Eaves, rakes and drip edge · Lesson 2 of 4

Eaves, rakes and drip edge: materials, standards and design constraints

The 2018 IRC minimums, editions and amendments, fastening and overhang rules by maker, edge metals, high-wind programmes, ice barriers, metal-panel and membrane-roof edges, and the AFS limits that shape a custom drip edge.

You will be able to: State the 2018 IRC drip edge minimums and why the edition matters, layer the shingle maker and any high-wind programme on top, pick an edge metal, and apply the AFS limits to an edge profile.

15 min · 12 slides · 13 questions

All lessons in this module

Slide 1 of 12

The code minimums

The 2018 IRC (R905.2.8.5, as published by Pacific, Missouri) asks:

Adjacent pieces overlap at least 2 in
It extends at least 1/4 in below the roof sheathing
It extends back onto the roof deck at least 2 in
Fasteners at no more than 12 in on center

Sources

2018 International Residential Code, Chapter 9 Roof Assemblies (as published by the City of Pacific, Missouri) - City of Pacific, Missouri

Videos for this lesson

What this video shows: Union, a panel maker, installs box rake trim on its Advantage-Lok II standing seam panel; the description notes hemming the rake edge as an alternative. One maker's method for its own panel.

Video: How to Install Standing Seam Metal Roofing - Box Rake Trim. by UnionCorrugating, on YouTube. AFS checked its description against this lesson.

What this video shows: Union, a panel maker, installs eave trim with its Advantage-Lok II snap lock panel. One maker's method for its own panel, not shingle drip edge.

Video: How to Install Standing Seam Metal Roofing - Eave Trim. by UnionCorrugating, on YouTube. AFS checked its description against this lesson.

Glossary

R905.2.8.5: The IRC section that sets the drip edge rules for shingle roofs; the values in this module are from its 2018 edition.
Amendment: A local change to the model code, such as South Carolina requiring drip edge only where the manufacturer requires it.
Shingle overhang: How far the shingle edge projects past the drip edge. ARMA and NRCA give 1/4 to 3/4 in past an L profile; a shingle maker's instructions may set the window for its own shingles.
Ice barrier: Where the local climate table calls for one, two layers of underlayment cemented together or a self-adhering polymer-modified bitumen sheet, run from the lowest roof edge to at least 24 in inside the exterior wall line, and on roofs of 8:12 or steeper also at least 36 in along the roof slope from the eave edge. That is the R905.1.2 text Hilltown Township, PA, publishes under the heading 2015 IRC; confirm the edition your jurisdiction has adopted.
Splice plate: A short plate under the gap between two lengths of a membrane-roof drip edge.
Girth: The flat width of the blank: all legs to the mold line plus hem allowances. AFS limits it to 48 in.