Interpretation #7487

Published April 29, 2015

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Original Request

Code Version
2010
Code
RESIDENT
Code Description
Residential
Chapter
18
Section
1803
Topic
Excavation under a structure

Question

Is it the intent of FBC, Section 1803 to require a geotechnical investigation prior to extensive excavation under an existing structure when it is unknown whether pilings support the structure.

Answer Published 04/29/2015 at 1:34 PM

Yes. Please see the attached commentary for additional
explanation.

Commentary

The question refers to Residential and then asks specifically about the Building volume. Since it is not known if the question applies to a building which falls under the Building or Residential volumee, we have assumed the questioner knows the proper volume to request under. See 1803.5.7 which does not give specifics on the type of investigation necessary - it makes reference to enough to "assess the potential consequences and address mitigation measures." This should be a written plan submitted as a part of the project. Excavation near foundations is covered under 1804.1 The section in the Residential volume is R401.1