What Is Spalling and How Can You Identify It?

Excessive spalling can cause a structure to crumble

The exposed foundation of a house

​ OliverChilds / Getty Images

Spalling—sometimes incorrectly called "spaulding" or "spalding"—is the result of water entering brick, concrete, or natural stone. It forces the surface to peel, pop out, or flake off. It's also known as flaking, especially in limestone.

Spalling happens in concrete because of moisture in the concrete. Moisture—and often salt, too—push outward from the inside in basements especially. Spalling can eventually cause crumbling and destruction of a structure.

Key Takeaways

  • Spalling is what happens when water enters brick, concrete, or natural stone, especially if a curing process is involved.
  • Spalling forces the surface to peel, pop out, or flake off.
  • Older homes are more likely to have spalling in their basements, particularly those with brick foundations.
  • Even if water is present in a basement, it doesn't necessarily mean that the foundation is spalling.

What Causes Spalling?

Spalling can occur for a number of reasons. In particular, salt, particularly the sodium chloride that's used on frozen roads in many northern states, can cause oxidation or rusting of reinforcing steel when it's repeatedly introduced via water to a surface or building.

Spalling can also occur due to fire exposure, general freeze and thaw cycles, low quality or poor depth of concrete over reinforcing bars, poor construction, and more. Whatever the cause, it's important to address it quickly.

Spalling in Concrete

It's generally rare to attribute spalling in concrete to the specific materials a contractor used, although excess water can be a culprit. Knowing how concrete is made can help clear up some misconceptions.

People sometimes use the words "cement" and "concrete" interchangeably, but the acceptable term for the finished product is concrete.

Concrete consists of three basic ingredients:

  1. Aggregate—which can be either rock or stones
  2. Water
  3. Cement

Spalling that occurs in a concrete driveway or sidewalk typically happens because the weather changed during the hardening process or something else occurred to prevent the concrete from finishing its curing. Contractors might also make the mistake of adding too much water or using water to try to accelerate the finishing process.

Tearing out the driveway isn't always necessary to fix spalling in concrete. Sometimes the top layer can be removed, and a new layer poured in its place.

Spalling in Foundations

Older homes are likely candidates for spalling in their basements. The foundation might be brick, and this can absorb moisture and extract salt in areas with high salt content.

It could be difficult to secure a mortgage on a house with an older brick foundation. Always check with your lender and real estate agent to find out about prohibitions against mortgages on a home with a brick foundation.

Fixing spalling in brick foundations can involve replacing the brick, pouring a concrete retaining wall, or tuckpointing. But tuckpointing itself doesn't always alleviate the cracking and breaking off of the walls.

Tuckpointing only replaces the mortar between the bricks and helps prevent further moisture intrusion.

Watch for Efflorescence

Efflorescence is evident in many wet basements and can be a precursor to spalling. This is a visible buildup of salt that has transferred through concrete or brick in water that has since evaporated. You can see it on the walls, and it will flake like chalk if you scrape it with a coin.

This problem can be fixed with certain acids or pressurized water and then prevented with perimeter drains, or hydrophobic sealants. Consult a masonry expert for the best approach if you see signs of efflorescence in your basement.

Don't Skip the Home Inspection

Home sellers sometimes try to mask the evidence of a wet basement by painting the concrete walls with a water-repellent sealer. This attempt to conceal problems is one of several very good reasons to always obtain a professional home inspection before buying a home. A home inspector might uncover evidence of a wet basement that isn't always obvious to the casual observer.

On the other hand, it doesn't necessarily mean that the foundation is spalling just because water might be present in a basement. Some homeowners may install and use sump pumps to reduce water levels in the basement and to pump out excess water during a rainstorm. Check with your home inspector regarding any concerns about water intrusion in the basement.