Low slope residential roof vent question
Climate zone 7, lots of snow (high rockies)
Is it worth venting over the top of the sheathing to prevent ice damming on a 60′ long metal roof with a pitch of .75″/12″ ?
I am not talking about the “attic venting”.
The assembly, as it currently stands, inside to out:
2_11 7/8″ TJI perpendicular to long low slope w/ R-55 closed cell spray foam.
3_1/2″ Foam thermal break between sheathing and TJI upper flange.
7_Floating metal roof (for thermal expansion)
An alternate roof material I am considering is a ballasted torch down roof, but the owners are somewhat averse to this. SO, with the metal roof, can anyone weigh in on the effectiveness of venting? I am considering a product called “Delta Trela” which is a dimpleboard vent product that goes under the metal roof. Questions? Comments? Suggestions?
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