BC Building Code Amended to Reflect Landslide Assessment Guidelines
In January, the Building and Safety Policy Branch issued an information bulletin announcing the amendment of the BC Building Code effective February 1, 2010 to reflect changes related to seismic slope stability. The changes comprise the addition of sentence 4.1.8.16.(8) and sentence 9.4.4.4.(2). As a result:
- The consideration of potential for slope instability and its consequences at a building site becomes an explicit requirement in designs of structures and their foundations; and
- The seismic hazard probability level to be used in the consideration, particularly in assessment of seismic slope stability, will be as referenced in Subsection 1.1.3 of Division B of the BC Building code, namely a 2%-in-50 year probability of exceedance.
Corresponding with the amendment, the Geotechnical Slope Stability (Seismic) Regulation, B.C. Reg. 358/2006 is repealed, and the companion Commentary on Geotechnical Slope Stability (Seismic) Regulation issued by the Building and Safety Policy Branch in January 2007 is also withdrawn. B.C. Reg. 358/2006 served as an interim provision for specifying a seismic hazard probability level for slope assessments for building sites. That level was a 10%-in-50 year probability of exceedance.
The Building and Safety Policy Branch bulletin notes that technical guidance on seismic slope assessment to the 2%-in-50 year seismic hazard probability level can be found in APEGBC’s Guidelines for Legislated Landslide Assessments for Proposed Residential Development in British Columbia. The guidelines provide a risk-based approach to assess and mitigate building sites and to design structures at those sites.
For copies of the Minister’s Orders amending the BC Building Code, see www.housing.gov.bc.ca/building/regs/codes/index.html.