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Re: IRC Braced Panels

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Properly applied, I believe the IRC can be used in a responsible manner.  It
seems however, that it isn't used correctly in many areas, but that doesn't
mean it shouldn't be used at all.  In the situation you mention (5000 sq.
ft. plus homes with many offset dimensions in plan, many offsets in roof
diaphragm elevations throughout the structure, no load paths to walls, etc,
etc...) engineering judgment would say this is not an appropriate situation
for the use of the IRC.  I am not proposing the IRC be used on custom homes
that are asymmetric and leave very little wall.  I am saying that even in
high risk areas I do believe that symmetric, two-story and less houses with
a healthy dose of walls is a situation where the IRC can be used, and
safely.

Ted Ryan




----- Original Message -----
From: "Joseph Grill" <jrgrill(--nospam--at)cableone.net>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, January 12, 2005 5:18 AM
Subject: Re: IRC Braced Panels


> Ted,
>
> I'll disagree with you here.  From what I have seen the IRC is not fairly
> restricted but extremely abused.  As in my last reply, I have seen way too
> many homes being allowed to be built by the IRC that shouldn't even be
> considered by the building officials.  There are no guidelines in the code
> as to when the IRC can be used other than whether the structure is
"unusual"
> or not.  There is no definition of what is unusual.  Some have said that
> there are definitions to that regard in the seismic section of the IBC,
but
> that is kind of like a definition twice removed.  Building officials won't
> go to the IBC to the seismic sections to restrict a home that is built in
> wind areas when the criteria in the IRC doesn't point them there.  What
they
> see is a simple sentence giving no guidelines for what is unusual and then
> make a judgment from there.  Building officials in my area simply don't
make
> that judgment they just see that is a residence and say OK it can be built
> by the IRC.  I have had architects, designers, and builders come to me
with
> 5000 sq. ft. plus homes with many offset dimensions in plan, many offsets
in
> roof diaphragm elevations throughout the structure, no load paths to
walls,
> etc, etc.  The building official might ask that one or two exterior walls
be
> checked as shear walls, and only then because they may not be the minimum
> length per IRC.  When I have explained this problem to the potential
client
> I have NEVER had one ask for a full lateral analysis.  Why spend a couple
> thousand when a couple hundred will get them their permit?
>
> If the big wind or earthquake does come where then will the liability
fall?
> I can just hear it now "well gee, I had an engineer look at it, and his
name
> is "Brand X" engineering.  See here are his calculations."  And if we
don't
> do it, we engineers in Smallville don't pay our bills.
>
> J. Grill
>
>
> ----- Original Message -----
> From: "Ted Ryan" <coffeemonkey100(--nospam--at)hotmail.com>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Tuesday, January 11, 2005 10:07 PM
> Subject: Re: IRC Braced Panels
>
>
> > 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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