An underpinning solution to a persistent foundation settlement problem

A persistent foundation settlement problem affecting a fifty-year old house in Wynnewood, Pennsylvania was successfully resolved by intermittent underpinning. This system was selected due to cost and two unique conditions: (1) the bottom of the wall was deteriorated which would have required the added cost of constructing grade beams had pile underpinning been selected; and (2) conventional underpinning would provide access to point and repair the lower part of the wall. In designing the underpinning system, the size, sequence of construction, and spacing of the piers were selected around existing major vertical cracks to minimize structural distress during remediation. Monitoring gauges were installed at critical locations to evaluate the foundation's response during and after the underpinning work. Steel plates or boards were also secured below the bottom of the wall to prevent dislodged masonry units from failing into the underpinning pits. In spite of today's high labor rates and the latest innovations in foundation repair, conventional, labor-intensive underpinning was still the most appropriate and cost-effective remedial scheme to resolve this unique foundation settlement problem.