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I am having a difficult time figuring out the venting for my open air porch roofing project. This is new construction. I have a 4/12 pitch porch roof, 8ft wide, goes around 9 corners of my 2 story house, and has hips everywhere, 160 linear ft., 145 trusses and about 1400 sq ft of roof deck. It faces, North, West, and South covering 3 of the 4 sides of my square house. Roof shingles will be standard 30 year tar, 3 tab architectural in a darker (but not black) color. Titanium wrap + Ice and water shield underneath.

  1. Should I vent at all? So, this is western Montana. We get a lot of cold, and substantial wet all at once in the form of ice, snow and thunderstorms totaling about 14-16 inches a year. Overall it's fairly dry. I am in the lowest part of a river bottom valley and my place is often much more humid than others (above 80% for probably 50% of the year) due to fog settling etc. A lot of people don't know this, but we do get 90f+ degree temps for weeks or months at a time (up to maybe 110f on rare occasions for a few days). It's "Hot" from June to mid September. Rest of the year is cold < 50 degrees and down to negative -20s, -30s or colder.

  2. If I need to vent, I know how to do this in the soffit, but no clue on the roof deck since the trusses join to a wall of a 2 story house. There is no ridge area aside from 7 or 8 hips, but mostly these are all in one area going around a turret and on 2 ends. Most of the roof area has no hips in 3 of the main sections, for 30-40 ft. I have looked at a few products which seem to go underneath your "wall to roof" metal or replace it entirely. No one in my area sells them or is aware of them. No one in my area as far as suppliers seems to know what roofers are doin to vent in this instance. I suggested we use ridge vent (black, plastic mesh) underneath roof-to-wall metal and one supplier thought that sounded crazy and would look ugly. Possibly correct about that.

Is it typical to just not vent? Realistically, how bad is this?

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  • That’s a lot of area to not have some venting. With the heat build up in the summer if not vented that might make those walls warm. We built some homes on the east coast with similar porches around the home and we vented them and our climate was much milder only ~15 miles from the ocean. – Ed Beal Jan 21 at 22:26
  • @EdBeal Ya and it's interesting, i'm getting the impression contractors around here usually don't vent at all. If it matters, the siding is a bright white painted LP lap product. Interesting... these are the opinions i'd like to hear. But also, curious how you vented them as i'm at a bit of loss there. Do you think having the mesh ridge vent under roof-to-wall metal is a good idea or would look terrible? Planning integrated metal soffit vent underneath toward the outside edge of porch ceiling. – maplemale Jan 21 at 23:09
  • We used the ridge vent back when it was much thicker and at ground level it is not really noticeable, yes the vent Chanel’s under the soffits are but not really bad at all, we vented because without it the shingle warranty was void. I have seen other methods of vent lying that did not look as good (we used Chanel when we boxed soffits on all the homes we built, if not boxed just a spacer block with holes drilled and construction cloth stapled to it. What a brain fart I typed east coast and meant west coast homes. – Ed Beal Jan 22 at 0:46
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Various versions of a roof vent that comes up through the surface. There are several variations - this type has an internal part that comes up from the base sheet that is flashed in place over a hole, so that water does not get down inside despite having all those louvered openings.

Roof vent - image from Lowes

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  • ya i'm aware of turtle vents. But, frankly think they are ugly, out-dated and no one here uses them anymore unless it's on a cheap remodel / roof scrap and shingle. Anyway, no way these are going on the house. Would make a million dollar home look absolutely terrible. Especially since they aren't on the main roof which is a hip roof that is VERY visible everywhere. Think, victorian style large, hip roof, with massive wrap around porch. No way turtle vents will work. – maplemale Jan 21 at 23:14
  • Suit yourself. I've been massively underwhelmed by the actual performance of every continuous ridge vent I've met, plus you don't have much ridge anyway. Sometimes old fashioned stuff actually works. I'm going to have to retrofit a functional cupola on my workshop, given how poorly the CRV works there... – Ecnerwal Jan 21 at 23:22
  • Like many things, you can make anything look cool. Like, you can do copper or bronze turtle vents. But, i've never even seen one on a porch roof. Only on the main roof. My main roof has like 300 linear ft of hip that could just be ridge vented. I just can't believe the only option is don't vent, or use turtle vents or some crazy product someone patented and is trying to push like the integrated vent wall to roof metals which will take a month to get here to the tune of $1k – maplemale Jan 21 at 23:28
  • If it actually works, that thousand dollar product sounds like the idea solution to protect the "look" of your million dollar home. – Valkor Jan 22 at 9:15

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