Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: History of conventional wood framing.

[Subject Prev][Subject Next][Thread Prev][Thread Next]
I have to agree with Don Carr in his response to conventional construction.
I understand from past discussions with Don what his concerns are regarding
Conventional framing. He is absolutely correct that Conventional framing
complies to a prescriptive method in the building code (at least it does in
the UBC). He is also right on the mark that you can not imply Conventional
construction to be the same as poor quality construction.
Where I do not agree with Don is his last statement that "the codes are
conservative and frequently result in an overbuilt structure."  If this
were, in fact, true, the insurance industry would not have lost so much
money to failures incurred in seismic, high wind and flood type damages.

The building codes (with the exception of the Wood Conventional Framing
section) represents the MINIMUM design standard from which to follow - not
the conservative and frequently overdesigned methods. Conservatism is in the
hands of the engineer hired by the client to use his professional judgement
in the process of design. For example, a box system designed using plywood
shear elements would allow an Rw of 8 to be used in the lateral analysis.
However, few engineers in a high seismic zone would use an Rw greater than
6. This was evident in the threads that we had regarding this matter.
The resounding reason why a professional engineer would use an Rw of 6
rather than 8 is the factor of safety against the unknown problems that
arise in the field by POTENTIALLY poor quality construction. The chances of
finding poor quality construction increases simply because we our clients
award contracts to the lowest bidders. General contractors hirer
sub-contractors based upon lowest bid rather than known ability in much of
the work performed. The only time I have seen this to be different is in
high-end custom homes.

The problem here is one of perception. I am pleased that Don has taken an
active interest in conventional framing issues on the SEAINT listservice.
Don represents the National Association of Home Builders Research Center.
NAHBRC has taken a position more supportive of the builders and with less
intervention by professionals. The problems, as I had clearly stated to Don
in my concerns with a private list of the NAHBRC for REACH (Residential
Engineers and Architects Council on Housing) is that REACH is a closed list.
The list requires a membership in REACH. The Mission statement of REACH is
an admirable task but, in my opinion, is unreachable because it lacks the
open honest debate across professional platforms that is required to make a
truly responsible team of Architects, Engineers, Builders and Building

Finally, the truth is that we have not been able to find a middle ground -
basically an understanding that could have been accomplished by REACH if
they kept their list open to the professional public who have strong
opinions and suggestions about residential construction. Because of this,
building codes ARE starting to become more complicated and restrictive - but
only because there is no attempt to seek a fair solution in the construction
industry. Therefore, the public is the ones who pay for the lack of special
education and certification of those who actually construct structural
systems. Special education and certification systems seems to me to be the
only reasonable solution to qualifying a framer's competency. We certify or
license architects, engineers and inspectors - why not provide some
assurance that the person who reads the plans and lifts the hammer
understands how a structural system is suppose to work?

Don, I hope you don't feel I am trying to attack you or REACH. I think that
REACH is a truly great idea. However, I do not believe that it can achieve
success without opening a dialog with engineers and architects who are not
willing to pay for membership.
What better proof that where you are not debating this issue - on a
public/professional listservice, the SEAINT list.

Dennis S. Wish PE

-----Original Message-----
From: Don Carr [mailto:dcarr(--nospam--at)]
Sent: Friday, February 26, 1999 8:15 AM
To: seaint(--nospam--at)
Subject: Re: History of conventional wood framing.

Reference  History of concentional wood framing

Mostly I just listen but Gary Wheeler's definition of conventional
Framing forces me to jump in.
Conventional framing, in my opinion, is perfectly legal and quite
often quite appropriate, safe, durable, and totally in conformance
with the applicable building code.
Conventional merely implies that the construction is done in
accordance with the prescriptive requirements of the residential
building code.  It does not even exclusively imply wood framing.When
conventional construction is done, it is usually inspected for
compliance with the applicable building code. Any construction can be
done badly, even properly engineered designs. Any construction can be
poorly inspected, even properly engineered designs.  Bad framers and
conventional construction are not the same thing.  Poor quality
construction and conventiona;l construction are also not the same
thing. Let's not make conventional framing a bad thing.  There are
many areas outside of severe seismic and/or high wind areas where
conventional framing is both legal and appropriate.  Don't forget,
the codes are conservative and frequently result in an overbuilt
Don Carr

> "Conventional" as opposed to "Engineered" or specially-designed.
> Conventional implies wood framing built by north american carpenters
> using their "traditional" methods.  2x4 studs 16" on center, three
> studs at each corner, stud walls with double top plate & single
> bottom plate, 4' lap at plate splices,  plate splices over studs
> only, two 16 penny nails endnailed thru plate to each stud, 1x4
> let-in braces at each corner and say 25' apart, etc.   Wood 2x
> rafter and joists per the tables in the building code and toenailed
> to the top plate.  Vernacular construction.  No special inspections.
>  No special plywood nailing patterns, no boundary nailing, no
> collector ties or fancy seismic holdowns.  The only bolts involved
> are the 1/2" anchor bolts 6' on center holding the mudsill to the
> foundation.  No glulams or steel beams.  No engineer or architect
> involved usually, and carpenters can do whatever the owner doesn't
> notice and the inspector okays.
> I guess we should not assume so much when we use the term
> "conventional".
> Gary M. Wheeler, AIA, Architect
> American Architecture Service.  Try our Portal at
>     -----Original Message-----
>     From: Rodrigo Lema <rodrigolema(--nospam--at)>
>     To: seaint <seaint(--nospam--at)>
>     Date: Thursday, February 25, 1999 9:22 PM
>     Subject: History of conventional wood framing.
>    > I hope you understand that, living in a country where wood is
>    not used
> >as a structural material (at least not frequentrly and certainly not in
> >framing), I'm not failiar with certain terms.
> >   I'd like to know what is conventional, I mean conventional as opposed
> >what?
> >    Thanks in advance.
> >
> >    Rodrigo Lema.
Donald L. Carr
NAHB Research Center, Inc.
400 Prince Georges Blvd.
Upper Marlboro, MD 20774
301-249-4000 x575