Products

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).

This presentation provides an overview of fire-rated assemblies that include wood trusses. Topics covered include assembly testing, Harmathy’s rules, and an examination of fire performance in the field. 

Question: 

Is it common practice for the supplier/distributor of a truss to provide a publication regarding temporary bracing with the delivery of the material?

Question: 

Consider this statement from a set of construction contract documents: “The Truss Manufacturer is responsible for inspecting the truss installation, bracing, anchorage and bearings and preparing a letter of verification stating that trusses are installed and braced properly.” At first glance, it may seem that the truss manufacturer is the most logical party to perform such an inspection. They are the truss experts, are they not?

Question: 

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?

Question: 

I'm looking for a book that will provide formulas and design criteria for trusses. Can you give me any suggestions of where to find a book or fairly inexpensive software?

Question: 

How do you evaluate whether a metal plate connected truss is still usable after exposure to fire? Are there any recommended tests?

Question: 

I am looking for a company that can properly transport wood roof trusses on a one-time basis that are too large to fit into a box trailer. Trusses are to be fabricated in NC. Do you have any recommendations? Could be a specialty hauler or another truss fabricator in the area that has the special frame truss hauling trucks.

Question: 

I recall seeing a design recommendation several years ago regarding installation of hanger nails above the neutral axis of the bottom chord of a plated girder truss. The intent was to avoid dumping large loads into the bottom chord, below the neutral axis. Can you tell me where I can find this information?

Question: 

The Corps' guide spec for wood construction requires the drawings to indicate the design forces on each truss member for the worst loading condition. Loading conditions, of course, can include wind, snow build up, and unbalanced loading, to name a few. Many A/E firms submit drawings lacking these member forces, but instead show typical loading conditions. What does the wood truss fabricator want to see – truss diagrams with maximum loads on each member? Or would he prefer to design the truss from many required loading diagrams?