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RE: Single Family Housing Design

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The design of residential homes in California may be done without the
signiture of either a licensed architect or engineer provided it conforms to
the guidlines of Conventional Framing standards established in the Uniform
Building Code section 2320 of the 1997 code. There are restriction that
include location and spacing of minimum shear walls (braced panels) as well
as regularity in plan. In our area of Palm Springs California, very few
homes in the One Million dollar range would conform to this section of code
since most contain plan irregularities (where shearwalls are eccentric or
non-linear OR where multi-story shear elements do not stack. In addition,
very few custom homes in our area contain sufficient plywood shear walls and
usually require an alternative lateral restraint system such as moment frame
or flag-pole type columns.

Please search the SEAint Archives inasmuch as there is a great deal of
comment (much of which is mine) related to conventional framing pros and
cons.

As far as the issue of the building official allowing an engineer or
architect to design a portion of the structure, this is true here in
California. However, it is my opinion that any professional who places his
stamp on a drawing with the intent of designing only an element is opening
him/herself up to some serious liability potential. The building official
may allow it, but assumes no responsibility for it in the end.

I urge you to review the list archive regarding this matter. It is not only
relevant to high seismic area's, but is relevant to any area govened by wind
or other forces of nature.

It boils down to the an issue of ecconomics and one of construction quality.
Consider the following:
1. Few wood homes collapes, however many experience costly damage that may
be avoided had an engineer been hired who has specific knowledge of the
performance of materials.
2. Conventional framing standards is not an engineering solution, but a
comprimise between a number of interested lobbiest - including the AIA,
Insurance Industry (who is not a strong proponent of Conventional Framing),
the National Association of Home Builders (a construction lobby) and others
who wish to reduce construction cost and do not understand the benifit of
performance based structures.
3. Most building offials believe that contractor understands and complies
with the specific requirments of conventional framing. The fact is that the
contractors licensing exams in all states (as far as I am aware) does not
reqire the contractor or his framer to have read the code, nor do they test
the framer as to the minimum building requirments presented in this section
of code. Therefore, unless the building inspector is specifically trained in
structural issues, load paths are probably no properly tied (as I have seen
in my area of the country).
4. Conventional framing standards is not as restrictive as the design
produced by an engineer using the same load criteria. Conventional framing
is not really a minimum standard since it does not comply with minimum
requirements from the engineering mathmatics. This leads to fewer mechanical
connections such as hold-downs (tension ties), anchor bolts and shearwalls.
This allows the developer of Conventionally framed homes to market his
product as being equivalent to the homes being sold that have been carefully
designed by professional engineers. This is, in my opinion, unethicial since
the buyer is unaware of the potentially high cost of repair that they will
suffer compared to the same style home designed by an engineer. This is
where the "bottom-feeders" rape the market by maximizing their profit
margins and providing what I consider is less than minimum standard of
quality for residential construction.

I need to preface my comments by saying that they do not apply to certain
types of homes - especially those in the mid-west where exterior brick is
commonly used. These homes are in areas of low seismic activity and the
weight of their veneer is generally enough to compensate for wind pressure.
However, once you are outside of a major metropolitan market that has access
to brick you will see more homes constructed of either wood frame with
stucco or some other type of Shiplap type siding. These homes are effected
by wind.
We live in an era where the "Fat" is cut out of everything - from our jobs,
to our income and the quality of the homes being constructed today.
Engineering, too, is controled by the computer era which allows us to design
to the most ecconomical designs. I believe that if we have taken away all of
the room for error or unknowns, we had better place the design and detailing
in the hands of a professional who understands how the system works. The
upfront cost will more than compensate the home owner in the future should a
natural disaster occur (how common are hurricanes, tornados and
earthquakes).

Finally, if we construct based upon a minimum standard, the prospective
buyer has the right to understand how this minimum performance can effect
them in future years. The alternative is to require professional
intervention unless the product is designed for the homeowner. In this case,
the homeowner has the right to choose the level of safety they wish to own.
Otherwise, the developer profits from the owners potential misfortune.

Dennis S. Wish PE