Commercial Roofing Construction Detail: Base Flashing on a Parapet Wall (CT-06)


Hello Fellow Installers, 

Ready to learn another manufacturer-approved low-slope roofing installation detail? In this session I will coach you and your team through the process of Base Flashing on a Parapet Wall (Construction Detail CT-06). 

Proper waterproofing of a parapet wall, as with any transition, is critical in preventing potential roof leaks. It is important to remember that you can’t move forward with this installation detail without the cant strip. Installing a cant strip at the base of the parapet wall is a necessary step that will support the membrane at the transition while also acting as a shock absorber against structural movement. 

For successful installation, please follow the steps below, and then watch my quick demonstration video to see it in action. 

Let’s Get to Work! 

1. A proper base flashing detail starts in the field, so be sure to end your field membrane a minimum of 2” above the cant strip. 

2. On a maximum wall height of 24″, start your anchor or Flintlastic® SA NailBase turned over the outside edge of the wall by 2” and extend into the field 4”, overlapping any base flashing already in place by 4”.

3. Nail that off with standard metal cap nails, 4” on center on the outside edge, with a minimum of four fasteners in any laps, and 12” on center in the field of the wall.

4. When working with Flintlastic SA Self-Adhered Membranes, apply FlintBond® SBS-Modified Adhesive – Trowel or Caulk Grade – where the base flashing overlaps the granulated Flintlastic SA Cap sheet in the field to ensure a long-term bond. 

5. Your cap flashing ends at the top edge of the wall, and extends 2” beyond the base in the field. 

6. Even though the membrane is adhered, nail off the top edge using metal cap nails every 9” on center to prevent vertical slippage.

7. Again, where the cap overlaps the granulated surface in the field, apply FlintBond SBS-Modified Adhesive – Trowel or Caulk Grade. Note that this is not applicable to torch-applied systems.

8. Seal the top edge off with a bead of FlintBond Caulk. 

9. To prevent any granule contact with the underside of the metal, use  Flintlastic SA PlyBase or Flintlastic SA MidPly to install a field-cut, smooth-surfaced weatherproofing strip turned down 2” on both directions to cover any exposed metal fasteners.

Finally, install your FlintEdge® Coping per published application instructions.

Great work! You have learned the necessary steps for base flashing a parapet wall. 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

In the meantime, please be on the lookout for my next blog and video post detailing the installation method for base flashing the outside corner of a parapet wall (CT-10). If you missed it, check out my other installation blog posts:

 Commercial Roofing Construction Detail: Flashing A Pipe (CT-13)

Commercial Roofing Construction Detail: Flashing A Pipe With Liquid Applied Flashing (CTL-SF-06)

Commercial Roofing Construction Detail: Flashing A Drain (CT-12)

Commercial Roofing Construction Detail: Flashing A Drain With Liquid Flashing (CTL-SF-05)

Happy Building, 


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