26 September 2006
Perimeter, Parapet, and other Miscellaneous Flashings.
Utilize the same factory finished material as roof panels for exposed flashings and
shrouds. Provide slope for all parapet and coping caps and all horizontal projections of
OTHER ROOFTOP APPURTENANCES.
Minimize other roof accessories that penetrate the roof panels. When painted products
are used, every effort should be made to use the same sheet material as the roof,
incorporating the same factory finish.
Provide snow guards for any project where sliding ice and snow may pose a hazard or
nuisance. Select snow guards to resist all in-service loads considering roof slope and
design snow load. Prove adequacy on a site-specific basis by calculation and lab-
tested holding strengths of devices. Only non-corrosive metal seam clamping (non-
penetrating) type snow guards may be used. Snow guards that glue to panel surfaces
or use attachments that penetrate roof panels are prohibited. Any device that voids
material and coating warranties must be avoided, such as attachments that penetrate
the standing seam or scar the surface such as concave set screws.
Use aluminum lightning protection on metal roofs where appropriate. For locations
where the average snowfall exceeds 100 mm (4 in.), snow guards must be used in
conjunction with lightning protection.
Dormers, Equipment Screens, and other Mountings.
When possible, avoid interrupting roof planes with dormers and other geometries that
impede drainage or interrupt the drainage surface. Dormers and equipment screens
that are used for ornamentation, or to conceal vents or other small mechanicals, must
be attached to the seams with non-penetrating seam clamps--avoiding breach of the
weathering surface. Attach other appurtenances (lightning arrestors, condensate lines,
conduits, roof walks, satellite dishes, etc.) with non-penetrating seam clamps. Avoid the
use of dissimilar metals. Jacket any copper lines to isolate and prevent copper ion
Determine roof pressures and pressure zones in accordance with ASCE-7, Minimum
Design Loads for Buildings and Other Structures. Show zone sizes, design pressures,
and clip spacing on the plans. Prove panel capacities by ASTM E1592 testing to resist
pressures as shown on plans for each zone.