July 24, 2020

Preparing Your Site and Common Underground Obstructions


Site selection and preparation are keys to a successful building project. Laying the proper groundwork early can help you avoid headaches and long-term problems that can arise from a poorly prepared site.

The areas of most importance when preparing your building site:

  • Drainage
  • Site access
  • Work zone
  • Soil compaction

Consideration should also be given to the building layout, function, accessibility, traffic flow, parking, water drainage or retention, landscaping requirements, buffer zones, local zoning requirements and your long-term happiness with the site. You should also factor in utility connections such as electric, gas, water and septic.

Your building pad must be able to bear the load of a new structure and the site should be prepared to ensure proper drainage.

Soil Types

A layer of course stone over the soil base reduces capillary action and helps drain water away. If the water cannot get away—because fine-grained soil was left in place or was used for fill without a coarse layer of stone placed above it—then capillary action can create serious moisture problems inside your buildings and may contribute to frost heave under floors and approaches. The following images illustrate different site preparation activities based on geographical positioning:

The Building Pad

The building pad is the foundation for the success of your building project. A well-prepared pad will allow you to utilize your building as you will not have ruts to repair and future water issues. Removing the top layer of organic material is a critical first step.

Site preparation consists of the removal of this organic matter, loose topsoil, vegetation, unsuitable soil types, and cutting high areas or filling low areas with well-graded fill that is free of rocks (4” or larger except in column area where maximum size must be 1” or less), free of debris and frost when placed, and can be compacted to 95% of its maximum density. Earth removed from high areas can be used if it meets these specifications.

The following images represent a well-prepared site:

Common Underground Obstructions

Laying the groundwork for your building site also includes evaluating and preparing the soil. Morton Buildings’ exclusive warranty requires a site to be capable of sustaining the weight of the building components plus the water, snow, ice, and wind forces imposed on the building. The quality of your site will also determine the time required for construction, how soon you can occupy the building, the usability of the completed building and your overall long-term satisfaction. The keys to correct soil preparation on your site include:

• Knowing soil and fill materials

• Properly compacting fill material

• Proper excavation and filling/compacting procedures

• Managing water and drainage

• Coordinating with an excavating contractor

The following images illustrate common underground obstructions in a building site that will play a factor in your site preparation activities:

Shallow layer of rock:

Loose fill:

Existing tree roots:

Buried utility lines:

High water table:

Concrete footings, asphalt, rocks, and/or miscellaneous buried items:

If you have additional questions on site prep for your project, contact your local Morton construction center.

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