Andy,
If I am reading things right, for SDC A & B you’d simply be governed by the minimum spacing requirements of 25’-0” on center and offset not more than 12’-6” from each end. That works out to a theoretical minimum requirement for one diagonal brace or one 4’-0” wide panel placed at the midpoint of the wall. For a 25’-0” long wall, that provides a bracing percentage of 16% of the building length, which is what you would find in the IRC for SDC A & B.
Of course, thinking practically and from a *wind* standpoint, you actually want at least two braces or panels per line, one at each end of the wall or as close to the end as possible, unless you have a very tight spacing *between* your braced wall lines (say, 5 or 10 feet).
Regards,
Gary J. Ehrlich, PE
Program Manager, Structural Codes & Standards
National Association of Home Builders (NAHB)
ph: 202-266-8545 or 800-368-5242 x8545
fax: 202-266-8369
From: Andy Heigley [mailto:aheigley@jgaeng.com]
Sent: Wednesday, October 17, 2007 10:44 AM
To: Seaint
Subject: IBC Conventional Light Framed Construction
Dear list:
If any of you are familiar with the Conventional Light Framed Construction section 2308 of the IBC 2006, I would like some help.
Braced wall lines are defined in section 2308.9.3 but there is no description, at least that I could find, of what total percentage of wall has to be braced. It refers you to figure 2308.9.3 and I understand minimum spacing, end distances they restrict you too, but in their figure they have Braced wall line L1 as the sum of A+B+C, but doesn’t A+B+C have to be a certain percentage of the total length L1?
It says in Table 2308.9.3(1) that for SDC C that the total length shall not be less than 25% of the building length, but what about SDC A and B?
Just wondering if anybody else has found this and could direct me to the answer.
Thanks in advance,
Andy Heigley