Foundation Settlement in Holbrook 8.2021

Challenge

Introduction: Thank you for allowing Arizona Foundation Solutions to present this foundation survey and assessment for the proposed foundation repairs on your property. The purpose of this report is to evaluate the foundation and the foundation conditions of this property, and to perform a manometer and foundation survey on the interior of the property.

Limitations: This report is based on our observations and may not be indicative of all factors contributing to foundation and floor slab failure. Only a comprehensive geotechnical and structural engineering investigation by licensed engineers would be able to determine all of the factors contributing to the failure of a foundation. Only the areas of concern indicated by our customers, representatives, floor levels, and/or signs of stress are addressed in this report.

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 southern and western portions of the home and at the chimney as shown by the damage (Signs of Stress) and lower readings on the Topographical Map. 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.

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 southern and western portions of the home and at the exterior of the chimney. The slab can then be treated by injecting a light weight 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 it’s Highest Practical Maximum. Using the expansive materials will help prevent additional slab settlement by compacting the upper layer of soil as it expands.

Since storm runoff is responsible for the majority of the moisture that pools next to the foundation, gutters need to be installed and modified 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.