Repairing the Foundation on a Historic Home
Challenge
The owners of this historic 1920s Phoenix home reached out to us after noticing several symptoms that indicate a foundation issue.
These symptoms included:
- Interior wall cracks
- sagging floors
- sticking doors and windows
- exterior wall cracks
- floors that are out of level
After examining the home and performing the manometer survey, we believe the home could be experiencing foundation settlement at the central, western and southern portions of the home as shown by the damage and lower readings. The drop off in floor elevations on the topographical map is consistent with a foundation settlement pattern. Settlement can be caused by one or any combination of many factors including sub-grade saturation of moisture due to poor drainage, years of storm runoff, plumbing leaks, improper compaction, the lack of a proper foundation system, and/ or (in most cases) natural earth movement.
After examining the home and performing the manometer survey, Arizona Foundation Solutions believes the home could be experiencing minor foundation settlement at the northern and eastern portions of the home as shown by the signs of stress damage.
The Foundation Performance Association (FPA) "Guidelines for the Evaluation of Foundation Movement for Residential and Other Low-Rise Buildings" were adopted to correlate acceptable and unacceptable distress phenomena with actual survey elevations.
Solution
Arizona Foundation Solutions believes that the proper way to permanently stop the perimeter foundation settlement is to underpin the areas that are experiencing movement. Underpinning is the process of installing deep foundation elements called piles. Piles are engineered foundation supports that are driven down past the unstable soils and are then locked up into load bearing strata, which can support the loads that are transferred to them. Once the piles have been installed, they can be used to lift the perimeter foundation up to its Highest Practical Maximum. The piles should be spaced approximately six to eight feet on center and should start and stop near the hinge points of movement (exact spacing to be determined after load bearing calculations). In this case, the piles would be located at the western and southern portions of the home. The slab at the southern portion of the home can then be treated by injecting a lightweight expansive polyurethane to fill existing voids and lift the floor slab. This is done by drilling small 3/8” holes in the slab after which polyurethane grout is injected directly under the slab to raise it up to its Highest Practical Maximum. Using the expansive materials will help prevent additional slab settlement by compacting the upper layer of soil as it expands.
AZFS believes the best way to stabilize the support beams in the crawl space is with SmartJacks. These are adjustable galvanized supports engineered to be placed under the sagging floors to help prevent settlement of the floor joist system.
The settlement in the northern and eastern portions of the home appears to be minor at this point in time.
Project Summary
Customer Care: Sandra Hernandez
Consultant: Freddy Flores
FER Tech: Jason Larsen
Foreperson - Underpinning: Daniel Alston
Foreperson - Concrete Lifting: Sarah Murillo
