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Re: Wood Framing - Upgrade or Not

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Jeff Smith wrote:

> A few years back San Francisco started enforcing a policy where it was not
> allowed to make seismic improvements unless a complete story upgrade was
> provided from that floor to grade, even if voluntary.

Jeff is correct and the SF requirements (based on SEAONC recommendations) really
didn't work because they were impediments to small budget upgrades.  Except for
correcting soft or weak stories caused by open fronts, SFBC 3403.2.2.2, Item
3(3) requires an entire story including the diaphragm at the boundary to be
upgraded to 75% of current code (1994 UBC) seismic forces.  They current way
around this for wood frame single family dwellings is to obtain an "over the
counter permit" to install plywood, anchor bolts etc.

The SEAONC "Blue Ribbon" committee advising the City has recommended dropping
the full story requirement in favor of the Exception to the third paragraph of
UBC 3403.2 (courtesy of the Structural Engineers Association of Washington).

With regard to additions, San Francisco will still require full building seismic
upgrades with most vertical additions as well as unseperated horizontal
additions that exceed 30% of the floor area base building.

Bob Bossi