Phoenix Foundation Repair 8.2021
Challenge
The Homeowner is concerned with the slab crack in the master bathroom. The Customer is also concerned with the exterior crack on the outside of the master bath, as well as the pinched door leading from the master bath to the exterior. The Customer is planning on staying in the home and would like the issue resolved in order to finish construction on their master bath.
After examining the home and performing the manometer survey, Arizona Foundation Solutions believes the home could be experiencing foundation settlement.
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.
After examining the home and performing the manometer survey, Arizona Foundation Solutions believes the home could be experiencing foundation settlement at the southeastern portion of the home as shown by the damage (also known as signs of stress) and the lower readings on the Topographical Map. The drop off in floor elevations on the topographical map is consistent with a foundation settlement pattern. Foundation 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 also believes the home could be experiencing minor foundation settlement at the northeastern portion of the basement as shown by the lower readings on the Topographical Map.
A minor foundation heave pattern is observed in the southern portion of the home as indicated by the higher elevation readings on the Topographical Map. 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.
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. Deflection and Tilt calculations were performed and compared to allowable values. For this engineered analysis, the deflection of the slab (L/177) exceeds the allowable deflection limit of L/360. In addition, the tilt of the slab (0.16%) was less than the allowable tilt of 1.00%.
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 it’s Highest Practical Maximum. The piles should be spaced approximately six 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 southeastern portion of the home.
Arizona Foundation Solutions believes that the proper way to deal with floor settlement in this instance is to compaction grout the area that is experiencing movement. Compaction grouting is done by coring 2-3” diameter holes in the floor. The holes would be spaced approximately 6 to 8 feet on center. Steel casing is driven to refusal after which low very thick cement grout is pumped under high pressure. The compaction grouting will be located in the southeastern portion of the home. The slab in that area will be raised to its Highest Practical Maximum. Prior to installing compaction grout, AZFS recommends a soil sample be performed to determine what type of grout mix would be necessary.
The minor settlement in the northeastern portion of the basement appear to be minor at this point in time. AZFS does not suggest a settlement repair plan for these areas at this time as there is no significant damage to correspond with the low 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.
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.
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.
