I recently gave a class on bracing of
metal-plate-connected roof trusses,
attended by about 50 structural engineers.
What I learned there about bracing
piggyback trusses literally left me
sleepless that night. In case you're not
familiar with the term, piggyback trusses
are used when the height of a required
roof truss exceeds the width limit
allowed by a state's transportation
department for transport on the back of
a truck. Depending on the state, the
limit is usually around 12 to 14 feet.
So say you need a 12/12 gable roof
truss for a 40-foot span. The 20-foot
ridge height will force the truss manufacturer
to provide the truss in two parts
— a bottom truss with a