There is no code specification for how far a metal roof panel should extend past the drip edge in the International Residential Code (IRC). But all codes require following manufacturer’s installation instructions, and the typical manufacturer’s spec is 1.5 to 2 inches. This overhang is necessary to prevent water from rolling around the edge and turning back across the bottom of the metal due to surface tension. 

    But on roofs with a gutter, a shorter 1.25 to 1.5 inches is recommended. This is because water rolls down the smooth surface of a metal roof panel much faster than the textured surface of an asphalt shingle roof. And, if the slope is fairly low and the metal overhangs too far, the stream of water produced in a heavy rain can overshoot the gutter. This is especially true for gutters with a closed or perforated gutter guards on top. The PBR metal roof shown below had a 3.5” panel overhang and stains on the outside face indicate a long-term problem with water going over the edge.

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Here’s links to some of our other articles about METAL ROOFS and RAIN GUTTERS:

• What is the difference between galvanized and galvalume metal roofing?

• What is the average lifespan of a metal (galvalume) roof?

• Should I put gutters on the house?

• Can metal roofing be used on a low slope/pitch roof? 

• What is the stuff you paint an old mobile home metal roof with to extend its life?

• Are rain gutters required by code?

• Does a house need gutters to pass inspection? 

• What do home inspectors look for when inspecting gutters?

 • Can I install a new metal roof over an asphalt shingle roof? 

• What color metal roof is best? 

• Why is my metal roof leaking? 

     Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.