Flashing and Penetration Details
EPDM pipe boot installation, inside and outside corner flashing, edge metal details, termination bars, and proper sealing techniques for all roof penetrations.
- Install pre-molded EPDM pipe boots with correct primer and splice tape application
- Fabricate inside and outside corner flashings using cured and uncured EPDM
- Detail edge metal terminations with proper membrane overlap and sealant placement
- Secure termination bars at correct spacing and apply caulk for a watertight seal
Lección 1
Pipe Boots and Round Penetrations
The Most Common Roof Penetration
Pipes - plumbing vents, conduit risers, gas lines, and mechanical exhaust stacks - are the most frequent penetrations through a commercial roof membrane. Each penetration is a potential leak point that must be flashed with care. EPDM systems use pre-molded pipe boots to flash round penetrations quickly and reliably.
Pre-Molded EPDM Pipe Boots
A pre-molded pipe boot is a factory-manufactured cone of cured EPDM rubber sized to fit over a specific pipe diameter range. Common sizes cover pipes from 1 inch to 12 inches in diameter. The boot has a flat flange base (typically 10-14 inches square) that bonds to the field membrane, and a tapered collar that wraps tightly around the pipe.
Installation Procedure
- Cut the field membrane in an X-pattern around the pipe. Fold the flaps up around the pipe and trim excess, leaving approximately 3 inches of membrane turned up against the pipe.
- Apply seam primer to the field membrane in the area where the boot flange will sit. Wait for the primer to dry (2-5 minutes).
- Apply splice tape in a square pattern around the pipe, sized to match the boot flange dimensions.
- Slide the pipe boot over the top of the pipe and press the flange firmly into the taped area. Roll the flange edges with a steel roller.
- Secure the collar to the pipe with a stainless steel worm-drive clamp. Tighten the clamp snugly but do not overtighten - the boot rubber should compress slightly under the clamp.
- Apply EPDM lap sealant around the top edge of the clamp where it meets the pipe to prevent water from tracking behind the boot.
Always Clamp and Seal
A pipe boot without a stainless steel clamp will eventually slip down the pipe due to thermal cycling and membrane shrinkage. Always install the clamp and seal the top edge with EPDM lap sealant - this detail is tested on the ProCertification exam.
Odd-Shaped and Multiple Penetrations
For square or rectangular penetrations (duct curbs, equipment supports), pre-molded boots are not available. These require field-fabricated flashings using uncured EPDM and splicing cement. For clusters of pipes close together, you may need to build a common curb around the group and flash it as a single rectangular penetration rather than attempting individual boots with insufficient spacing.
Pre-molded EPDM pipe boots must be primed, taped to the field membrane, and secured with a stainless steel clamp at the collar. Always apply lap sealant over the clamp to prevent water tracking.