# Ridge or Static Vents on Multi-level Hip Roof



## texasprd (May 14, 2011)

Any one? Please help me out with some advice and insight.

Thanks!


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## seeyou (Dec 12, 2008)

What type/how much inlet do you currently have? If that house was built with such inadequate outlet, the inlet situation needs to be examined.

I'm not a fan of venting hips and it's not necessary in your situation. Assuming the inlet is adequate and unobstructed, I'd vent the ridges and add turtle vents on the least visible hip planes. I'd also consider decorative venting, such as dormer vents and/or cupolas.


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## texasprd (May 14, 2011)

I don't recall the number with certainty, but it is either 32 or 36 8"x16" soffit vents. Judging by the NFA of the ones I see sold online or on mfgr sites, the inlet calculation seemed to be about adequate - fairly surprising given the exhaust situation.

When you say "venting hips", do you mean installing hip-ridge vents like these: http://www.airvent.com/professional/products/ridgeVents-hipridge.shtml If so, what is your objection?

Dormers/cupulos would be outside my budget (requiring an outside contractor - I wouldn't be comfortable doing that myself). What passive means, and location of same, would you recommend for venting the peaks/points over the garage (NE corner of house) and patio/bedroom (SE corner) ? I haven't worked out the area calculations for those two parts, but I suspect that I'd need more than one vent for each. If turtles, I was thinking about putting them on the east-facing and south-facing surfaces of those peaks, but I'm wondering about the dreaded "short circuit" effect - what do you think?


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## seeyou (Dec 12, 2008)

texasprd said:


> I don't recall the number with certainty, but it is either *32 or 36 8"x16" soffit vents.* Judging by the NFA of the ones I see sold online or on mfgr sites, the inlet calculation seemed to be about adequate - fairly surprising given the exhaust situation.
> 
> *When you say "venting hips", do you mean installing hip-ridge vents like these:* http://www.airvent.com/professional/products/ridgeVents-hipridge.shtml *If so, what is your objection?*
> 
> Dormers/cupulos would be outside my budget (requiring an outside contractor - I wouldn't be comfortable doing that myself). What passive means, and location of same, would you recommend for venting the peaks/points over the garage (NE corner of house) and patio/bedroom (SE corner) ? I haven't worked out the area calculations for those two parts, but I suspect that I'd need more than one vent for each. If turtles, I was thinking about putting them on the east-facing and south-facing surfaces of those peaks, but *I'm wondering about the dreaded "short circuit" effect *- what do you think?


Should be in the neighborhood of enough inlet if they are all functioning. Make sure there is no insulation blocking their flow and that they haven't been painted nearly shut.

Vented hips have potential to leak. Doesn't mean they will, but I envision added potential under extreme conditions. I have installed similar products when given limited options. I see them as a last option in your case. 

edit: if one was going to be worried about short circuiting, the hip vent would be a potential short circuit creating device.

I'm not too concerned about short circuiting. Even if it really occurs, heated moist air is still exhausted from the attic, maybe just not at peak performance. Air passing through the attic, even if it is for just a couple of feet, will mix somewhat with the attic air and/or pick up some of the heat. I suspect the only time short circuiting actually occurs is during strong wind events. I seldom see 25mph or stronger winds on 90 degree sunny days in my neck of the woods.

On placing the turtle vents: you might want to install a pyramid of 3 or 6 units closely spaced at the top of the hip planes you intend to vent. Or, there are other options (larger off ridge vents with greater NFA ratings) to use instead.


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## texasprd (May 14, 2011)

Thanks, SeeYou!

By "pyramid", do you suggest putting multiple turtles on the same hip plane? I was thinking about turtles at the same distance down from peak-point on adjacent/opposite planes.









I could replace the existing turbine vent between locations 1 & 2 with a turtle (costing some NFA), and add turtles in one or both adjacent locations (1 & 2) to take care of the larger peak. Locations 3-5 could take care of the smaller peak (though #5 would be used only if really needed since it would be visible from the front - I wouldn't use it if calculations show that locations 3 & 4 would provide enough area).


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## seeyou (Dec 12, 2008)

texasprd said:


> Thanks, SeeYou!
> 
> By "pyramid", *do you suggest putting multiple turtles on the same hip plane? *I was thinking about turtles at the same distance down from peak-point on adjacent/opposite planes.
> 
> ...



Yes - like this:


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## Ed the Roofer (Jan 27, 2007)

I would like to give this some deeper thought when I have more time tomorrow, but at first insight, I "Think" that I would recommend using multiple Solar Activated Power Vents.

Each different level of attic space must be closed off from the adjoining level per instructions though, so that each individual attic cavity could haver it's own Intake and Exhaust Ventilation.

Therefor, although you counted the amount of Total Soffit Intake Vents, you would need to individually calculate the NFVA per each level of attic space on it's own merits and make sure there are enough.

You can not go too much in regards to the Intake Ventilation Supply. I would rather have more than eenough, than Not Enough.

Ed


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## texasprd (May 14, 2011)

Thanks, Ed - I'll be interested to see what you come up with at "second glance". With solar-powered roof vents, how much of an issue would there be with residual heat/temps (either from heat absorbed in the roofing or ambient air/attic temps) after sun-down, when the fans stop? is it safe to assume that, if the fans are doing the job during the day, that there wouldn't be much heat stored in the shingles/decking? I'm thinking about the 100+ degree days we get here...

SeeYou, would you please list some names or links to the "larger off-ridge" vents you mentioned? I've come across one or two, but could use more instances.

Thanks, both of you!


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## seeyou (Dec 12, 2008)

texasprd said:


> Thanks, Ed - I'll be interested to see what you come up with at "second glance". * With solar-powered roof vents, how much of an issue would there be with residual heat/temps (either from heat absorbed in the roofing or ambient air/attic temps) after sun-down, when the fans stop?* is it safe to assume that, if the fans are doing the job during the day, that there wouldn't be much heat stored in the shingles/decking? I'm thinking about the 100+ degree days we get here...
> 
> SeeYou, would you please list some names or links to the "larger off-ridge" vents you mentioned? I've come across one or two, but could use more instances.
> 
> Thanks, both of you!



My experience consists of one personal home with power vents I could hear. After a sunny, 90 degree day, the fans usually ran 'til after midnight, at which time they would start turning on and off until they finally stayed off. All houses are not equal, but there was quite a bit of stored heat in that structure.

http://www.grantlogancopper.com/roof-vents


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## texasprd (May 14, 2011)

I've been up in my attic in the evening after a hot day - it's still quite warm in there. Since the fans (being solar powered) would stop running around sundown, wouldn't that greatly reduce the NFA of the fan openings - resulting in greatly reduced ventilation?

I understand it wouldn't be an issue with the fans running, but seems like it could be an issue after sundown. What about cloudy days, also?

Thanks for input!


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## texasprd (May 14, 2011)

I haven't decided for certain, but I'm leaning in the ridge vent/static vent direction. The original owners allowed the builder to get away with 3/8" roof sheathing - it might be 7/16, but I don't think so (since the builder used edge/joining clips, this appears to marginally within code according to my research). Since the sheathing is so thin, would I be wise to use screws to attach ridge vents? If so, what head-style? Triangular deck-/wood-style, or flat-head?


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## ratherbefishing (Jan 13, 2011)

I'm not a roofer, and don't play one on TV. But I just went through this on my house. I had lost a couple soffit inlets due to additions on the house. I had turtle vents on a hip roof, but the last roofer had punched 3" holes under 10" turtles. I had totally inadequate venting. In fact, when I cut off the rafter tails and soffit for my current addition project, heat poured down, out of the attic. That's gotta be a bad sign. 

With my new roof, I installed 4 of these: http://roofvents.com/roof-vent.html. I also installed 6 more 8x16 soffit vents. We haven't had a 100 degree day yet, but so far I'm impressed with the drop in temp in the attic. And no more hot air coming out of the soffit.


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## texasprd (May 14, 2011)

texasprd said:


> Since the sheathing is so thin, would I be wise to use screws to attach ridge vents? If so, what head-style? Triangular deck-/wood-style, or flat-head?


Hi, all - any thoughts on this question?

Thanks!


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## seeyou (Dec 12, 2008)

texasprd said:


> I haven't decided for certain, but I'm leaning in the ridge vent/static vent direction. The original owners allowed the builder to get away with 3/8" roof sheathing - *it might be 7/16, but I don't think so (since the builder used edge/joining clips, *this appears to marginally within code according to my research). *Since the sheathing is so thin, would I be wise to use screws to attach ridge vents? *If so, what head-style? Triangular deck-/wood-style, or flat-head?


If you use "shingle over" type ridge vent, then you'll still have to nail the ridge caps down. I wouldn't advise using the exposed aluminum ridge vent, if they even still sell that stuff.

7/16" and 1/2" plywood or OSB should be H clipped.


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## texasprd (May 14, 2011)

"since the builder used edge/joining clips" - it is H-clipped (not that I could do anything about it now, if it wasn't), thus marginally meeting code.

The ridge vent, if I go that route, will be shingle-over. But because the sheathing is so thin, what I've seen here & elsewhere indicates I might be wise to go with screws to actually attach the ridge vent because the thin sheathing doesn't give enough contact thickness with nails. So the question then becomes what style head (wood/deck/sheetrock-style, or pan-head) on the screws, so as not to cause problems with the ridge cap?


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## seeyou (Dec 12, 2008)

texasprd said:


> "since the builder used edge/joining clips" - it is H-clipped (not that I could do anything about it now, if it wasn't), thus marginally meeting code.
> 
> The ridge vent, if I go that route, will be shingle-over. But because the sheathing is so thin, what I've seen here & elsewhere indicates I might be wise to go with screws to actually attach the ridge vent because the thin sheathing doesn't give enough contact thickness with nails. So the question then becomes what style head (wood/deck/sheetrock-style, or pan-head) on the screws, so as not to cause problems with the ridge cap?


The shingle-over ridge vent that I'm familiar with just gets tacked down in place and then all the ridge cap nails penetrate the ridge vent and the sheathing. The ridge caps are not just attached to the ridge vent, so I can't see where screws would give any benefit. When tacking the vent in place, nail where the rafters/trusses are.


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