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RE: History of conventional wood framing- update

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Ken makes a great point. We may be penalizing the purchasers of new homes
for problems that originate in the construction phase - or by the number of
homes designed to a lesser than engineered standard which Ken points out is,
in Los Angeles, called the Type V sheet. This is, essentially, a copy of
what the Architectural Graphic Standard drawing which shows minimum framing
standards for Platform and Balloon framing. The only addition to the type V
sheet is the requirement for minimum braced panel width and spacing as
established in the Conventional Framing section of the '94 code (and prior
codes). The problem is that these minimum standards are "less than" those of
an engineered solution.
As I mentioned in another post, the performance of wood framed structures to
protect life safety issues has been excellent (save those structures which
may have been constructed without insufficient anchorage to a foundation OR
without sufficient lateral restraint of cripple walls below the first
story).
I think that Lynn Howard is also correct to point out that the code "SHOULD"
deal with life safety issues AND the potential buyer/owner should have the
option to decide how the structure should perform.
Many homes are purchased from private builders and developers of a small
number of homes that does not draw the same requirements from a building
official that a large scale builder may be required to comply with. We see
many of these types of homes in the Palm Springs area - developers who
construct less than ten homes a year and do so following a Type V type sheet
because the home complies with the definition of a conventional structure.
In this case the potential buyer is unaware of the standard of performance
which these homes were constructed to and believes them to be equivalent to
those designed under stricter requirements.
This is one of the loop-holes in our codes which become a very unpleasant
surprise to the new home buyer who invests their life savings into their
home.

We certainly need to do more work in fine tuning this code and I'm not sure
that creating stiffer design standards such as rigid diaphragm analysis is
the right answer.

Dennis Wish PE

-----Original Message-----
From: Kenneth Tarlow [mailto:ktarlow(--nospam--at)yahoo.com]
Sent: Monday, February 22, 1999 3:24 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: History of conventional wood framing- update




just reading your posting I have some thoughts.

Most of the type V structures in the San Fernando Valley were
constructed using something called a type V sheet.  Other structures
were designed by Architects, especially custom houses where an
engineer may or may not have been envolved.  Finally a great number of
buildings were designed by Engineers, but were changed in the field,
The contractor having the owner's ear made changes based on the
'bottom line' only.

It was my experience and the experience of other Engineers that well
designed wood framed buildings with well excuted plans, no matter what
the code, performed well. Buildings that sustained the higher rates of
damage were undoublty buildings that were poorly detailed and poorly
constructed.

That is why fiddling with the seismic factors, multiplying Z's and R's
and etc... is kind of missing the point.

Ken Tarlow


---Janiele Maffei <jmaffei(--nospam--at)degenkolb.com> wrote:
>
> Houses that strictly comply with the conventional construction
provisions
> of the UBC have historically afforded their occupants with life
safety.
> However, it is estimated that 75% of the over $12.5 billion in insured
> losses in the Northridge EQ occurred in residential construction.
Taking
> out the apartment complexes constructed over parking that leaves a
> tremendous amount of cracked gypsum board and stucco in low rise
houses.
> Since these structures comprise the primary residence and single
largest
> financial investment for a large portion of our population, perhaps
it is
> appropriate to design them for a higher performance level.
>
> Janiele Maffei
>
>
>
>
>

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