Foundation Repairs That Did Not Work Part II
Another example of an inadequate foundation repair was for a home built on the side of a steep hill which ran down to a creek. It was estimated that the builder brought in over 15 foot of fill material to level the lot prior to installing the foundation. As is usually the case, the fill material was not properly compacted so, over time, the fill material consolidated causing the slab foundation to settle several inches. (Even if the dirt the builder imported – the fill material – had been properly compacted, the foundation would have still settled because gravity, over time, would have pushed the dirt downhill. Only a solid retaining wall would correct this problem.)
Within a few years of moving into his brand new home, the homeowner started noticing indications of foundation settling. This resulted in numerous slab cracks, out of level floors, sheetrock cracks, brick mortar cracks and out of level doors. The homeowner retained a foundation repair contractor to fix the foundation.
The foundation repair company installed about 50 drilled concrete piers that only went to the 12 foot depth. In other words, the piers on half of the home were installed completely within the fill material. Needless to say, the foundation continued to be unstable for several years, requiring continual “adjustment” of the piers. The only remedy for this foundation is to replace the existing piers with piers that are founded in a stable bearing stratum (certainly the piers need to extend at least through the fill material). However, because of the expense, the homeowner has not been able to do so.
It should be said that a post construction pier will typically only prevent vertical movement (downward or settlement movement) and not horizontal movement. Some extreme topographies require a stable retaining wall to stop horizontal movement of the soil.
So, a foundation situated on the side of an extreme slope needs special attention from an experienced engineer who understands soil mechanics.
For more information on foundation movement, go to www.GeoDFW.com