When my now lovely bride (always lovely) first had me visit her home in South Dakota, I couldn’t help but notice her nicely sized 32 foot square stick framed garage. Like most stud framed buildings, it had light weight metal connector plated wood roof trusses manufactured from 2x4s. Like many garages, this one was unheated.
Having spent much of my adult life up until then in the truss industry, I could not help but look up at the trusses and notice things had gone to die between them…..chairs, tables, boxes, basically – stuff!
She was perfectly happy with the way her garage had performed and the roof had previously survived winters of extremely deep snowfall.
Wonderful – except the trusses were not designed to support a load on top of the bottom chords of this magnitude.
Certainly trussed roofs can be designed to support limited storage loads. The 2006 IRC (International Residential Code) Commentary provides the following:
- For attics with limited storage and constructed with trusses, this live load only need to be applied to those portions of the bottom chord where there are two or more adjacent trusses with the same web configuration capable of containing a rectangle 42 inches high or greater by 2 feet wide or greater, located within the plane of the truss. The rectangle shall fit between the top of the bottom chord and the bottom of any other truss member, provided that each of the following criteria is met:
- The attic area is accessible by a pull-down stairway or framed opening in accordance with Section 807.1; and
- The truss shall have a bottom chord pitch less than 2:12.
The storage load provision is for a non-storage (or dead) load value of 10 psf (pounds per square foot) and a storage load of 20 psf. These values can be found in the 2012 IRC Table R301.5 https://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_3_par037.htm?bu2=undefined
With reference specifically to footnotes b and g.
Considering a future desire to hide things in the attic space of your future pole (post frame) building? Then limited storage trusses may be an option well worth exploration!