# Hip Ridge Vents?



## markstg (Nov 28, 2010)

Hello,

Sure could use some feedback on the ventilation of an attic for a house I'm building. Attic is 3700 square feet, using 1 square inch/150 Square Feet Net Free Area and then splitting that 50/50 between intake and exhaust ventilation, I need 1776 square inches of exhaust ventilation.

Roof has 50 linear feet of horizontal ridge that I plan on using Air Vent Inc's Shingle Vent II ridge vent. This ridge vent has 18 square inch Net Free Area per linear foot ventilation which means I need 100 linear feet of ridge vent of which I only have 50 feet, or 900 square inches of the required 1776 needed. To get the the additional exhaust ventilation I would like to use Air Vent Inc's hip ridge vent which gives 12 square inches of Net Free Area per linear foot, to get the 73 feet of hip ridge vent needed for the remaining exhaust ventilation.

My architect says all hip ridge vents will allow water into the attic. Does anyone think this is true? I don't want to use power ventilation. All comments welcome. Thanks


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## greg24k (May 19, 2007)

Never had a water issue with a ridge vent...been using them forever. Just make sure it's installed right.


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## kage (Aug 17, 2008)

have not had a problem with hip vents.


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## Jason-F (Jul 4, 2009)

I have never seen installed it hips and don't intend to, in driving rain there likely would be a issue.

If you install 50 Ft it will be within spec recommendations. You would be within the minimum of 300/1. If you wanted more add a couple free standing roof louvers to increase your exahust vent area.


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## markstg (Nov 28, 2010)

Jason-F said:


> I have never seen installed it hips and don't intend to, in driving rain there likely would be a issue.
> 
> If you install 50 Ft it will be within spec recommendations. You would be within the minimum of 300/1. If you wanted more add a couple free standing roof louvers to increase your exahust vent area.


 
My understanding is you can go with 300/1 if the attic insulation has a vapor barrier, which I do not plan on having.

I live in South Louisiana so snow and ice are not a concern, but it does rain hard which is my concern with hip ridge vents.


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## Jason-F (Jul 4, 2009)

No, I don't believe it has anything to do with vapor barrier. Roof's with a pitch under 4/12 required the 1/150 venting but if your roof is over 4/12 you will be fine with 1/300. Code around here is 1/300. We go by 1/300 for pretty much everything. If i was you I would go with the 50 ft of ridge vent and a couple roof louvers, say 5 you would have around 1150 NFA of exhaust and do the same for the intake. It will be good to go.


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## DFW Roofing (Mar 4, 2011)

300/1 is most common.

I was at a training given by Air Vent and they strongly recommended that you do not mix and match different ventilation products. If you use ridge vent, only use ridge vent etc. The problem when mixing and matching is one vent is always more efficient than the other. One may become an intake and create a "short cycle" where and exhaust vent becomes an intake.

That said, Air Vent would not recommend louver vents and ridge vents.


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## Ed the Roofer (Dec 12, 2006)

You are correct about the vapor barrier.

I have successfully used Shingle Vent II as the Ridge Vent product and prior to Air Vent promoting their version of a Hip Vent, I properly used the Trim-line Vent or Vent Sure Vent on the hips.

The hip roofs that I did this on had rotted the previous shingles in 8 years due to a lack of ventilation.

Also, they were both Vaulted/Cathedral Ceiling styles on the interior, plus I also installed continuous Insulation Baffle Vents from the eaves the the hips.

I also installed proper Intake Ventilation utilizing the Smart Vent Intake Vents along the entire eave perimeter.

Those were both about 4 years ago and are still functioning properly today.

Ed



P.S. I have photos available next time I am at my office with some spare time to be able to post.



.


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## Stephen H (Feb 18, 2011)

DFW Roofing said:


> 300/1 is most common.
> 
> I was at a training given by Air Vent and they strongly recommended that you do not mix and match different ventilation products. If you use ridge vent, only use ridge vent etc. The problem when mixing and matching is one vent is always more efficient than the other. One may become an intake and create a "short cycle" where and exhaust vent becomes an intake.
> 
> That said, Air Vent would not recommend louver vents and ridge vents.


 I was at an AirVent seminar this Tuesday-and they were quite adamant about NOT using a ridge vent in conjunction with slant back vents--- and also quite adamant about NOT using a gable vent with a ridge vent.

while I might very well use the hip vents at some point- I am not,as of yet, willing to experiment with "The Edge" vent they are currently pushing-as it looks like a leak waiting to happen to me.
stephen


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## Ed the Roofer (Dec 12, 2006)

Photo of roof section with Hip Vent.












This photo was taken 4 years ago, which was about 1 year after we finished the project.

There is Smart Vent on the entire eave and Hip Vent on both entire hips. Also, the Rafter Bay Insulation Baffle Vents are continuous from the eave to the hip intersection.

Ed


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## bender_dundat (Feb 20, 2011)

My understanding of ventilation is that you want your ventilation at the highest level and that you don't want ventilation of the same attic space to occur at different levels. I don't believe the issue is mixing the type of ventilation but that in mixing the type (ridge vent, lo pro), you inevitably have it at different elevations. Same reasoning for closing off a gable vent if ridge vent is installed.

With that said, I cannot understand how hip vents work as this obviously violates this "golden rule" for ventilation of roofs.


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## Tinstaafl (Jan 6, 2008)

Ed the Roofer said:


> Photo of roof section with Hip Vent.


Ed, that image doesn't show. You have to be logged into JLC.


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## jmiller (May 14, 2010)

bender_dundat said:


> With that said, I cannot understand how hip vents work as this obviously violates this "golden rule" for ventilation of roofs.


Hip roof, cathedral ceiling underneath- continuous soffit vent, continuous baffles every bay... (what Ed said)

We had an architect spec that on his own house a couple years ago. Made sense to me, though I'd have just went with CC foam.


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## Grumpy (Oct 8, 2003)

I don't like hip vents, won't install them. I can't see how they wouldn't let in a driving rain in a 40 mph wind. 

I also don't like on the roof intake vents like the edge vent or smart vent, though I have installed the edge vent last year. We just went through a near record breaking winter and they performed well so my mind is being slowly swayed. I prefer behind the gutter vents like the inhaler or just building out a false fascia.


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## Ed the Roofer (Dec 12, 2006)

Tinstaafl said:


> Ed, that image doesn't show. You have to be logged into JLC.



It showed up when i did the Preview Post.

I'm glad you found out where I plucked it from.

Ed


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