Denver requirements for shoring excavations associated with residential construction are outlined in the City & County of Denver Community Planning & Development Building Permit Policy, Document ADMIN 130.2A. In addition to the DBCA requirements, excavations will also need to meet OSHA and IRC/IBC requirements.
In general, shoring will be required for any excavation deeper than 4 feet that will be located within 6 feet of a property line unless the adjacent property owner gives written permission for the excavation to extend on to their property. Excavations less than 4′ in-depth do not require a shoring permit as long as the top of the excavation is at least as far from any property line as the excavation is deep. Additionally, excavations with a slope 1.5′ horizontal to 1.0′ vertical or less will not require a permit. A 6′ tall fence restricting access to the excavation area will be required for any excavation over 30″ deep with a slope steeper than 1.5 horizontal to 1.0 vertical.
Before the permit for construction of the structure may be issued, all necessary shoring will need to be permitted, installed, inspected, and final signed off by the Building Inspection Division Construction Inspector must be obtained.
To get started a geotechnical investigation report with excavation/shoring requirements sealed by a Colorado Registered Professional Engineer will be required for any excavation requiring shoring. The geotechnical investigation report should clearly identify the soil type or types present on site and the OSHA requirements for shoring or benching of the on-site soil types.
Shoring on Benching designs for excavations within the City and County of Denver will be reviewed by the residential team if they meet the prescriptive design requirements as described in ADMIN 130.2A. Shoring or benching designs that do not meet the prescriptive design requirements will go through a more thorough commercial review process. All shoring or benching designs will need to be prepared and sealed by a Colorado registered Professional Engineer.
The Denver prescriptive design consists of 10″ diameter reinforced concrete piers spaced at 3′ on center with a depth of embedment below the bottom of excavation equal to the depth of excavation. For a 5′ deep excavation this would require piles 10′ long or for a 10′ excavation the required pile lengths would be 20′. Additionally, an Excavation Bond will be required for any excavation located within 1′ of a 1:1 slope to any public sidewalk, street, alley, or other public property.
At EVstudio, we have experience with the Denver requirements for shoring excavations and have designed both residential prescriptive shoring and commercial engineered shoring in Denver. If you have a project that involves excavation in the Denver Metro area, we can help you to understand the requirements and design a shoring option that meets your budget and time constraints while staying within the Denver, OSHA, and IBC requirements. Contact us today!