Roof Trusses

Lay-On Gables are an opportunity for component manufacturers.

An unusual project with an uncommon shape presented the kind of design challenge truss technicians don’t see every day.
 

When Jim’s Apple Barn, the largest candy store in Minnesota, wanted to expand by way of adding a confection-filled planetarium to the end of a blazing yellow barn already bursting with sweets, it had a difficult time finding a truss company willing to take on the project. “We were the only ones that said yes,” recalled Trevor Ebinger, a member of the Manion Lumber & Truss sales staff. “It was quite an undertaking.”

A little forethought can prevent the potential overstress that occurs when deflection leads to rooftop ponding.

The BFS design team in Shelby, Alabama “collaborate on anything that doesn’t sit right,” says Thom Patton. One result: a roof that rests perfectly on a school building after a simplified build and easy install process.

This Research Report will look specifically at the sill plate requirements according to the 2009, 2012, and 2015 International Residential Code (IRC) and International Building Code (IBC) and clarify if a sill plate is required in the following conditions:

  • Flat truss bottom chord bearing on ICF wall.
  • Flat truss top chord bearing on ICF wall.
  • Roof truss bearing on ICF wall.

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).

What does KD-HT mean?

Occasionally we deal with truss failures due to impact and or crushing forces such as trees falling onto roof structures. At what point can the truss no longer be repaired? Also, what should an adjuster look for when determining repair-ability? Or should a storm adjuster basically punt and call a consultant for every truss failure?

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