Design

Standard On Center Spacing

Question: 

What is the recommended standard spacing for open-web wood joists? I have seen them placed 24 in. O.C. Is this acceptable for a customer who will have an exercise room with 500 pounds of free weights? I understand there are problems with bouncy floors with 24 in. spacing. Is this true?

Anti Trust Agreements

Question: 

I am looking for a set of guidelines or “rules” for members of the SBCA. Are truss plants really not allowed to speak of business matters? I think that is unfair. I'm not going to call up our competitor and tell them that they aren't charging enough and taking all the business. I just want all the truss plants in my area to get together and decide how we are going to do business. We need to standardize the industry.

Truss Design

Question: 

Recently, I was invited to view a newly-constructed 60 ft. by 36 ft. barn, with homemade big timber trusses as follows: 36 ft. span, 12/9 pitch, construction was 26 ft. 2x12 rafters, bracing 2x6, ceiling joists were 36 ft. boxed, 6x12 out of overlapping (6 ft.), 2x12 glued and nailed center, 16 feet of joist doubled as an 8 ft. high loft, floor trusses were on 12 ft. centers atop posts deeply anchored with good footings, roof and wall cross ties were 2x6 on edge every 24 in., floor cross ties in the loft were 2x8 on edge every 16 in., 4 ft. snow load.

Truss Repairability

Question: 

Occasionally we deal with truss failures due to impact and or crushing forces such as trees falling onto roof structures. At what point can the truss no longer be repaired? Also, what should an adjuster look for when determining repair-ability? Or should a storm adjuster basically punt and call a consultant for every truss failure?

Bracing Schematics

Question: 

Are there any schematics available on how to horizontally brace a 7/12 pitch roof?

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?

Fire Rating For Truss Assemblies Built With 2x3 Lumber

Question: 

Are there any published studies or guidelines on the fire rating of floor trusses built with 2x3 lumber?

Owner Assurance

Question: 

As the owner for a building designed to have metal plate wood trusses, what documentation should I receive to be assured that the manufactured wood trusses delivered to the site have indeed been manufactured at a licensed and registered wood truss manufacturer under the required written quality control procedures?

Jack Truss Connections To Girder

Question: 

In a hip roof application where jack trusses connect to a girder truss using pressure blocking (power blocking), what is the proper installation and the span that is acceptable before a hanger is required?

Floor Truss Span Tables

Question: 

Do you have open web floor truss span tables available?