Where there are multi level roofs or a tall parapet, you will need to flash the roof into the abutting construction. Extending the roofing, say EPDM, up more than 18"-24" invariably fails.
The detail below shows all the relevant issues. Although the sealant is a maintenance issue, it is easy to inspect and repair. Counterflashing built into the masonry requires less maintenance; but it is harder to determine if it needs maintenance; and it is harder to repair.
Anchoring the counterflashing to the surface of the abutting construction only works if the construction is basically smooth. Where the abutting construction is not smooth, consider providing a smooth panel for the counterflashing to attach to and then starting the other construction.
Also see our detail Roof Expansion Joint - New To Existing
- This detail is needed to specify the configuration, construction and materials required for the roofing counterflashing.
- This detail may require further details and specifications covering these conditions.
- You may want a specification covering the quality and installation aspects of these materials.
- These details should be placed on the Exterior Details sheet, the A-500 series of sheets per the National CAD Standards, contrary to the designation shown here.
- Download PDF of detail.