Performance

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?

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.

Gable End Bracing

Question: 

Some building designers believe that gable end webs need to be L-braced to 90% of the web length, which sounds fine. However, they spec that scissors gable end webs need to be braced to 100% of the web length. That means that in the field they are notching the braces to fit around top and bottom chords – you can imagine how difficult that can be. Is that necessary or even the intent of the web L-bracing?

Partition Separation Lag Bolting

Question: 

Is lag bolting the bottom chord of a truss to the top plate of a wall a proper fix to correct truss arching, assuming the attic is properly vented?

Post Fire Retardant Treatment

Question: 

Is a Class A fire rating (provided by our liquid spray-on fire retardant) acceptable in certain situations?

Installing Valley Sets

Question: 

What are the requirements for installing “valley set” overlay roof trusses? I am interested in nailing and support conditions. Some engineers ask for the bottom chord of the valley truss to be ripped to match the roof pitch of the underlying trusses. Is this necessary?

Roof Truss Nailing With Hurricane Clips

Question: 

If you use hurricane clips to secure roof trusses from uplift, are you allowed to use fewer than the typical three nails in the bearing heel of the roof truss? I am concerned because we want to do the right fastening schedule, but three nails in addition to the hurricane clip splits the wood. What is the standard recommendation?

One Hour Fire Rated Assemblies

Question: 

The Gypsum Association “Fire Resistance Design Manual” (GA-600-12) lists file RC2601 with two layers of 5/8 in. gypsum wallboard (GWB) on wood joists.

Installation Guidelines

Question: 

Are there any associations that have recommendations for the installation of wood trusses?

Truss Design Factors Of Safety

Question: 

I am currently working on a project where a wood truss system was loaded with a heavy spring snow. I do not believe the load was beyond the truss's design capacity, but how do you know? Is there safety built into wood trusses? If the trusses were loaded beyond their design capacity, it would not have been for a long duration.