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Vent under metal roofing

2415 Views 6 Replies 7 Participants Last post by  mako1
Hi all,

I'm going to give a friend a hand putting metal roofing over an existing roof (rolled asphalt - 3/12 pitch). There are no soffit vents (no soffits on the house), just two gable vents.

I was thinking about how to add some ventilation. My thought was to cut a strip vent (2" wide) in the existing roof deck (two feet up above the gutters) along the length if the house, then cover with screen, or cobra vent material. Then lay wood purlins and attach the metal roofing.

I was also going to seal the gable vents and add a ridge vent.

Does this sound like a decent plan?

Thanks for the advice
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Are there possibilities of ice dams?

Generally, you'd look to have at least 1 sqft ventilation for 300 sq ft of attic Keep in mind, the 2" wide strip is going to have something like 1-1 1/2" effective ventilation width once the screen is put in.
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