Commercial Roofing Construction Details: How to Flash A Pipe (CT-13)


For over a decade, I’ve been helping roofing professionals with low-slope roofing installations and inspections.

I spend a lot of time traveling throughout the United States, getting to know our customers, and instructing contractors through CertainTeed’s popular Flintlastic® SA Commercial Roofing Installation training courses. 

I’m also a member of the International Institute of Building Enclosure Consultants (IIBEC) and have attended more roofing training courses than I can count.

I tell you all this because I’m excited to share the knowledge I’ve gained in my years of experience through my new video series, Joe Knows

The series contains multiple episodes that will guide you and your team through the process of installing low-slope roofing using proven, manufacturer-approved application techniques. To kick off the series, I will demonstrate How To Flash A Pipe (Construction Detail CT-13).

Let’s Get Started!

Alright, now that you know a little bit more about me, let’s put our hard hats on and get to work. Flashing a pipe is an important detail containing steps that can often be overlooked. Properly flashing a pipe protects a building from leaks and water damage. To ensure correct application, please follow the provided instructions and watch my quick instructional video for further visual reference. 

1. To get started, position the base sheet and cut a hole to fit the pipe’s width

2. Once the base sheet is in place, Install a field-cut flashing collar using either the Flintlastic SA PlyBase base or flintlastic SA MidPly. Be sure the size reaches 4″  beyond the lead jack on all sides.

3. Next, round the edges of both the flashing collar and the lead. This will encapsulate the lead between the unpenetrated collar and cap, minimizing water incursion risk.

4. Now, set your lead in a 1/8th” bed of FlintBond SBS-Modified Adhesive, Caulk or Trowel Grade either to the back surface of the lead or onto the collar.

5. Apply FlintPrime Aerosol to the lead’s top surface and let that flash off for approximately 30 minutes, or until it’s tacky to the touch.

30 Minutes Later…

6. Now it’s time to install the Cap Sheet. Cut a hole in the cap to fit the pipe’s width, set the cap sheet in place, and remove the release film.

7. Once in place, roll out any entrapped air with a weighted roller.

8. Lastly, finish with a bead of flint bond caulk around the base and the pipe to seal off that interface.

Congratulations! You have successfully Flashed a Pipe. If you have any questions, you can submit via this form or leave a comment below. For additional information on CertainTeed products and installation, please visit, or go directly to our Flintlastic SA Installation Manual.

Happy Building, 


About Joe Thompson: A key member of the CertainTeed Commercial Roofing Technical Services team, Joe Thompson has been assisting customers with low-slope roofing installations and inspections for nearly two decades. Not one to sit on his hardhat, he travels throughout the United States serving as lead instructor for CertainTeed’s popular Flintlastic® SA commercial roofing installer-training courses. An IIBEC member in good standing, Joe has attended so many roofing educational courses that he has lost count.

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