Structural Subcommittee
DEPARTMENT OF BUILDING INSPECTION
City & County of San Francisco
1660 Mission Street, San Francisco, California 94103-2414
CODE ADVISORY COMMITTEE
Regular Meeting of the
Structural Subcommittee
DATE: December 4, 2002 (Wednesday)
TIME: 2:00 p.m. to 4:00 p.m.
LOCATION: 130 Sutter Street, Suite 600 (AIA Office)
This Subcommittee meets regularly on the first Wednesday of each month at 130 Sutter Street, Room 600. (AIA Office). If you wish to be placed on a mailing list for agendas, please call (415) 558-6205.
Note: Public comment is welcome and will be heard during each agenda item. Reference documents relating to agenda are available for review at the 1650 Mission Street, Suite 302. For information, please call David Leung at (415) 558-6033.
draft MINUTES
Present Excused Absent
Jim Guthrie, S.E.
Michael Fretz, S.E.Ned Fennie, A.I.A.
Other Present
Pat Buscovich, S.E.
Hanson Tom, DBI
Yan Yan Chew, DBI
David Leung, DBI
1.0 Call to Order and Roll Call
Members: Ned Fennie, AIA; Jim Guthrie, S.E.; Michael Fretz, S.E.
Meeting was called to order at 2:00 p.m. Quorum established with 3 members present.
2.0 Approval of the minutes of the Structural Subcommittee regular meeting of November 6, 2002.
A motion to approve the minutes as amended. Seconded and approved.
3.0 Discussion on of SFBC Section 3403 on Seismic Triggering.
Discussion on Seismic Triggering was continued with focus on Sec. 3403.2.2
on structural alterations. The current code requires that when more than 30 percent, cumulative since May 21, 1973, of the floor and roof areas of the building or structure have been or are proposed to be involved in substantial structural alteration, the building or structure shall comply with Section 3403.6.
The areas to be counted towards the 30 percent shall be those areas tributary to
the vertical load carrying components (joists, beams, columns, walls and other
structural components) that have been or will be removed, added or altered, as
well as areas such as mezzanines, penthouses, roof structures and infilled courts
and shafts.
Exceptions to this section was discussed. Current code stated that when such
alterations involve only the lowest story of a wood frame building or structure and
Section 3405 does not apply, only the lateral force resisting components in and
below that story need comply with Section 3403.6.
Current code does not differentiate between wood frame or type V and does not
differentiate between multi unit or single family. Basically the current code says
that when you do not more than 30 percent on a wood frame building in the
lowest story, you only trigger a seismic on that story. It gets a little more
complicated when you do the garage and may be one wall above. When you
do 30 percent on the ground floor and 1 percent above, you trigger the seismic
retrofit of the whole building. Permit history to determine cumulative area may
often be required.
Pat Buscovich suggested to change “wood frame” to “Type V”.
Hanson Tom said he did not have any complaint regarding addition of a rumpus
room that triggered seismic retrofit of entire building. When you remove a post
and put rooms in there, it changes the garage basement into living space, with
more occupants on the floor.
However, there are complaints from owners who trigger seismic for removal of post to create additional parking space. There is no increase in number of occupants. In order to encourage people to park inside the building, Hanson wants an exception to release the people who have an intension to remove a post to create parking space, applicable to R-3. Precautions should be
taken not to affect the integrity of the structural frame.
Hanson Tom suggested to add one more exception as follows:
When such alterations involve more than 30 percent of the lowest story used as a
garage of a Type V, R-3 building or structure and Section 3405 does not apply,
that story need not comply with Section 3403.6. When such alterations also
involve more than 30 percent of the tributary floor or roof above the lowest story
of a Type V, R-3 building or structure, the lateral force resisting components of
the entire building or structure need comply with Section 3403.6.
It was suggested to italicize the language to make it ready for the full committee.
Pat would revise the code language as discussed above and email to David Leung who will take care of the italicizing and distribution.
4.0 Special inspection requirements for signs and awnings.
Hanson Tom said he was approached by the president of the awning and signs craft union. They complained about the requirements of our Special Inspection were so extensive that every tiny little signs, tiny awning, tiny canopies for the store front need Special Inspection. Sometime the awning or canopy may cost about $1,000.00, but the Special Inspection costs $500.00. Occasionally, the Special Inspection may even cost more than the cost of whole project. Some jobs cannot be closed because of insufficient fund to pay the Special Inspector.
Concerns were raised on the welding of an awning, which needs some form of periodic inspection.
Hanson Tom said that for big signs, the Special Inspection requirements in the Administrative Bulletin are applicable. He is looking into exemptions for small signs and awnings.
It was suggested that the exempted signs should be of small size and also not too heavy, say 200 lbs or less. If you have 200 lbs, you let the contractor do the task and waive the welder. If it is more than 200 lbs, then you are required to do full inspection.
It was recommended that the contractors have to torque the bolts(expansion bolts or grouted anchors) in and torque wrenchs were very inexpensive. Some concrete screws may be unacceptable under certain conditions.
This subcommittee has consensus that for signs below certain weight say 100 lbs to 200 lbs and under a certain size, on a case-by-case basis the contractor can provide just Special Inspection on the bolts. Welding can be waived.
Hanson Tom would call the president of the awning and signs craft union up and asked him about the proposed size and weight of the exempted signs.
It could be handled with a revision on the Administrative Bulletin for Special Inspection. Hanson Tom said he would do some writeup for further discussion
in next meeting.
5.0 Subcommittee Member and the Staff’s identification of new agenda items, as well as current agenda items to be continued to another subcommittee regular meeting or special meeting. Subcommittee discussion and possible action regarding administrative issue related to building codes.
No new agenda item. Current items 3.0 and 4.0 will be continued in next regular meeting on 2/5/03.
6.0 Public Comment: Public comment will be heard on items not on this agenda but within the jurisdiction of the Code Advisory Committee. Comment time is limited to 3 minutes per person or at the call of the Chair.
No public comment.
7.0 Adjournment.
The meeting was adjourned at 4:00 p.m.