Sham Investigations Part II: More smoke and mirrors

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As more homeowners are starting to realize the advantages of having a foundation inspection that is scientific, objective, and thorough, using industry standards, and engineering oversight, the industry is struggling to adapt to these expectations.

I received a phone call the other day from a distraught homeowner. Lets call her Mary. Mary shares a common wall with her neighbor. Like her neighbor, she noticed signs of foundation movement…. Cracks in drywall, sloped floors, and door and windows out of square. A month or so earlier we completed one of our engineered foundation investigations on her common wall neighbor, and Mary  was impressed with the report and felt like she needed to have her foundation investigated as well.  

This is where Mary gets a little sideways. She logically assumed that she could get something comparable from another foundation repair contractor and thus get in effect a 2^nd opinion for both properties. So she had paid for an investigation and waited.

To her chagrin, (according to Mary) a representative showed up and delivered a quote to have geotechnical borings done on her property for $4500. That’s it. Nothing more. I have the greatest respect and admiration for geotechnical engineers and value their input on almost daily basis. But this is not the place to start on a foundation investigation.

According to the Foundation Performance Association and the Texas Chapter of the American Society of Civil Engineers, there are 3 basic levels of a foundation assessment. In short they are:

.                             A. Visual look around and observation of key critical factors (see the document for those factors)

                   B.  Manometer survey, damage map, aerial photos, tilt and deflection analysis (as the main items)

                                C. Full investigation including borings, petrogrphical analysis, Review of all available records and 

                    reports and many more in-depth items.

Level C is usually reserved for legal or insurance cases. Level A is basically to see if there is anything worth investigating.  Level B is where most of the work is done.

Because helical and push piles return soil information that is valuable feedback on soil properties, borings have a limited value on lightly loaded structures as long as the safety factors are high enough to compensate for uncertainty (say like 6 to 1) . Sometimes borings can help with diagnosis when the data on a level B investigation is contradictory, confusing the interpretation. This is fairly rare. From my experience maybe .5% of the time. (1 in 200). 

I hope that the industry in general learns to conduct scientific investigations that are objective, and thorough, using industry standards, and engineering oversight. Even if it means they become better competitors. In the meantime know what you are getting before you pay for it.

Historic Prescott Courthouse Restoration

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Bob,

I am writing to thank you for the excellent work that Arizona Foundation Solutions performed this year on the repair and stabilization of the Yavapai County Courthouse granite stairs. The building will be 100 years old next year and the clock has been  turned back by your crews. To be able to lift these solid granite stairs back into their original position and stabilize them is an impressive feat.  –Bill Otwell, Project Architect

Last year Arizona Foundation Solutions helped restore the Historic Prescott Courthouse. Built in 1916 it is one of the few buildings on the Historic National Register. This restoration required innovative engineering and coordination between the Architect, Engineer and Arizona Foundation Solutions.

The mission was to raise all 4 of the giant stairs, landings, and attached stone walls at each entrance. They had sunk several inches, putting the granite stone steps and granite walls at risk from being damaged and also creating trip hazards. As it turns out all four of these staircases and landings were built on top of the debris of the Famous Whiskey Row Fire of-------. This created a difficult environment to encapsulate and pressurize the soils to raise the structure back to its functioning elevation.

This remodel was required to be done 100% at night due to the fact the courthouse still functions at the counties main courtroom complex. This complicated the already innovative work in that any engineering adjustments would be required to be done by field personnel or wait until morning when no work could be done at the same time. We were told that if we disturbed the court rooms we could be held in contempt of court….. I don’t think they were kidding.

Much of the work was under the steps with low working heights and limited access and tight working conditions. 288 push piles were chosen over helical piles because of their versatility and ability to be installed in very tight access areas including a very low working areas using Foundation Supportworks low profile driving and lifting stands.

The west steps presented a monumental challenge as the weight of the structure included later additions of restrooms that could not have been accurately estimated from the information ahead of time. We lifted with the hydraulic cylinders simultaneously and grouted. The crews pumped grout for about 2 weeks every night with the pressures remaining steady but the structure lifting only marginally. We concluded that the grout was finding new voids in the debris as we continued to apply pressure. Gradually through a series of nightly lifts, allowing the grout from the previous night to harden, the structure was raised using a thixotropic admixture to facilitate blocking of voids.

The project was completed on time and under budget with none of the granite steps or giant blocks being damaged during the process.