Gable end bracing

[inspectagator]

Hey Jerry:

What is the difference between the 2001 FBC and the preceeding code regarding gable end bracing?

Jon Bolton
the INSPECTAGATOR

[Jerry Peck - Codeman]

Hi Jon,

What is the difference between the 2001 FBC and the preceeding code regarding gable end bracing?

The answer depends on what code was used in your area prior to the 2001 Florida Building Code. The 2001 Florida Building Code was based on the 1994/1997 Standard Building Code which most of the state was using. Southeast Florida was using the South Florida Building Code, Dade County Edition or the South Florida Building Code, Broward County Edition, other areas of the state which did not use any of those code mostly used the Uniform Building Code (such as around Gainesville, if I recall correctly).

To best try to answer your question, the following is from the 2001 Florida Building Code regarding gable endwalls.
- From the 2001 Florida Building Code.
- - §2313.4 Gable endwalls.
- - - §2313.4.1 General. Gable endwalls shall be structurally continuous between points of lateral support.
- - - §2313.4.2 Cathedral endwalls. Gable endwalls adjacent to cathedral ceilings shall be continuous from the uppermost floor to the ceiling diaphragm or to the roof diaphragm.
- - - §2313.4.3 Full height studs. Full height studs may be sized using the bracing at a ceiling diaphragm for determining stud length requirements.

The 1994/1997 Standard Building Code did not specifically address the above in the code, however, for 1994 there was the "Deemed To Comply" design manual, which later became SSTD 10. When a structure met the requirements and limitations of size, area, shape, height, etc., the structure code be constructed in accordance with the "Deemed To Comply" (SSTD 10) design manual and was therefore "deemed to comply" with the building code and did not require engineering.

If the structure was not constructed to, or was excluded from, the "Deemed To Comply" (SSTD 10) design manual, the structure was required to be engineered by an engineer of record, signed and sealed.

The above is with conventional framing, when engineered trusses were used, then the engineering for the trusses became the requirements for the installation of the trusses, some engineering included diagonal bracing of gable endwalls back to, and before, 1992 and Hurricane Andrew. Other truss engineering did not include diagonal bracing for gable endwalls until after the reviews of construction failures in Hurricane Andrew was completed - at which time gable endwall bracing became a standard feature of gable endwalls.

The design of that gable endwall bracing has been continually revised through engineering advances since then.

Some gable endwall bracing was simply 'X' bracing, other gable endwall was from the hinge point at the wall below where the gable endwall sets up to the trusses at a 45 degree angle above horizontal to a maximum of 60 degrees above horizontal, with 'T' bracing on gable endwall studs over specified lengths and with the bracing having 'T' bracing when over specified lengths.

As shown above, the answer is beginning to get complicated.

Do you have any specific information which may help narrow the answer down?



Hey Jerry:

Thanks for the quick replies!!! I thought about this after I posted...the question relates specifically to the wind mit form question about does the gable end bracing conform to FBC2001. Almost everything we see is X bracing and I don't remember anything different before.

Jon

[Jerry Peck - Codeman]

Hi Jon,

I thought I would look up and add the following from the SSTD 10-99 (the 1999 version).

The following is from wood framed exterior wall section.
- 307.3 Bracing
- - 307.3.1 When a gable endwall extends from the uppermost floor to the roof sheathing and is not supported by a ceiling diaphragm, andwall roof bracing shall be provided perpendicular to the rafters or trusses in the first two rafter or truss spaces at each end and shall be spaced at 4 ft maximum on center as shown in Figure 307F. Bracing members shall be full depth of rafters or truss top chords. Roof sheathing shall be attached to bracing with panel-end nailing recommendations.

Figure 307 simply shows the bracing at the top chords or rafters going back the first two rafter/truss spaces, the roof sheathing would have been nailed through to these braces. These braces are *not* diagonal or 'X' bracing, just lateral bracing at the top chord.