Performance

Continuous Lateral Bracing

Question: 

How important is continuous lateral bracing in roof trusses? Is it detrimental to the roof integrity if it is missing?

Floor Trusses With Masonry Bearing Walls

Question: 

We would like to know if there is a problem with using wood floor trusses with masonry bearing walls without a ledger. Our local supplier has told me that encasing the wood truss in the masonry wall could be detrimental to the truss due to moisture. What, if any, suggestions do you have for this condition? If a bottom chord bearing is used, do the trusses need fire cuts? The two-story building contains masonry bearing walls with wood trusses on the second floor and wood trusses at the roof.

Attic Ventilation

Question: 

I need to put a new roof on my single-family dwelling. The house originally had gable and soffit/eave vents. The roofing contractor suggested that we install a ridge vent when new roof is installed. Should the existing gable vents be blocked off or does it not matter? I have read some debates about whether or not the combination of gable and ridge vents substantially reduces the effect of the soffit vents by having the intake now at the gable vents and exhaust at the ridge. Would this type of ventilation affect the truss warranty?

Health Hazards Of Mold On Lumber

Question: 

What are the health hazards of black fungus on Douglas-Fir lumber?

Life Expectancy Of Wood

Question: 

What is the life expectancy of wood that was used in an attic truss? Does fire retardant change the life expectancy?

Lumber Fatigue And Decay

Question: 

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?

Allowable Variances In Trusses

Question: 

My framers are always complaining that the “trusses are bad.” I am looking for tolerance information that not only addresses the allowable variance in length and height, but also allowable variation in the top chord with regard to straightness (i.e. how straight should a pull string line from the top and bottom of top chord be?). Also, if trusses are set on a perfectly level wall, what variation is allowed from truss to truss (i.e. if I put a 10 ft. straight edge perpendicular to the trusses, how much can they vary in height, not just at peak or bottom but all along the top chord)?

Truss Blow Down

Question: 

If trusses blew down from insufficient temporary bracing and the contractor put them back up without the knowledge of the truss manufacturer and gave the truss manufacturer a letter stating that the trusses were okay, is that sufficient? Do you know of any truss manufacturer who would accept this?

Installation Guidelines

Question: 

What are the requirements on the permanent bracing of bottom chords? Can gypsum board diaphragms be used?

Responsibility Of Snow Drift Load Calculations

Question: 

Is the truss designer or the building designer responsible for calculating snow drift loads on a roof system?