"Punch List" Inspection Prevents Disaster
Owners of a newly-built, luxury custom home on a desert hillside in north Phoenix called on The Klingler Group to help resolve a dispute over unfinished work. The homeowners' "punch list" of items left unfinished at first appeared to contain relatively minor issues that could be resolved at minimal cost. But after another visit in which we walked the property with the homeowners and heard how disappointed they were, we discovered that something was, in fact, seriously amiss.
During the second visit, the owners pointed out that the circumference of the circular driveway was not as large as what was designed or anticipated. As a result of the reduced size, the design would no longer accommodate a fountain that was to be placed at the center.
This circular drive was located at the back, or east side of the home, which was also where the toe of the hillside slope and the top of the building pad met. Initially, we believed the reduced space could be a result of the builder choosing to place the footprint of the home further back on the pad. But as the homeowner pointed out, the patio at the front, or west facing side, which made up the leading edge of the building pad (held in place by a masonry retaining wall) was also much narrower than anticipated. The width of the patio was reduced by approximately 15 feet, for a total reduction in both front and back equating to a pad size reduction of more than 20 feet. It was apparent that the pad was too small for the home that had been constructed upon it.
Since there was no explanation as to why the change in pad size had occurred, we looked deeper into the design to insure that compliance had been met. We found that the pad created by cutting into the hillside had not been graded to meet the original design. We further found that zoning restrictions had inhibited extending the pad onto a non-buildable area of the property. This reduced the area of the pad substantially; unfortunately, the home was not similarly reduced in size. Given the limited setback from the retaining wall to foundation line, we recommended that further analysis be conducted to look into the structural integrity of the building's foundations.
SERIOUS CONCERNS IDENTIFIED
As we looked further into the placement of the home, we discovered that a section of the foundation rested on and also cantilevered over a portion of the retaining wall. Crack patterns exhibited in this area as well as in other locations suggested that the structure was not only unsound, but was beginning to slip down and away from the hillside.
We also evaluated any and all distress patterns found throughout the patio hardscape, pool, spa and retaining walls. Some of these areas exhibited stress fractures and soil consolidation, as well as fissures. This finding reinforced our belief that soil creep was occurring at the fill sections of the building pad.
Further investigation revealed the retaining walls had not been engineered or designed properly, and lacked adequate reinforcement. Our investigation also found that, as a result of poor surface and sub-surface drainage, the retaining walls were subject to excessive pressures that in time would lead to catastrophic failure. Abnormal distress patterns showed that movement, or wall overturning, had already begun.
RETAINING WALL REPAIRS
Once we determined that the soils below the existing slab and the exterior foundations placed in fill soil would need to be stabilized, we developed a repair plan. The repairs, performed by Arizona Ram Jack (ARJ), consisted of tying back or stabilizing the walls with the use of injection-bored soil nails. Among other things, the repairs also consisted of grouting below sections of the unsupported foundations. By eliminating concerns over wall failure and soil creep, the repairs and augmentation of the retaining walls made up for the oversight of the builder and ensured the integrity and value of the home.
In this case, what began as a "punch list" of minor matters led, on deeper inspection, to the discovery of major structural problems. The case demonstrates the importance of comprehensive investigation by people with proper construction knowledge and backgrounds. We often get asked to look into complaints regarding soil subsidence or heaving, as well as concrete fractures and distress. More often than not, these issues are found to be superficial in nature. With this home, however, our team of professional engineers and construction experts was able to identify and correct real deficiencies, thus limiting the damage and preventing an almost certain disaster.
Building corner extends over retaining wall.
Close-up of corner extending over retaining wall.
Stress crack in retaining wall indicates potential failure.
Section of retaining wall to be repaired.
Repair of retaining wall using soil nails.