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Re: IRC Braced Panels

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Again, missing the point.  Regardless of whether the IRC calc's out or not,
homes built in a manner consistent with the IRC generally perform well in
high seismic or wind events.  The IRC takes into account the redundancies
that we aren't able to in design.  The applicability of the IRC is fairly
restricted so that it isn't used in situations where an engineered design is
warranted.

Ted Ryan


----- Original Message ----- 
From: "Dennis S. Wish, PE" <dennis.wish(--nospam--at)verizon.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, January 10, 2005 5:51 PM
Subject: Re: IRC Braced Panels


> I think most of you know my strong views against the IRC (well the UBC
> Section 2320 for Prescriptive light framing) in high risk areas. This
> also includes areas open to high winds that might not be at risk from
> earthquake and wind.
>
> My first complaint is that the braced panel is not required to resist
> overturning by installation of holddowns. I've run an equivalent
> analysis on a small 40-foot wide home with a tile roof and with 4'x8'
> braced panels at 25-feet on center. The load to the panel was sufficient
> to cause an uplift on the wall regardless of the dead load from the clay
> tile roof. In most areas, clay tile is not an issue and asphalt shingle
> is more likely.
>
> The only reference I recall to resisting uplift is if you use an
> alternate braced panel 2'-8" wide up to 10'-0" in height in which case
> it is only required to resist a load of around 1800 pounds of uplift (or
> maybe it was 1500 pounds). The point is that it won't calc out.
>
> So what purpose does it serve to have an engineered code that
> consistently gets more aggressive in designing for better performance by
> using more plywood or proprietary shear walls and more hardware? Given
> the choice, a developer will go for the least cost and greatest profit.
>
> Here is another thing that drives me nuts. Every year I drive from
> California (Palm Springs area) to Chicago. I look at all the new
> developments in Arizona, New Mexico, Texas, Oklahoma, Missouri and
> finally Illinois. The one state that uses the least materials and is at
> the greatest risk is California. The majority of housing tracts that
> I've seen in Arizona and New Mexico will actually sheath the entire
> home. Yes, I believe they still cut back on some of the hardware that
> might help resist uplift, but they are not stingy on sheathing. Yet in
> California you will find tract developers cutting the amount of
> sheathing on prescriptively built homes (those smaller developers who
> are building around ten homes a year) to those large developers catering
> to the more affluent who still want to cut back on sheathing in order to
> maximize profits. They push their engineers (larger tracts are almost
> always engineered) to design with the least materials possible.
> In the heat of an argument with the construction manager for Sunrise
> Corporation, I was told simply that this is a free enterprise system and
> if his engineer can design it with the least materials to pass the
> permit stage he is free to maximize his profit margin for the company he
> works for.
> Yet none of this information is ever disclosed to the home buyer who has
> to pay the price of their deductible (if they have sufficient insurance)
> to cover their out-of-pocket costs.
>
> Look, we know it is not a life safety issue, but the housing industry
> can consider the financial impact poor performance will have on the
> homeowner, the insurance industry and the federal government in grants
> and low interest loans to help pay for the repair for qualified
homeowners.
>
> Is this really justification for a free enterprise system or for
> temporary housing before the cost of real estate rises to house the more
> affluent who will pay even a higher premium for a home built
> prescriptively to the Residential Codes.
>
> Doesn't make a lot of sense to me.
>
> Dennis S. Wish, PE
>
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