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Freezer (Column supports heaved by frost)
Townhouse (Foundation settled)
Residential Foundation Repair (Basement wall bowing in)

FREEZER
Column supports heaved by frost
By Jeff Cvetezar

Foundation Piering Case Study: Foundation Heaved by Frost

The Problem
The structure has experienced incresing amounts of heave throughout the floor due to below slab insulation failing to keep frost from reaching column footings.

Description of Structure
The freezer building is a steel frame structure with aluminum siding built on a 4 foot frost wall with a 12 x 24 x 12 footing.

Project Summary
Frost has advanced 10-12 feet below the original floor elevation under 80% of the area that has heaved. Ice lenses have formed within the frozen zone which is directly beneath the level that interior foundations bear.

Resistance Piering Foundation Restoration Diagram

Foundation Restoration
In each of 24 locations, 6' borings were drilled through an 18" concrete pad and 6-8' of frozen ground. Resistance piers were installed using quiet and vibration free hydraulic equipment. Each pier had a measured bearing capacity rating higher than the working load insuring that future settlement is unlikely. Once all piers were installed, the load was permanently transferred to the piers using hydraulic rams.

Success!
Each pier was installed and field load tested to a verified bearing stratum 46-1/2 feet below ground. The frozen soil was removed and the columns were lowered to their original position.

PROJECT STATISTICS

	Installed By:	RaiseRite Foundation Pier System Inc.
	Number of Piers:	24 resistance
	Part Number:	PP/CLP3500.160M
	Avg. Pier Depth:	43'-6"
	Avg. Drive Force:	50,569 lbs
	Avg Working Load:	22,500
	Ultimate Capacity:	85,000
	Factor of Safety:	2.22 (Drive to Lift)
	(Averages)	3.70 (Ultimate to Lift)

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TOWNHOUSE
Foundation settled
By Jeff Cvetezar

Description of Structure
The project is located in Walker, MN on the shore of Leech Lake. The two unit building, constructed in 1996, is approximately 115' x 50' with a full basement and walk-out facing Leech Lake. The foundation for the structure consists of typical spread footings and masonry block walls. The upper stories are wood frame construction.

Notable Problems

Garage Floor settled in corner
Garage door opening wider at the bottom
Step cracking along mortor joints
Separation of window extensions
Differential movement between sheer-rock and fireplace
Separation of porch and foundation
Interior doors out of square

Project Summary
Based on observations, there is reason to believe that the building is situated above an abandoned railroad embankment. Borings indicate the fill soils placed in 1996 were likely added above existing fill soils placed above compressible swamp deposited materials.

PROJECT STATISTICS

Installed By: RaiseRite Foundation Pier System Inc.

Number of Piers: 45 helical, 24 resistance

Part Number: AP2-3500.165, RD-2875.262, RD-3500.300

Avg. Pier Depth: 60 Feet

Avg. Drive Force: 70,000 lbs

Success!
Tieback helical piers were used to stabilize resistance piers (as shown at right) so that the footing did not push inward when the basement floor was removed. Each pier was installed and field load tested to a verified bearing stratum 60' below grade. The structural load was transferred from unstable soil to the piers. Settlement was recovered and the structure was restored to the approximate original elevation.

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RESIDENTIAL FOUNDATION REPAIR
Basement wall bowing in
By Jeff Cvetezar

Description of Structure
The structure is a one story home with a block foundation.

The Problem
The foundation wall was bowing in approximately 2" on the third course of block from the top. The affected area was 36' long.

Foundation Piering Case Study: Bowed Basement Wall

The Solution
The fill from along the foundation was excavated. Five (5) helical tieback piers were installed every seven (7) feet to anchor the wall, and pull the wall straight. Once the wall was straightened, 3/4" stone was used to back fill, and 12' layer of topsoil was added.

Diagram of Helical Foundation Piering for Bowed Basement Wall

Success!
After each pier was systematically torqued in small increments, the wall was perpendicular and integrity was regained.

PROJECT STATISTICS

	Installed By:	RaiseRite Foundation Pier System Inc.
	Number of Piers:	5 helical tieback
	Part Number:	AHS-SQ1250
	Flight:	8"/10"

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