Design

One Hour Roof Ceiling Assembly

Question: 

I am looking for a 1-hour roof/ceiling assembly for wood truss construction. I would like to apply the drywall directly to the bottom of the truss and also have insulation for sound control. Is this possible without using channels and what UL number would I use?

Sprinkler Loading

Question: 

Does the NFPA sprinkler standard address sprinkler loading? If so, how and where do I buy it? What other information do you have on sprinkler loading? How do other truss companies price jobs for sprinkler loading the plans do not include a sprinkler layout or even say what size/type of sprinkler system will be used?

Alternate Nailing Patterns

Question: 

Some truss lumber repair nailing patterns call for 16d common nails. Most nail guns do not support 16d nails, but have an equivalent to a 12/10d nail. Is there a substitution guide or ESR report that could help us?

Wood Three Hour Fire Assembly

Question: 

Is it possible to construct an assembly for ceiling between first and second floors using 2x with few layers of gypsum to obtain a 3-hour fire rating?

Warning Poster Caution Notes

Question: 

We are concerned with SBCA’s BCSI-B1 Summary Sheet which under “Notes” makes a disclaimer. Our concern is if there would be an accident with our trusses and we point out that the bracing was not placed correctly according to SBCA documentation, which is sent with every job. If the accident goes to court, how will our attorney respond when the opposing attorney points out the disclaimer, which infers that the bracing we recommend must be flawed, otherwise it would not be disclaimed?

Substituting Fire Rated Wood Truss Assemblies For Light Gauge Steel

Question: 

We recently received bids on a school project, which referenced UL P523. This assembly used light-gauge steel trusses. We noted on the drawing that we could accept an alternate design using wood trusses in lieu of light-gauge steel framing, if the alternate design could meet the fire ratings.

Design Loads Vs Typical Loading Conditions

Question: 

The Corps' guide spec for wood construction requires the drawings to indicate the design forces on each truss member for the worst loading condition. Loading conditions, of course, can include wind, snow build up, and unbalanced loading, to name a few. Many A/E firms submit drawings lacking these member forces, but instead show typical loading conditions. What does the wood truss fabricator want to see – truss diagrams with maximum loads on each member? Or would he prefer to design the truss from many required loading diagrams?

Truss Bracing At Supports

Question: 

I almost always see wood trusses erected with no stability bracing at points of support. It seems to me that common sense and section 3.3.3.4 of The American Wood Council’s National Design Specification for Wood Construction (NDS) require that lateral support be provided at points of bearing. Plywood decking doesn't provide any more restraint for a wood truss than it does for a roof joist. I doubt if it was a concern with short span trusses having 4 in.

Storage Loading

Question: 

How much weight can a wood truss hold, when it’s made with 2x4 material and spans 36 ft. with a 4/12 pitch. I would like to hang things from the ceiling and am wondering if it is safe. I live in an area where there are heavy snowstorms. Also, how much exposure to the weather can a truss handle before there is a problem?

T-bracing

Question: 

The truss industry maintains that the design of truss roof and floor system permanent bracing is the responsibility of the building designer. System permanent bracing covers the entire structure and all bracing element interactions.