concrete Archives - Charles Buell Consulting LLC

There are a couple of obvious things about concrete.

It is heavy and it cracks.

Once the material is laid down, unless you do what is necessary to stop it, it will continue to go down. Like I said—it is heavy.

It is very common, when building houses, to fill around the foundation with materials that are either not easily compacted or can’t be compacted at all—-except over many, many years. Architectural drawings in the past—back when blueprints were actually blue—-use to call out for all fill to be “puddled.” Most builders today probably don’t even know what that means. What it means is that the filled areas were to be flooded with water until there was sufficient puddling on the surface. After all the water disappeared the process was repeated. This was actually a pretty effective way to make sure the ground was compacted enough prior to installation of the “heavy stuff.” Today we would use vibration machines to compact the fill and hopefully use fill that can be compacted—-usually not what is found on site.

Some time ago, I inspected a house with a great example of what happens when the ground around the foundation is not compacted enough.

With this settlement we get to see how unprotected the house structure is. There is inadequate, improper and/or missing house wrap and no pan flashings under the doors. Is it any wonder that these installations result in water intrusion and frequent damage by wood destroying insects?

This installation was lucky—-at least the settlement was fairly uniform—-2 to 3 inches, and roof overhangs were sufficient to keep water away from the openings. When settlement only occurs right next to the foundation the result will be that water will drain toward the home—-creating water issues inside the basement or the crawl space.

After 40 years, nature has likely done what man should have done during construction in terms of settlement of the earth around the foundation. This concrete patio is now a good candidate for slab-jacking.

By Charles Buell, Real Estate Inspections in Seattle

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While Honeycombing of concrete can look like it is being attacked from some sort of creature or chemical, that is rarely the case except in decorative concrete flatwork where the surface has been “released” to reveal the larger aggregate. This is done deliberately by washing the surface with mild etching compounds prior to curing of the concrete surface. It is certainly never the result of bees and the honeycombs associated with them.

When concrete is poured into the foundation forms it does not just flow in like water and fill up the forms to the top. If it is not vibrated properly it may leave voids called “honeycombing.” The exposed aggregate leaves a honeycomb look and hence the name. This first picture is of honeycombing in a footing.

The heavier aggregate is left exposed with very little cement, sand and smaller aggregate that would normally surround the larger aggregate if it had been properly “settled.” This condition is more an indication of poor workmanship than it is a serious structural defect. Severe honeycombing could become serious if it is extensive enough—-but this is pretty rare.

When I was a kid I often had the job of hammering the sides of the forms to help vibrate the concrete into place. In modern construction there are “stingers” to do the same job. They look like a long hose with a salami on the end that is inserted into the wet concrete while it is being poured. The thing vibrates like a BarkaLounger gone wild!

The honeycombing in the following picture is about as extreme as I ever seen it and yet it is still unlikely to be a major structural concern—-even with the exposed rebar. The structural engineer will likely advise patching or nothing at all depending on how likely it is to pose a problem.

So why is this not likely to be a major structural concern even though it looks really nasty?

Well look at it this way—-the entire defect is about 16 inches long and about 4-5 inches tall—-still much smaller than any foundation vent that might be installed in the same wall.

This kind of defect can easily be patched to prevent moisture intrusion and vermin entry to the house structure.

Proper patching will even keep out the concrete eating bees.

Charles Buell, Real Estate Inspections in Seattle

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That sinking feeling….

What is Concrete Honeycombing?