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Re: Questions about Residential design and 1997 UBC

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Dennis S. Wish PE wrote:

> 4. Prescriptive Residential Construction Vs New Design
> Standards -I feel that there are a few potential
> problems: A) Conventionally framed homes will not
> calculate (by the number - especially if a raised floor is
> considered) to be of equal or greater strength than
> engineered products. No provisions are made in the '97
> code to strengthen Conventional Framing OR to revise the
> code to correct mistakes and missing information in the
> publication. A loophole in the code exists that will allow
> Conventional Framed homes to be at greater risk AND
> unethical developers will take advantage of the ommissions
> of the code to increase profits on these homes while
> marketing them as equivalent complying products.
> It is true that conventionally framed buildings won't
> "calculate".  So what.  It is how they perform that
> counts.  Conventional construction has a long history of
> satisfactory performance in earthquakes.  Yes, there have
> been failures of older buildings with unbraced cripple
> walls but we have retrofit standards to correct this.
> There is no loophole in the code.  Conventional
> construction was included in the code by the same methods
> as any other provision.  Developers are not unethical to
> use it.  I have never seen any developer market a new
> residence based on its seismic resistance.  The purpose of
> the building code is the protection of the health and
> safety of the general public, not the protection of
> individuals from property damage or economic loss.
> B) As the definition of Conventional Framing increases to
> allow larger and more irregularly shaped structures (not
> load path irregularities) more architects and builders
> will attempt to make larger scale custom homes conform to
> conventional framing standards. This would be
> counter-productive to the intent of the new code
> provisions if the presecriptive measure does not correct
> ommissions.
> The definition of conventional framing has not increased.
> As of the 1994 UBC, the undefined terms "unusual size and
> shape" have been replaced by detailed limits on occupancy,
> dead load, room size (braced line spacing) and degree of
> irregularity.  Additional connection have been required.
> As a result, far fewer building will be able to qualify
> for the use of conventional construction.
> C) Conventional Framing does not require Structural
> Observation provisons which has historically identified
> problems in the construction phase and helped to improve
> quality of construction subsequent to Northridge and
> Hurricane Andrew.
> Structural Observation should not be necessary for
> conventionally framed buildings. An AB 717 qualified (ICBO
> certified) local building inspector should be able to make
> all necessary inspections.
> D) There are no present provisions which requires
> continuous education and training for for framers
> (although the Wood Truss Council of America has been
> backing a framer certification program which is also, as I
> understand it, supported by NAHB).
> The California Contractor's State License Board is also in
> the process of developing a "merit badge" system.
> Are we putting the cart  before the horse by creating more
> regulations to prevent construction quality control
> problems rather than attempting to educate the
> construction industry on interpretation and understanding
> of the conventional framing section of the code?
> Where are "we" creating more regulations that discourage
> quality control?
> Will the greater restrictions posed by the '97 UBC cause
> developers and Architects (designers) to seek closer
> compliance to conventional framing which will produce a
> product designed to a lessor standard than we presently
> have in the '94 code?
> It is unlikely because the more restrictive conventional
> construction provisions will not allow this to happen.
> Ther is however the partially ebgineered, partially
> conventional structures.  This, howver, is not something
> the building code can fix as it would require, in
> California at least, a change to both the engineer's and
> architect's acts.
> With this said, I still believe that there is room for
> improvement in the conventional construction provisisions
> of the UBC, IBC and NEHRP but I also belong to the Frank,
> "where are the bodies", Lew school.  Take a look at all
> the conventionally framed buildings that have ever
> perfrormed so poorly as to cause death or serious injury
> to their occupants and ask yourself would this of occured
> had they been constructed to conform to the current codes
> conventional construction provisions.  To the extent that
> the answer is no, the cuurrent provisions are adequate.
> If you identify any areas where the answer is yes, then
> that is where the code need to be changed.   Anything else
> is regulation for regulation sake.
> Remember, we can always add to the code to make
> construction more expensive but only at significant social
> costs.
> Bob Bossi, PE
> Past Chair, Conventional Construction Task Force