Repairing the Foundation of a Historic Phoenix Home
Challenge
The Owners of this historic 1938 Phoenix bungalow reached out to Arizona Foundation Solutions after noticing several signs of a foundation problem, including movement of the front porch.
An initial Level A Foundation Inspection was completed, and it was determined a Level B Foundation Investigation was needed.
Scope of Services - The extent and scope of this manometer and foundation survey and assessment is detailed as follows:
• Perform a manometer survey.
• Locate the areas of foundation and floor slab failure, if any.
• Visually inspect and record the interior and the exterior of the location.
• Determine the extent of the foundation failure, if any.
• Prepare a documented repair plan if needed.
Foundation Footprint: A drawing of the footprint of the first floor was created and is included in this report.
Exterior Inspection: The exterior of the location was visually inspected. Items such as foundation cracks, exterior wall cracks, improper grading, type of structure, poor drainage, gutters or no gutters, bowed retaining walls, large trees close to the foundation and any type of obstructions that may or may not influence the repair process were noted and recorded.
Interior Inspection: The interior of the location was visually inspected. Items such as floor cracks, wall cracks, ceiling cracks, sloping floors, uneven counter tops, doors and windows that are out of alignment, cracked window glass and bowed walls were noted and recorded.
Manometer Survey: The manometer survey, also known as a floor survey, is a measurement of the differences of interior floor elevations. The flatness of the interior floor was measured using a highly accurate survey device known as a Manometer. The entire interior floor area was surveyed and the elevations were recorded. These data points were then entered into a computer program that provides a topographical map showing the high and low elevation contours of the floor surface. This topographical map shows where the foundation is no longer level and shows where support and stabilization is needed. The floor survey also demonstrates whether any floor slab heave or settlement exists.
Customer’s Concerns/Goals: The Customer’s main concerns are all the ceiling cracks and the cracks on the west side of the front porch.
Solution
After examining the home and performing the manometer survey, Arizona Foundation Solutions believes the home could be experiencing foundation settlement at the central portion of the home as shown by the damage on the Topographical Map and symptoms (Signs of Stress). AZFS believes the home could be experiencing foundation settlement at the southwestern portion of the front porch 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.
AZFS believes the home could be experiencing minor settlement at the northwestern portion of the home as shown by the minor damage (Signs of Stress).
A minor heave pattern is observed in the master suite area as indicated by the higher elevation readings. This phenomenon usually occurs in areas where structures are built on expansive clays. Moisture from one or any combination of the following: storm runoff, poor drainage around the foundation, plumbing leaks and/or underground moisture sources will allow the moisture/vapor to accumulate underneath the foundation. The moisture then interacts with the clayey soils, causing them to swell. The clay soils take the path of least resistance and expand upwards and lift the foundation.
Arizona Foundation Solutions believes that the proper way to permanently stop the 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 foundation up to it’s Highest Practical Maximum. The piles should be spaced approximately five 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 central portion of the home and the southwestern portion of the front porch.
AZFS believes the best way to stabilize the support beams in the crawl space is with Smart Jacks. These are adjustable galvanized supports engineered to be placed under the sagging floors to help prevent settlement of the floor joist system. The Smart Jack sequence should start at approximately 2’ off each perimeter wall and should not be spaced more than 7’ on center (exact spacing to be determined after load bearing calculations). An engineered push pier will be driven concentrically beneath the beam at each Smart Jack location to provide a footing for each Smart Jack. If for whatever reason The installation of concentric piers is not possible, a concrete footing of engineered size will be poured beneath the Smart Jack to distribute the load. The Smart Jacks will then be cut to size and set in place. Finally the units will be adjusted to lift the sagging floors back to their best functioning point or the Highest Practical Maximum.
The settlement in the northwestern portion of the home appears to be minor at this point in time. A protection plan has been designed to stop the area from any additional settlement and further damages. AZFS can permanently stabilize this area to protect the foundation from future settlement at the homeowners discretion.
AZFS does not suggest a heave repair plan at this time as there is no significant damage to correspond with the high elevation readings. The home should be monitored and should damage arise in the future, AZFS should be contacted to perform a comparative monometer survey at a discounted price.
This home should be looked at by a licensed Structural Professional Engineer in order to address the cracking in the southwest column on the front porch. These areas are outside the scope of work of the foundation movement analysis that was performed.
This crawl space plan addresses foundation support. Carpentry and non-soil related movement are outside the scope of work of this project.
Since storm runoff is responsible for the majority of the moisture that pools next to the foundation, gutters need to be installed to prevent the storm runoff from increasing the amount of foundation movement. A proper gutter system should be installed to discharge the storm runoff a minimum of 10 feet, preferably 20 feet away from the foundation. We do not recommend installing gutters that discharge next to the foundation as this will only increase the probability of a foundation problem.
It is also beneficial to manage the moisture around your home using conventional means as outlined below:
Hire a reputable plumbing leak detector and repair service to check both pressure and sewer lines, this is usually done for less than $500. If repairs are needed, they are usually not expensive.
Make sure the grading of the terrain is sloped downwards at 5% slope from the home at all areas of the perimeter.
Stop irrigating plants that are near the foundation and make sure there is nothing trapping the moisture from flowing away from the home.
When permanently stabilizing, lifting and/or mitigating a foundation movement problem, AZFS recommends waiting AT LEAST 6 months before investing in cosmetic repairs.
