- Deflection limits for trusses with habitable spaces differ depending upon the building code.
- The 2009 IRC references TPI 1-2007; it defines a live load deflection limit of l/360 for these trusses.
- TPI 1-2002, which the 2006 IRC references, does not contain a live load deflection limit.
- Even if code mandated, automatic sprinklers for one- and two-family dwellings are not required to be installed in every area of the dwelling. With some restrictions, attic spaces, crawl spaces, concealed spaces, closets, pantries, bathrooms, garages, carports, exterior porches and other unheated entry areas do not require fire sprinklers.
- When in doubt about the required location of fire sprinklers, contact your local building official.
- The IRC requires vertical joints in braced wall panel sheathing to be connected to a common stud.
- SBCA has submitted a code change proposal that would allow a wall panels designed to the IRC to be built with the sheathing flush at the edges.
- The proposal will be heard at the May 2010 ICC Final Action Hearings.
- Gypsum board is the most critical element in the fire endurance performance of cold-formed steel and wood truss assemblies.
- When adding insulation to a tested assembly, plan for an equivalent or greater plenum space.
- All softwood lumber used for structural applications in the United States today is produced in accordance with U.S. Department of Commerce Voluntary Product Standard PS 20-05.
- Grading rules for lumber consider the extent, location and number of various characteristics that determine the quality of piece of lumber.
- If it appears that ripping lumber is the only alternative, hire a certified lumber grader to re-grade the material.
- The 2009 IRC contains new provisions in Section R602.10.6 to use blocking for connecting braced wall panels to floor truss and roof framing applications.
- Lateral load can be transferred from bottom chord bearing floor trusses is by attaching wood structural panel wall sheathing to the ends of the trusses, ribbon board, and the top plate of the wall below.
- Section R602.10.6 also includes prescriptive blocking provisions for roof trusses of varying heel heights for seismic design categories and wind speeds.
- Component manufacturers can reduce waste
- The prescriptive method for designing snow load is more conservative than the engineered method.
- The IRC prescriptive method allows the ground snow load to be reduced to 0.7Pg as long as the conditions of this section are met for all truss types.
- The IBC engineered method allows certain reductions to the ground snow load per ASCE 7.
- Truss or rafter uplift connections should be designed for wind load using ASCE 7 MWFRS method, while the member design of the individual truss should use C&C loads to generate member forces.
- Visit http://www.sbcindustry.com/kb/technotes.php for SBCA’s Tech Note on this issue.
- The SBCA Load Guide also contains information about uplift connections for structural building components.
- Information about ceiling space energy requirements from the International Energy Conservation Code is replicated in both the IRC and IBC.
- IRC Section N1102.2.2 applies to ceilings without attic spaces while Section N1102.1 applies to those with attic spaces.
- It is assumed that attic spaces do not require raised heels in order to meet given R-values. Instead, the insulation must be deep enough to achieve it wherever the construction technique allows it.
- SBCA’s Cold-Formed Steel BCSI booklet recommends using material that is a minimum of 33 mil for permanent restraint/bracing applications.
- Framers should verify that they are getting structural grade hat channel (150F125-33) to be in conformance with the industry governing documents.
- If the preference is to use non-structural hat channel, the truss design engineer should evaluate the structural capabilities of the material.
