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Re: Topic: History of Conventional Framing Needed

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                Dennis S. Wish wrote:

             Can anyone confirm this story or provide me with any other stories (or facts) that may have led to the      creation of a prescriptive method?
                Dennis:                Conventional construction as a concept has been around for a long time.  I have documents from the 13th
                Century.      In fact until the turn of the century (the last not the next one) all buildings were designed by rule
                of thumb.  That's why all UMBs have standard all thickness based on number of stories.  Engineering of
                structures was limited to bridges until the development of  reinforced concrete and  the elevator (which led to steel
                frame high-rises) and reinforced concrete.  The common practice of "engineering"  wood frame structures did
                not  take hold until the 1970s.  The following is excerpted from a paper Kelly Cobben, SE and I delivered at a
                Northern California ICBO meeting.  All references are to the 1994 UBC section numbering system.  Please see
                also our technical paper in the September October edition of ICBO's Building Standards Magazine.
 
      History  of Conventional Construction
      A number of the provisions contained in former UBC Section 2517 had been in the code since the 1927 Edition.  The 1949 Edition did not contain Conventional Construction provisions.  However it did require that:  "All exterior walls and main cross stud partitions shall be effectively and thoroughly braced."  In the 1955 through 1967 Editions of the U.B.C., some of the gravity design information contained in Section 2326 was separated from the engineering design provisions.  This section was titled "Wood-Joisted Dwelling Construction" in the 1955-58 Editions and "Light Frame Construction" in the 1961-67 Editions.   The provisions in the section remained substantially the same.  However the text limited the scope to one and two story former Group H, I, and J (current R and U) occupancies.
      Revisions to the 1970 Edition of the U.B.C. incorporated the "Conventional Construction Provisions," which remained very much the same through the 1991 Edition.  What was previously just member spans for gravity load was expanded to become a "stand-alone" construction methodology and was given "deemed to comply" status by the addition of the Exception to what is now Section 1603.1.  Among the items added were anchor bolt requirements, a table of nailing requirements, and wall bracing specifics
      .
      In 1976, the code was changed to add the "unusual size, shape and split level" language that appears through the 1991 Edition.  What is now Table 23-I-W was added to the code in 1988 primarily as a clarification of requirements already in the text of the code.

      At the 1990 A. B. M., the I.C.B.O. membership debated and ultimately rejected a code change that would have placed limitations on the use of Conventional Construction.  The most critical comment was that the change failed to address the fundamental issue: defining what Conventional Construction really was.  Discussion between various members of Northern California chapters as well as S.E.A.O.C. and industry led to an agreement to jointly pursue a solution.  In the fall of 1990, the Conventional Construction Task Force was formed with the goal of reviewing the Conventional Construction provisions in light of current construction practices and developing modifications that would allow more rational and uniformly enforceable provisions.

      During the 1992-93 cycle, two code changes were submitted relating to Conventional Construction.  They were successfully merged into a single code change and, with further modifications at the 1993 A. B. M., form the basis for the Conventional Construction provisions in the 1994 U.B.C.
                 Hope this helps.

                Bob Bossi