What is Cut and Fill and How It Affects Your Foundation

Cut and fill refers to a process by which a sloping area is leveled prior to constructing a building. Specifically, part of the slope is removed (cut away) and the other area is filled with soil, gravel, etc.

If the fill material isn't compacted properly prior to the structure being built, the fill material will compact on its own over subsequent years. What's unfortunate about this is that a slab foundation will move as the fill material compacts. If the fill material is compacted before the slab foundation is poured, then there's little chance the fill will compact even further on its own.

As for the slope that was cut, there may be problems there, too. Chief among these is that clay soil that may have been under other soil is exposed once the area is cut. This allows water access to the clay and, as we've discussed before, water and clay are not good mixtures. Typically, additional water will cause clay soil to expand and the foundation will heave. During droughts, the clay will lose water and shrink, causing the foundation to settle. This expansion and contraction of the clay soil under the slab foundation spells trouble as the slab bucks up and down on the moving soil.

What can you do to prevent these problems? First, you can ask your builder about compacting the soil. In most cased, it's recommended that soil be compacted in layers no greater than four inches. If a layer of soil to be compacted is greater than four inches, it may be too thick to compact adequately before the structure is built. That leaves the rest of the compaction to occur after your home is sitting on the soil — and you don't want that.

Second, you can be proactive and maintain a constant moisture level in the soil supporting your foundation. This means using soaker hoses during the summer when the soil is dry, proper drainage to keep excess water away from the foundation during the Spring and Winter when rain is more common, and installing root barriers to prevent water-seeking tree roots from invading the soil under the house.

Get more information by visiting www.AceFoundation.com.