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IRC question regarding drip edge flashing

kbentley57 | Posted in Building Code Questions on

I was discussing flashing thickness requirements with a few friends over lunch (riveting, I know), and I’d like y’all’s opinion. 

Most other flashing requirements are called out by minimum thicknesses, typically 0.5 mm or 26 gauge, like in sections R905.2.8.x. 

However, the section about drip edge flashing only calles out requirements on the length of the flanges, but has no requirements about the thickness of the material. This has essentially led to the situation where your choices are 29 gauge, or some sort of pvc. 

Obviously you could have someone bend up whatever material you wanted, but really all that means is that if you’re buying “off the shelf” from the lumber yard or the big box store (around here), 29 gauge is all you get. 

should the code call out a minimum thickness here to stay in line with the other parts?  Is 29 gauge really ok and I’m just being a flashing snob?  Did I completely miss the code section that calls it out, and this question is pointless?  

Happy Friday!

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  1. Expert Member


    I don't have any answers as to what your code wants, but yes 29 ga flashing is junk.

  2. gusfhb | | #2

    Try a commercial roofing supply[ABC Supply for example] or a real old school lumberyard
    When I bought shingles for the roof in my current house, they sold lifetime shingles that were a completely different product than the same brand lifetime shingles at the big box stores.

  3. Expert Member
    Michael Maines | | #3

    I imagine the reason is that most flashing is the first line of defense, and sometimes (more often than it should be) it's the only line of defense against stormwater infiltration. Metal drip edges aren't even really necessary; I've seen and built many roofs with wood shingles for the eave flashing and no dripedge at all along the rakes, though I wouldn't choose those methods today. But drip edges are pretty well protected from the elements and very rarely rust through, so 29 gauge seems to be good enough for most people. I prefer a thicker gauge and like gusfhb, have found that roofing suppliers and even many lumberyards carry thicker gauges than big-box stores.

    1. Expert Member
      MALCOLM TAYLOR | | #4

      True, but drip edges are also one of the few profiles of flashing that rely on the rigidity of their material to keep their shape. It's important that it is made of a thick enough gauge to stay straight over time.

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