This detail illustrates the installation of sag straps on roof purlins for a gabled roof configuration. Sag straps prevent purlins from rotating or deflecting under load and help maintain proper purlin alignment.
Sag straps (BANDSW) are 2" x 24 gauge steel straps installed on the bottom of purlins only. Each strap is secured using (2) Phillips pancake head screws at each purlin connection. The straps run diagonally between purlins in an alternating pattern.
X-sag straps are installed at a maximum of every 5 purlin spaces from the low eave only. At the ridge, X-sag straps are standard. Note that maximum purlin spacing is 5'-0"
