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Stoker Project Basement Wall Repair 3/17/16

March 17th, 2016 by

PROJECT DESCRIPTION

Residential homes around Reno Nevada built between the 1920’s -50’s were typically built with unfinished basements for food, coal, & dry storage.  A fair amount of these basements were constructed with little or no reinforcing steel.  It was not uncommon for the structures that did have reinforcement, to consist of old fence posts, bailing wire, or any other scrap iron a builder could find.  Along with added square footage, basement level foundation systems also served as an added layer of protection for structures built on expansive soils.  The practice was to support the structure on soils well below finished grade so seasonal moisture change (i.e. rain & snow / summertime drying) would not affect the foundation. The Stoker Project was an excellent example of this type of construction.

PROJECT HISTORY

Originally constructed in 1954, the Stoker Project was a single story structure built on a basement that extended under the entire footprint of the upper living area.  The soils in the area are Alluvial Fan Deposits of Peavine Mountain and consist of gravely to sandy clayey silt with andesite fragments common.  These soils are highly expansive and reactive to moisture content.   Water intrusion in the basement had always been a problem for the owner, and over time, the swelling of the clays against the basement walls had pushed hard enough to break the walls and cause structural damage to the framing components.   No reinforcing steel was observed in any of the concrete breaks, some as large as 1” in width.  The rear wall of the basement had a large bow from top to bottom, and was pushing into the interior walls while pulling away from the upper level floor joists.  Damage was significant enough to warrant the installation of temporary shoring supports until VersaGrade repair crews could arrive.

PROJECT DETAILS

VersaGrade was contacted by the Owner to help design the repair plan, & K2 Engineering was retained as the project engineer.  The Owner had constructed a deck and hot tub enclosure along the wall in question that had taken quite a lot of time and effort.  This added a surcharge to the wall which contributed to the walls failure and adjacent interior framing. Our goal was to support the wall in place without demolishing the deck or hot tub enclosure.  As such, all construction operations took place inside the basement.  Because reinforcing steel was not present, a whaler system needed to be installed to help distribute the lateral forces.  Prior to the installation of the whaler, solid steel Ram Jack 1.5” square bar Helical Anchors were installed through the wall using a hand held torque drive motor.  The mid points between the anchor installations were supported vertically by the installation of Fortress Stabilizations ™ – Carbon Fiber support straps.  The straps were epoxied to the concrete wall, & Kevlar straps embedded into the epoxy.  These Kevlar straps were then connected to the structure framing to prevent overturning of the wall.  The final bracing came from the installation of the whaler that consisted of a 10” wide continuous steel channel bolted to the wall & tying the system together.  Even though the space constraints were a challenge, the project was a total success.  The wall had been stabilized, and the Owners hard work on his deck had been saved.

VersaGrade used the Ram Jack Portable Hydraulic Pump and 2.5K Hand Held Drive Motor for the anchor installations.

Total No. of Ram Jack 1.5” Square Bar Helical Anchors Installed: 5

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