and seal.

Check for exposed rebar

Goal: Rule out damage that needs a professional.

  • Look for rust stains, exposed steel, or areas where the concrete has broken away to reveal rebar.
  • Check the size of the spalled area—several square feet or more may need a pro.
  • Good: Damage is localized and no rebar visible—proceed to Patch path.
  • Bad: Rebar exposed or damage widespread—call a pro.

Patch path

Goal: Remove loose material, patch with concrete repair mix, and seal to prevent further damage.

  • Chip out loose flakes and chips with a chisel and hammer. Remove until you reach solid concrete. Undercut the edges slightly (wider at bottom than top) so the patch keys in.
  • Brush out dust and debris. Dampen the cavity—saturated surface dry (wet but no standing water).
  • Mix concrete repair mix per the product label. Trowel it into the cavity, pressing firmly. Overfill slightly, then strike off flush with the surrounding surface.
  • Keep the patch damp for 24–48 hours per the product label. Cover with plastic or mist with water.
  • Apply a penetrating concrete sealer to the patched area and surrounding concrete.
  • Good: Patch holds and surface is sealed—done.
  • Bad: Patch fails or spalling continues—call a pro.

When to get help

Call a concrete professional if:

  • Rebar is exposed.
  • The spalled area is large or widespread.
  • The damage is on a foundation or structural element.
  • You have patched and it keeps failing.

Confirm you have assessed the extent before calling. For related fixes, see Fix a driveway that has cracks or Fix a driveway that has potholes.

Verification

  • The spalled area is patched and flush with the surrounding surface.
  • The patch is cured and firm—no loose material.
  • The patched area and surrounding concrete are sealed.
  • No exposed rebar; no new spalling in the repaired area.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify spalling—surface flaking or chipping, not cracks.
  2. Rule out structural Check for exposed rebar or widespread damage; call a pro if present.
  3. Chip and clean Remove loose material until you reach solid concrete; clean and dampen.
  4. Patch and cure Apply concrete repair mix, finish flush, cure per product label.
  5. Seal Apply penetrating sealer to patched area and surrounding concrete.
  6. Call a pro Exposed rebar, widespread damage, or structural surface—call a concrete professional.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Location (driveway, patio, steps, foundation)
  • Size of spalled area
  • Whether rebar is exposed
  • Steps already tried

Is the concrete spalling?

Spalling is surface flaking, chipping, or breaking away—you see aggregate or rough patches. Cracks without surface loss are a different problem.

Inspect the surface. Yes: Surface material is missing—proceed to check for rebar. No: If you see cracks only, see Fix a driveway that has cracks or similar.

Yes No

You can change your answer later.

Is rebar exposed or is the damage widespread?

Exposed rebar (rust, steel visible) or large spalled areas (several square feet) need a pro.

Look for rust stains, exposed steel, or large spalled areas. Yes: Call a concrete pro. No: Damage is localized and no rebar visible—proceed to patch.

Yes No

You can change your answer later.

Chip, patch, and seal

Remove loose material, clean and dampen, apply concrete repair mix, cure, then seal.

Chip out loose material until you reach solid concrete. Clean and dampen the cavity. Apply concrete repair mix. Cure per product label. Apply concrete sealer to the patched area and surrounding concrete. Good: Patch holds and surface is sealed. Bad: Patch fails or spalling continues—call a pro.
Question

Patch complete and sealed?

Done

Call a concrete professional

Call a concrete professional if: rebar is exposed; the spalled area is large or widespread; the damage is on a foundation or structural element; or you have patched and it keeps failing. Confirm you have assessed the extent before calling.

Done

Different problem

If you see cracks without surface loss, that is a different problem. See Fix a driveway that has cracks or Fix a wall that has a crack.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why does concrete spall?
Common causes: freeze-thaw cycles (water penetrates, freezes, expands), de-icing salts corroding rebar, water penetration, or poor finishing. Spalling is surface damage—the top layer chips or flakes away.
Can I fix spalling concrete myself?
Yes, for small to moderate areas. Chip loose material, clean the cavity, patch with concrete repair mix, and seal. If rebar is exposed or the damage is widespread, call a concrete professional.
When should I call a pro for spalling concrete?
Call a concrete professional if: rebar is exposed (rust or steel visible); the spalled area is large (several square feet or more); the damage is on a structural element (foundation, load-bearing); or the patch keeps failing.

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