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Community and Q&A

Ridge or roof vent for differing slopes

Kevin McGuire | Posted in General Questions on

I have a roof that is a 2:12 on one side and 4:12 on the other. Am I better off just using those mushroom style vents near the ridge, or an actual ridge vent?

im asking because I can’t find a ridge vent that accomadtes my roof with differing slopes on either side. They say the 2:12 is not steep enough or they don’t fit differing slopes, etc.

any recommendations here?

i currently have a standing seam roof, which has a minimum pitch requirement of 3:12 – so when I re-roof I am probably going to use normal shingles or something like it – if I can at 2:12…


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  1. Expert Member
    Malcolm Taylor | | #1


    I use two different suppliers of snap-lock metal roofing (Westman Steel and Westform Metals) Their panels and trim are almost identical, but one allows their use down to 3/12 and the other to 2/12 - so I wouldn't dismiss replacing your roof with a new metal one.

    I don't like applying either metal or shingles to a roof slope that low, but if I had to choose I'd prefer metal - and a metal cap can easily accommodate the two pitches.

  2. GBA Editor
    Martin Holladay | | #2

    One other factor to consider: a 2/12 roof is a low-slope roof, so the usual methods of providing a vent channel don't apply. For more information on low-slope roofs, see "Insulating Low-Slope Residential Roofs."

  3. GBA Editor
    Peter Yost | | #3

    Hi Kevin -

    Be surprised if any roof cladding or ridge vent manufacturer will warrant vent systems for less than 3:12 pitch; just too much potential for non-gravity directed bulk water movement (i.e. a leak or leaks). Also, at that pitch, just not clear how much actual air movement venting provides.


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