New article: Crack Analysis

This is great info… just inspected a duplex a week ago, built in 1961…1 story, one corner of the building had both horizontal and vertical movement, looked like about 3ft of the corner was just sinking, I agree that in this case, too much info can be dangerous, but I feel it really helps to understand the science behind the problem, I really appreciate the info about rating and identifying the cracks more thoroughly - will definitely help me write a better report.

We offer foundation level surveys with the Zip Level as an option for our inspections here in Texas. Randy, you mentioned foundations are routinely out of level. Especially true with pier and beam foundations on older homes around here but the new construction slab foundations are poured with lasers used to help level them during pour and are mostly pretty accurate. We have expansive, shifting soils around here and over the years many slab foundations do experience settling past the acceptable variance of no more than 1" variance within 30’.

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Jpseph, is “…no more than 1” variance within 30’" a dimension set by a standards organization?

The National Association of Home Builders set it at 1/2" in 20’, last I knew, Kenton.

I run into radial cracks in slabs constantly.
Great information Kenton and Marcel.
Much thanks from this inspector.

Kenton, To answer your question- After 40 years of construction experience the first thing I would say is that here in my parts it’s an industry standard. But also I believe L/360 is the allowable variance / deflection in the IRC for structural floors which equals 5/8" in 20’ or 1" max in 30’.
Also, years back the Texas branch of the Amer. Society of Engineers established the 1/360 ratio as the standard max variance in foundations along with no more than a 1% tilt. Engineers that design the slab foundations around here are also known to use the IRC L/360 ratio for max acceptable variance (of level) on the concrete pour of a slab foundation in their engineered foundation design requirements. That of course has to do with the quality of the pour- not from settling.
We get called out a lot to review settling issues by homeowners for their foundations / structure on homes less than 10 years old. Builders in Texas are liable for the entire structure for 10 years.

Darren, we use the Zip Level for quite a few things. Even commercial property flat TPO roof slopes. Check out our page on Zip Level uses we do. http://www.jwkhomeinspections.com/zip-level-foundation-elevation-survey.html

Thanks Joseph (and Larry).

I thought the engineer who signed off on the plans would be the one responsible for a foundation that didn’t accommodate soil movement since (unless his in-house engineer was the one to approve them) the general contractor is just building to an approved set of plans.
Isn’t the engineer responsible for signing off on a design that takes the result of soils testing into consideration? Why is the general contractor held responsible? I’m assuming by “builder” you mean general contractor and not a developer.

Here is an example of a color coded contour map of a raised foundation slab. Dark blue is the lowest areas and bright yellow is the highest. The left side is the garage slab. The two dark blue areas were settlement due to poor grading, i.e. soft saturated soil. The right side is the floor slab in the house. The large blue area in the middle is due to settlement of a large brick fireplace. It was constructed on the top of the floor slab without a footing.

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Kenton, Yes the Builder (Homebuilder) is the General Contractor - but on new home construction is referred to as ‘Builder’ here in our parts. Yes, the engineer provides the foundation plans, based on soil test & that they sign off on but it’s the Homebuilders product. - Engineer (not in house) is hired by builder. Of course, builder will go back at engineer if there are foundation problems. The engineer designed it, inspected it and certified it. But it’s the Builders product and they are on the hook liability wise for the structural integrity of the home for 10 years in Texas.