Floor Trusses

Open web trusses are the ideal match with a sprinkler system, maximizing use of space and making installation easy.

This research report will focus on manufacturer or trade association deflection requirements for a number of floor topping/covering related products where deflection requirements may impact serviceability.

Lumber Design Values

No matter the species, component manufacturers (CMs) purchase and rely on the accuracy and reliability of many different lumber design properties, including: bending (Fb); shear parallel to grain (Fv), compression perpendicular to grain (Fc^), compression parallel to grain (Fc), tension parallel to grain (Ft), and modulus of elasticity (E and Emin).

Would you please inform me of the specified requirements of the size and the amount of nail attachments from the truss to the top plate?

Is there a chart available on the allowable amount of deflection on floor trusses?

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

I am trying to develop a guideline for my firefighters regarding initial fire attack in buildings with light-weight trusses. My concern is truss failure, especially when exposed to fire. Is there any information on failure time related to flame impingement? Any information about truss failure – especially in a fire condition would be helpful.

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?

Are wood trusses designed to be fall protection anchors that would support a worker should he fall?

I have a four-year-old house with glued open-web trusses. Both the truss manufacturer and the builder have admitted to me that the trusses were installed wrong. I have a problem with the suggested repair. I have hired a structural engineer and he suggested installing a 2x10 between each truss and removing the old truss. This would have to take place on both the first and second floors because all the trusses were installed wrong. The manufacturers want to install six strongbacks on each floor, hoping this will tighten them up.