Definition of Spalling and How to Identify It
Spalling is a result of water entering brick, concrete or natural stone and forcing the surface to peel, pop out or flake off. In concrete, spalling happens because there is moisture in the concrete. In basements, especially, moisture and often salt, too, pushes outward from the inside. Eventually, spalling can cause crumbling and destruction of a structure.
A geologist will tell you that salt can cause a rock to explode.
Don't believe me? Read Annals of the Former World by John McPhee.
Spalling in Concrete
It's generally rare to attribute spalling in concrete to the materials used by the contractor. It would more likely be due to the curing process or the way it hardened. Let's talk about how concrete is made, and that might clear up a few misconceptions about concrete.
First, concrete is basically made up of three ingredients:
- Aggregate (which is rock or stones)
People might use the words cement and concrete interchangeably, but the acceptable term for the finished product is concrete. The way I remember this is alphabetically. The word cement contains an M as its third letter, so cement comes first, followed by concrete, with its third letter an N. You mix cement with rocks and water to produce concrete.
Most cement is lime based as in Portland cement, but there are other types of binders. If spalling occurs in a concrete driveway or sidewalk, it typically happens because the weather changed during the hardening process or something else occurred to prevent the concrete from finishing its curing.
Contractors could make the mistake of adding too much water, but most don't make mixing errors.
To fix spalling in concrete, it is not always necessary to tear out the driveway. Sometimes the top layer can be removed with a new layer poured in its place.
Spalling in Foundations
Older homes with basements are the likely candidates for spalling in the basement.
In some cases, the foundation could be brick, which can extract salt in areas of high salt content. In Sacramento, for example, a downtown neighborhood is known as Alkali Flats. Homes in that area were built in the late 1800s and early 1900s, many with brick foundations. Much of the soil contains alkaline.
Moreover, some lending institutions do not want to make mortgages on older homes with brick foundations. Even though those same brick homes have been standing for more than a century without any problems. Always check with your lender and real estate agent to find out if there are prohibitions against obtaining a mortgage on a home with a brick foundation.
Fixing spalling in brick foundations could involve replacing the brick or pouring a concrete retainer wall or tuckpointing. But tuckpointing itself does not alleviate the cracking and breaking off of the walls. Tuckpointing only replaces the mortar between the bricks.
Efflorescence is evident in many wet basements. You can see it on the walls, and if you scrape it with a coin, it will flake like chalk. The way to fix this problem in its entirety is to put in French drains, by digging a trench, lining with rocks, dropping in drain pipe and attaching waterproofing sheets of plastic to the walls.
Sometimes, home sellers try to mask the evidence of a wet basement by painting the concrete walls with a water repellent sealer, which is yet another good reason to always obtain a professional home inspection before buying a home. A home inspector might uncover evidence of a wet basement that is not always evident to the casual observer.
Just because water might be present in a basement does not always mean the foundation is spalling. 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 for more details on how to use a sump pump.
At the time of writing, Elizabeth Weintraub, CalBRE #00697006, is a Broker-Associate at Lyon Real Estate in Sacramento, California.
Also Known As: Flaking, especially in limestone
Common Misspellings: spaulding, spalding
Examples: Due to spalling, some bricks in the foundation had to be replaced because the original bricks had crumbled.