Foundation Settlement & Foundation Stabilization

Lifting Sinking Residential Homes

Piers installed and a two-story masonry building is lifted. View image		Piers installed at interior and prepared for lifting the building. Interior piers are recommended for 1/2 height foundation walls to counter inward soil pressure. View image

1. Noticeable slopes in the floor framing.
2. Diagonal cracks in foundation walls, wider than 1/8".
3. Cracks in foundation walls which are not uniform in width.
4. Diagonal cracks in the interior drywall over doors or windows.
5. Cracks in the basement or first floor concrete slabs that run parallel to the foundation wall with a slope from the crack location down to the foundation wall.
6. Diagonal cracks in the exterior masonry.
7. Slopes in exterior horizontal siding.

There are four common causes of foundation settlement in the Chicago area.

1. Homes constructed on fill materials which were not properly compacted.
2. Organic material, such as a layer of peat, present under the foundations.
3. Drying and compaction of the soil, also known as soil desiccation, under the foundations.
4. Slope instability. Less common in Chicago area as the land is relatively flat.

Not every settlement problem requires a repair. Determining if stabilization and lifting is required depends on the magnitude of movement, the distress being caused to the building, and the age of the building.

Foundation stabilization and lifting is typically done by one of two methods. The first is to hydraulically push a steel pile into the ground using the weight of the building as a reaction force. The second utilizes a steel shaft with one or more "threads" or helical shaped steel plates at the beginning of the anchor which allow the steel shaft to be turned or screwed into the ground. This anchor relies on the "threads" bearing on stable and adequate soils to support the building loads. Both methods of foundation stabilization and lifting are commonly referred to as piering.

It has been our experience that helical or screw type piers are effective only when the pier can be driven straight into the ground, for example to support a new basement floor constructed as a steel reinforced concrete slab designed to be supported on the piers. Unfortunately because of the equipment required to install a helical or screw type pier it is very difficult to drive the pier straight into the ground next to a foundation wall and the pier ends up going into the ground at an angle. This condition leads to a bending stress being induced into the pier shaft which can lead to failure.

Push, or hydraulically driven piers, can be driven straight into the ground very close to the foundation wall and are therefore more effective at supporting the foundation wall and the building loads on them. Also the capacities of push type piers can far exceed that of helical or screw type piers.

We designed and developed our own push pier system which was covered by three US patents. The technology used in our design can be varied to increase pier capacities to fit almost any application, including heavy multi story commercial buildings. We also have access to several vendors who manufacture and supply the helical or screw type piers.

You may require an engineering consultation if you are not sure that your home or building has a foundation problem which requires repair. A Structural Engineering investigation of your home or building to determine if foundation stabilization is required typically costs $300 to $400. If a report is requested it is an additional $150. Reports are typically required if a home or building is being bought or sold. An estimate to stabilize the foundations is an additional $50. The estimate includes calculating the building loads down to the foundation walls and making sure that the foundation walls have the capacity to carry the building loads from pier to pier. Our objective is to minimize the number of piers required to support the building loads without causing a failure of the foundation wall.

If you own your home and know that you have a foundation problem which requires repair we can generally provide an estimate for doing repair work free of charge.