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).

Our home caught fire last month and burned partly through a tongue and groove ceiling to the trusses. Some are charred. Our contractor did a moisture meter test. An engineer for the insurance company said the trusses were only smoke damaged & the moisture meter test is invalid (it can be set to read anything). I found one article on charred trusses, but it’s pretty vague. We do not feel safe with the insurance engineer’s assessment because some of the trusses are obviously charred. We hired an engineer who agreed with us.

I am looking for some information regarding black surface mold on lumber. Does it alter the integrity of the lumber stress values? I have a client who wants to use “all dry” lumber for his construction but I do not know if this is really necessary.

The industry suggests notching the gable end truss to support the overhang. Is this wise? What about a structural gable, or a gable designed with drag loads, or one with only partial bearing? How safe is it for a framer working with a truss that has the top chord cut repeatedly?