Frequently Asked Technical Questions
How important is continuous lateral bracing in roof trusses? Is it detrimental to the roof integrity if it is missing?
We have a customer that bought trusses in June. The trusses were shipped [ and one month later are] being set. The chords have weathered and bowed. What is the industry standard for dealing with this problem? What is our liability in this situation? We were not aware of any delays on the customer’s part and shipped as requested. Note: These trusses are 62 ft. scissor trusses.
I am currently undertaking a project dealing with techniques and methods of joining structural timber members. Do you have any available information on timber connections like split rings and design software?
The grading rules usually permit some percentage of visually graded lumber to be below grade – I believe it is 5%. ANSI/TPI 1 requires that all lumber used in trusses be of the grade specified by the truss design. A strict interpretation of ANSI/TPI 1 would require that the fabricator cull the 5% that is off grade. What are your thoughts on this?
Can one use pressure-treated lumber in metal plate connected truss construction? If so, are special plates or coatings required?
When webs are cut is it alright that sometimes the grade mark is removed? From a liability standpoint, what is the rule with grade marks and web members?
What is fatigue in lumber and how does long-term fatigue affect lumber? Does long-term fatigue cause cracks in lumber? What is the difference between long-term fatigue and decay? How do you determine whether lumber has been subject to long-term fatigue or decay?
In truss manufacturing, can hemlock, fir and spruce be used instead of Douglas Fir/Larch? What grades can be used: Structural Light Framing (Select Structural through #3) only, or Light Framing (Construction through Utility) as well?