Number Two - "DON'T"
Complicated construction of hat channel vertical valley blocking and cross
stringers result in excessive height build-up, multiple pieces and a rigid
connection that does not allow for thermal forces*.
NOTE that thermal expansion/contraction of new thru fastened roof panel
results in trauma at the fixed fastener points - shear and "backing out" of
fasteners as observed in field inspections.
Design requires two fasteners each at blocking and stringer plus valley of
new sheet for meeting wind load code. 5-6 fasteners per foot equals high labor
costs for an inferior job.
This system should only be used with standing seam re-roof panels mounted
on clips which allow for thermal movement forces.
