Ice Barriers Explained: Do You Need Them or Not?
An IRC table lists whether or not an ice barrier is required, but not all roofing requires an ice barrier, even in ice-dam territory
Ice-dam leak-protection membrane is required along the eaves of roofs in parts of the United States where ice dams have a history of forming. You probably already know if you live and work in an area where ice dams occur, but you can verify whether an ice barrier is required by checking the local building code. Table R301.2(1) in your code jurisdiction’s version of the International Residential Code (IRC) lists Climatic and Geographical Design Criteria.
In the block toward the upper right side of the table is listed “Ice Barrier Underlayment Required.” Under the title your code jurisdiction should have filled in “Yes” or “No.”
Section R905.1.2 Ice Barriers (2018 IRC) outlines which roofing types require ice dam leak protection, what materials can be used as an ice barrier, and how far up the roof plane the barrier must be installed.
Not all roofing materials require an ice barrier. Roofing materials that do require an ice barrier are: “asphalt shingles, metal roof shingles, mineral surfaced roll roofing, slate and slate-type shingles, wood shingles and wood shakes.” Though not called out in R905.1.2, PV roof shingles and building-integrated PV roof panels do require an ice barrier, and that is noted under the subsections for those materials.
I find it’s interesting that concrete and clay tile roofs don’t require an ice barrier.
Metal roof panels, built-up roofing, and single-ply roofing membranes also don’t require ice barriers. And the code doesn’t specifically list specialty manufactured roofing products like stone-coated steel and plastic roofing panels. Most of those products will have an ICC-Evaluation Service Report that will either list the requirement for an ice barrier or refer to the installation instructions. I checked a few products, and those that are lap-style individual shingles or overlapping panels require an ice barrier and often note following the building code requirement for ice barriers.
Check out the other parts of this series on ice barriers:
- Ice Barriers Explained: How Far Up the Roof Slope?
- Ice Barriers Explained: What Materials Can You Use?
These articles and podcast episodes shed more light on the topic:
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