Residential Codes (IRC)

Deflection Of Long Span Scissors Trusses

Question: 

I was wondering if you have any information or anecdotes relating to the deflection performance of long span scissors trusses? We recently sold a job with 70 ft. long scissors trusses. The customer is in the process of installing the trusses and doesn't like the deflections he is seeing. To make matters worse, the scissors trusses are framing into a valley set (which we provided) that is erected on 35 ft. Howe trusses. The Howe trusses are exhibiting very little deflection. Any ideas?

Vent Sizes

Question: 

I have mono trusses on either side of a firewall. I have the fire rating/wall material between them. Can I place a ridge vent above these two? Or should I use vents? How do I calculate the appropriate vent sizes and styles?

Ga Rc 2601

Question: 

In RC 2601, is RC-1 Channel used?

Responsibility For Multi Ply Girder Truss Assembly

Question: 

I am reviewing a truss package that includes multi-ply trusses. Where do I find the requirements for the attachment of the individual trusses to each other (nails and/or bolts)? Is this a requirement that the structural engineer of record needs to supply or is it the responsibility of the truss manufacturer to design?

Duct And Light Penetrations Of Fire Rated Assemblies

Question: 

In a small scale multi-family residential project, I'd like to use a wood truss floor-ceiling assembly to achieve a one hour separation between units. I'd like to directly attach the drywall to the underside of the trusses & use the truss space for ducts & lighting (the floor above will be lightweight concrete on plywood sub-floor). UL assemblies do not seem to address the duct/light penetrations in such an assembly. Can I achieve a one-hour rating in such an assembly and how are penetrations addressed? Can the ducts in the truss space serve both units above and below?

Industry Standards

Question: 

I am currently putting together a set of truss specifications for a set of structural plans. I am interested to know of the most current publication that may specify industry standards in truss components (i.e. metal connector plates, wood quality and connection quality). Do you have any suggestions?

Decking On Bottom Chord

Question: 

Can I put a wood deck (1/2 in. plywood) on top of the bottom chord of a 26 foot span truss 24 inches on center?

Information On Frt Roof Trusses

Question: 

I need to obtain some information on fire-retardant-treated roof trusses.

Fire Cuts

Question: 

What type of construction uses a fire cut truss? Could you describe a fire cut truss?

Main Wind Force Resisting Systems Vs Components Cladding

Question: 

As an engineer, I have noticed truss designers in some high wind states routinely using “Main Wind-Force Resisting Systems” wind pressure coefficients as opposed to “Components and Cladding” coefficients to design for wind uplift. A roof truss is not a main wind-force resisting system and would have to have a tributary area of more than 1000 sq. ft. before qualifying for the lower Primary Frame coefficients. In my experience this practice is routine.