What Causes Concrete to Sink?

Interwest Concrete Lifting is dedicated to returning sunken concrete slabs, steps, and columns to their original elevations. Interwest Concrete Lifting can best enhance customer satisfaction when we remove trip hazards, fill voids under concrete slabs, and lift concrete back to the level it was in the beginning. These concrete problems are widespread in Salt Lake and Utah counties.

The Factors

Their causes come from a wide range of factors. The most prevalent of these factors can be identified.

1. Inadequate soil compaction during the construction phase is a leading cause of subsurface settlement. Concrete basement walls of eight to ten feet generally require that same depth of compacted backfill. A walk out basement will reduce the amount of compaction needed. Depending on the soil type, it can take up to 7 years for these problems to stabilize.
2. Improper drainage away from a downspout is another major factor. Settlement of adjacent soils creates enough weight onto the downspout drainage pipe to separate the downspout connections, or brake the drainage pipe. Each subsequent rainstorm dumps volumes of water and floods all concrete slabs in the area of the downspout. This flooding of soil next to a foundation will cause negative drainage away from the building and a pond of water will occur. This amount of excess water under concrete slabs will cause settlement. Along with settling, large voids appear under the concrete which weakens support. Concrete is heavy; weights up to 4000 lbs. per 80 square feet. Cracks will appear in these unsupported areas.
3. Landscaping settlement along the edges of concrete slabs allowing surface water to penetrate under the slabs. This problem may cause slabs to tilt and crack. Open voids will appear, further destabilizing concrete slabs.

How to Prevent Sinking Concrete

Prevention is the best solution. The homeowner does not always have control over installation at the time of construction. Preventive measures will help head off trouble such as:

1. Repair broken downspout connections and broken drainage pipes as soon as they occur.
2. When settlement occurs next to the foundation, add topsoil to keep a two percent drainage grade away from the house. Avoid water accumulations next to foundations and concrete slabs.
3. Interwest Concrete Lifting has good solutions for filling voids before they expand and crack the concrete slabs.
4. When settlement does take place, Interwest Concrete Lifting has long term sub grade replacement. Injecting a formulated grout mix will lift and stabilize concrete slabs back in place. This is an excellent long term solution and more economical than tearing out and replacing concrete.
5. Make a decision early for concrete stabilization. Interwest Concrete Lifting estimates are free. Evaluate as soon as the problems start to occur and before cracking and damage takes place.