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Land – The Beginning of Your Custom Home Journey (Part 2)

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The land a customer chooses to build on also has profound implications on the technical building aspects and costs of the custom home. The design, complexity, and cost of your home’s foundation is dependent upon the soils in which it resides. As such, Tuscany Homes will always conduct a soils test on the proposed location of your home.

A soils test is a test conducted by an independent geotechnical engineering firm. They drill two cores approximately two inches wide down to a depth of 15-20 feet. The geotechnical engineers then examine and test the soils in order to determine the geological composition of your soil and how it will affect the foundation of your custom home. The soils report is normally completed within 10-14 days of the test and includes not only information about the soils, but also the engineer’s recommendation on the design of your home’s foundation. If the soils test results in a finding of expansive[1] soils, additional design elements will be added to your foundation to account for these phenomena[2].

Expansive soils are soils that have the potential to move, heave, or expand (usually through water absorption, although other causes do occur) to the degree that it will cause the foundation of the house to shift, often causing moderate or severe damage to the house.

Unfortunately, in Colorado, and specifically throughout Colorado Springs, there is an abundance of expansive and unstable soils. As such, many of our home designs require additional foundation design elements to address these conditions. The two most common methods of addressing expansive soils in Colorado Springs are overdigging or caissons.

 These two techniques are summarized below:

  • Overdig. The most common method for addressing expansive soils is overdigging. Overdigging is the removal of additional soil material around the proposed foundation of the house and replacing it with “clean fill”; that is soil that is not expansive or unstable. In this manner, the house sits on soil that will not move, and any movement from expansive or unstable soils is absorbed by the “clean fill” and not transferred to the foundation.
  • Caissons. A caisson is a reinforced concrete post that transfers the load (weight) of the home directly to bedrock[3]. The foundation of the house sits on the concrete posts and holds the weight of the house off the unstable or expansive soils. This technique allows the soils to move around the house without moving the foundation and causing damage to the custom home.

Unfortunately, any mitigation of expansive soils is an additional expense in the budget of the home.   Overdigging requires additional excavation and trucking of material to and from the job site. Caissons require specialized engineering techniques and significant drilling. Both techniques add both costs and time to your custom home project. Such costs and delays however, if they are required, should be considered against the value of the land as described in Part 1 of this discussion.

Tuscany Homes is the premier custom design build homebuilder in central Colorado. You can find our custom homes in the premier neighborhoods of Colorado Springs, Woodland Park, Castle Rock, and Denver. Copyright 2015 ©.

[1] Also referred to as active soils, unstable soils, or by specific soil types.

[2] Additional tests and inspections are done at the time of excavation when the entire building envelope is viewable by the geotechnical engineers. At that time, additional modifications may be made to the foundation design by the engineers.

[3] http://www.home-building-answers.com/caissons.html

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