Repair Methods for Foundation Settlement or Vertical Foundation Movement

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Repairs for vertical foundation movement, damage, cracking:

This foundation repair article discusses how to repair vertical foundation movement or foundation settlement using methods to stabilize or even level and straightened a settling or moving foundation wall or floor slab, by using slab jacking, driven steel pins, helical or "screw piers", friction piers or piles or even foundation reconstruction.

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Repair Methods for Vertical Foundation Movement - Foundations, slabs, fireplaces, chimneys

Photograph of a substantial settlement crack in poured concrete.

In the photos shown here, substantive cracks appeared and continued to increase in size in this poured concrete foundation used to support a modular home which had recently been completed.

Photograph of a substantial settlement crack in poured concrete.

The cracks and foundation movement were probably due to a combination of: poorly prepared foundation footings, blasting on an adjacent building lot to prepare that site for new construction, and possibly omission of steel reinforcement in the poured wall. As movement appeared to be ongoing over more than a year, the builder might have repaired the foundation by supporting it from below using one of the methods listed here.

Foundation Repair Using Mud Jacking, Pressure Jacking, Slab jacking Methods

Mud jacking founadtion repair (C) Carson Dunlop Associates

Grout pumping or mud jacking is used to stabilize soils below settling footings or slabs.

The mud jacking or grout pumping method of foundation repair is capable of lifting a slab and possibly some structures.

Mud jacking is suitable if bearing rock or stable soils are not too deep.

For cases where bedrock or suitable stable soils are deeper, slab-jacking methods are usually preferred - see the next foundation repair item just below.

Slab jacking (sketch below) is used to stabilize or lift and level settling concrete slabs, including interior floor slabs poured within the perimeter of a building foundation, and also lifting and leveling of monolithic concrete slabs or slab-on-grade construction.

Photograph of slab jacking.

If a floor slab or slab on grade construction is tipped, settling, or cracking, the underlying cause may vary among poor site preparation such as pouring over un-compacted fill, poor surface water runoff control resulting in soil loss or compaction, expansive clay soils, soil subsidence over buried debris, and sinkholes. [Sketch above provided courtesy of Magnum Piering, Florida.] Contact information for Magnum Piering is at REFERENCES.

[Click to enlarge any image]

Mud jacking schematic (C) Carson Dunlop Associates

Sketch of mud jacking or pressure grouting to lift and repair a concrete floor slab

Carson Dunlop Associates' sketch above shows how slab jacking or mud jacking, also called pressure-grouting, might be used to repair a settling garage floor slab.

Foundation Repair Using Driven Steel Pins

Photograph of Magnum steel pier foundation leveling or jacking.

Driven steel pins are used to stabilize settling foundation walls or footings. A pin is driven next to the foundation and is inserted into the soil until it contacts bedrock.

The driven pin foundation repair method, like the alternative piers listed below, is often used when a portion of a foundation wall is moving or settling, perhaps because of improper site work or footing undermining.

The cost of this method is about $1200. to $1500. per pin for average 30 ft. depth.

The steel pin foundation repair method permits more precise leveling control across the building than grout pumping.

Some reviewers expressed a concern about a possible durability problem? The manufacturers typically warrant the product for 60 years.

[Sketch at left was provided courtesy of Dwyer, Magnum Piering, Florida, via ASHI Seminar 1998, edited by DF.]

Contact information for Magnum Piering is included at REFERENCES.

Helical Pier or Screw-Pier foundation Repair for Settled Footings, Slabs, or Walls

A.B. Chance helical screw piers are an approach similar to the above, but may be shorter in length and useful where soil conditions do not provide shallow bedrock or won't work well with friction piers (below).

Helical anchor pier used to repair foundation settlement (C) Carson Dunlop Associates

Helical piers to repair sinking foundations are often used in building repair or reconstruction, and include models which can be used to level floor slabs as well.

Sketch above provided courtesy of Carson Dunlop Associates [Toronto]. Contact information for A.B. Chance is detailed at REFERENCES.

Friction-Pier or Driven Pier Foundation Repair for Settled Footings, Slabs, or Walls

Friction pier or pile for foundation repair (C) Carson Dunlop Associates

Rod & Steel U-Channel or I-Beam Foundation Repair for Settled Footings, Slabs, or Walls

Rod and steel channel structural repair over bad soils (C) Carson Dunlop Associates

Rod & Channel Repair to Stabilize Structures over Poor Soils. Carson Dunlop Associates' sketch of steel rods and "U" channels illustrates how an engineer may specify a repair to stabilize a building which has been constructed over un-stable soils.

Rod and u-channel structural repairs are more likely to be used where soil conditions prohibit the other pier or jacking methods illustrated above.

Threaded steel rods are run through the width or length of the damaged structure and bolted to vertical steel U-channels on the building exterior.

You may see a similar use of through-building threaded steel rods in 19th century masonry buildings in an attempt to stabilize structural masonry walls.

Instead of "U" channels the rod ends are mounted through steel plates, often in a decorative shape.

Foundation Repair of Settled Footings, Slabs, or Walls by Reconstruction

Reconstruction of foundations: Some engineers who examine a failing foundation may prescribe excavation and reconstruction, possibly with reinforcement over the original design and with additional foundation and site drainage. And indeed in some cases these extensive foundation repair steps are completely appropriate and necessary both to repair the building and to prevent a recurrence of the trouble.

Watch out: We saw this method used for a home in Hyde Park, New York when it was discovered that the home had been built half over a landfill and was suffering from substantial differential settlement.

Helical screw piers or even driven steel pins might have worked at about one tenth the cost of the project as it was designed. We don't know if that alternative was considered.

See FOUNDATION CONTRACTORS, ENGINEERS for advice on how to choose an expert to diagnose or repair a building foundation problem.

Foundation Repair Pier Sources

ECP helical piers are ideal for applications where there is a need to resist a tension or compressive force or both. When combined with an ECP helical bracket, these helical screw anchors are ideal for foundation repair applications.

ECP helical piers have been used in many utility and civil construction projects over the years, from guy wire applications to underpinning and soil nail applications, upon installation helical piers load tested to prove their capacities. Earth Contact Products recommends that only a registered engineer design and oversee the design and application of helical piers when used in foundation repair or new construction projects. Remember, not all helical piers are equal. On your next project make the ECP helical pier your foundation repair solution of choice. Many times helical piers and helical anchors are the best solution for your foundation project due to one of the following factors:

- retrieved 1/29/2014 original source:

Foundation Damage Article Series List


Continue reading at VERTICAL MOVEMENT IN FOUNDATIONS to diagnose and evaluate foundation settlement or vertical foundation movement, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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