An Introduction to Spalling

Please see DISCLAIMER below!

Spalling occurs in a CBS (concrete block structure) around the tie beam, along the corners of the building and around the windows and doors. Basically all the places where there is NO block, just concrete poured around a rebar framework. Some flat-roofed CBS homes have a concrete roof, or a concrete floor between the first and second floor (same deal: rebar for structure, concrete poured around it).

You can even have spalling in a poured concrete pad, in an exterior concrete stairwell, anywhere you have concrete poured around rebar.

THE CAUSE: If there is salt in the water/concrete mix (some say just too much water will do it), the rebar corrodes, then flakes and expands, pushing out the concrete and resulting in structural compromise and/or failure.

Spalling can be mild, with just a few bulges or cracks in the exterior of the wall, or it can be severe with chunks of concrete falling out, both inside and outside the home, exposing the rebar. If it gets really bad, the tie beam disintegrates and you lose the structure that is holding your roof on, holding the doors and windows in place... Over the years, I have seen all manner of spalling. In one house, the concrete roof had fallen onto the dining room table. Luckily, no meal was being served at the time...

Also, sometimes you will see spalling in the design elements of the home - decorative columns, planters attached to the house, etc. - but will find none on the actual building. The design elements are generally added later... In my experience, the two are not necessarily connected. Just because you see it one place, does not follow that the entire building is suspect... Your home inspector will be able to tell you how sound the actual structure is today.

Repair of spalling can be minor: chip out the weakened concrete in the affected areas, sand down the rusted rebar, spray it with protectant, then re-cement.

It can be major: prop-up-the-roof, completely remove the tie-beam (or infected area) and completely redo the rebar/cement.

Some say it's not if spalling but when spalling with a CBS home. But we've owned several CBS homes in Key West and none had spalling, all still holding up just fine. I've had several clients and friends who bought property with spalling, repaired it and the problem has not re-occurred.

Don't be scared off of CBS buildings. Unlike wood frame buildings, a CBS home does not rot, termites are way less of an issue, insulation is usually better. And blowing one down is pretty darn hard to do!

The one thing I have learned for sure about spalling is that it's a topic akin to the question, "What causes mold?" Everyone is an expert and everyone (including the experts) has a slightly different explanation and level of concern. I've even heard it called "spalding." Some people wave it off as inconsequential, some are terrified by the tiniest crack or bulge in a wall... study up and make your decision accordingly!

More information:
From the Concrete Center.com
Wikipedia
Brick spalling (slightly different topic, but related)

DISCLAIMER: I am not a construction expert by any means so PLEASE don't rely SOLELY on this information to make your decision to buy or not to buy. The above is to be considered An Introduction to Spalling ONLY!

If you are looking at any home to purchase, have a home inspection completed by an inspector familiar with construction. We recommend George Halloran, 305-296-6108. He has built many homes, both concrete and wood frame, he currently lives in a waterfront CBS home that has seen extensive spalling that he has repaired. I do not make any money for referring him.