Lumber

Cottonwood Lumber In Truss Construction

Question: 

I am developing a sustainable community in southeast Iowa. We have an abundance of cottonwoods nearby. I plan to have them sawn into dimensional lumber on the site and dry it there as well. I would like to use this material for trusses. A truss plate manufacturer informed me that because he had no data for cottonwood, he was unable to design trusses using it. Can you offer any advice?

Fire Damaged Trusses

Question: 

I have been hired by an insurance company to determine the extent of damage to roof trusses exposed to fire. How much fire damage compromises the structural integrity of the truss?

Treated Lumber In Wood Trusses

Question: 

Can one use pressure-treated lumber in metal plate connected truss construction? If so, are special plates or coatings required?

Age Restriction On Lumber In Trusses

Question: 

I would like to know if there is an age restriction on wood trusses. How long after production are they safe to use? The trusses in question are at least three to four months old. Are they still safe to use? They have not been covered the entire time and are showing signs of age.

Post Fire Retardant Treatment

Question: 

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

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?

Visual Grading Criteria

Question: 

Where can I find a copy of the criteria used to visually grade lumber?

Finger Jointed Material

Question: 

Is finger-jointed material allowed in the manufacturing of trusses?

Two Hour Assembly Ul Number

Question: 

We have a local builder wishing to use floor trusses with a 2-hour assembly. I have shown him the 2-hour design on pages 17-27 of the second edition of SBCA’s Metal Plate Connected Wood Truss Handbook. Is this assembly UL approved? If so, what is the design number?

Lumber Grades In Wood Trusses

Question: 

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?