"Ice protection" defined

[Michael Thomas]

For the purposes of IRC 905.2.7.1 "Ice protection is required extending from the eave line 24” inside the exterior wall line", what constitute an appropriate underlayment?

Is this defined somewhere in the code, or do we fall back on the manufacturer's installation instructions?

[Jerry Peck]

For the purposes of IRC 905.2.7.1 "Ice protection is required extending from the eave line 24” inside the exterior wall line", what constitute an appropriate underlayment?


From the IRC: (underlining and bold are mine)
- R905.2.7.1 Ice barrier. In areas where there has been a history of ice forming along the eaves causing a backup of water as designated in Table R301.2(1), an ice barrier that consists of a least two layers of underlayment cemented together or of a self-adhering polymer modified bitumen sheet, shall be used in lieu of normal underlayment and extend from the lowest edges of all roof surfaces to a point at least 24 inches (610 mm) inside the exterior wall line of the building.
- - Exception: Detached accessory structures that contain no conditioned floor area.

[Michael Thomas]

Thanks for the quick response. I also found the attached.

[Ken Rowe]

an ice barrier that consists of a least two layers of underlayment cemented together


Just out of curiosity, has anybody ever seen two layers of underlayment cemented together?