# attic ventilation design help



## Ed the Roofer (Jan 27, 2007)

I will answer inside your quote for you, one topic at a time.

Ed



Noreaster said:


> I'm still early in the learning curve and would appreciate any help with a bunch of questions .
> 
> Now for the house specifics:
> 
> ...


Ed


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## Noreaster (Apr 27, 2008)

Thanks, Ed.

Do you foresee a problem using an In-Vent or SmartVent at the dripedge of the roof overhanging the kneewall on the front of Gambrel roof house? There is no gutter here.

It faces northeast and catches a lot of wind and snow during some winter storms but being a Gambrel roof, you are basically looking at/seeing the roof constantly and I would only want to put it 3' up from the edge if it were necessary.

Since the back of the house has a gutter running full length (and no soffit), would you install the Smartvent at the dripedge over the gutter or 3' up the roof?

Thanks again.

Peace of mind is beginning to creep in


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## Ed the Roofer (Jan 27, 2007)

A photo might help or a drawing showing where the knee wall is located.

How substantial are the winds and snows you are referring to?

Ed


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## Noreaster (Apr 27, 2008)

Ed:

My camera takes film  Although it doesn't have a full shed dormer across the back, this jpeg http://z.about.com/d/architecture/1/0/E/2/1864-5.jpg shows a situation similar to mine on the front. I also have two gable dormers like those shown.

As you look at the front of a Gambrel cape, from the top of the kneewall down to the gutter, although it has roofing shingles on it, doesn't have attic space behind it---it is a crawlspace accessible from the bedrooms behind. 

From the top of the kneewall up to the ridge is all attic space. This is where I wanted to install an IN vent, SmartVent or Edge as an intake vent---the dripedge at the top of the kneewall, just above that piece of trim.

There is no gutter at this location---just a dripedge that hangs over a piece of trim that runs the full length of the front of the house. Although I've seen globs of ice hanging from the gutter at the foot of the kneewall, I've never seen them hanging from the overhang at the top of the kneewall. However, my attic has always been cold due to the oversized gable vents for the whole house fan. Those vents are going away though.

I've seen pictures on one of these forums of Smartvent installed directly behind a gutter with ice hanging from it and evidently no problems. Their roof slot is 6" above the dripedge.

I spoke with someone technical at Cor-a-vent who says to mount IN-vent 36" up from dripedge. This isn't a problem on the back of the house as you really can't see it. On the front of the house, due to the Gambrel roofline, it will be obvious as a 34' stripe across the roof.

At AirVent, someone is supposed to get back to me assuring me that I can mount the Edge at the dripedge on the front of the house.

I guess I want it all :wink: I want Shinglevent II on the ridge, IN-vent on the back roof, 36" from the gutter (for peace of mind) and the Edge or Smartvent over the trim at the kneewall. With a black roof going on, the black Edge would be less conspicuous.

In your installations of Smartvent, do you put it right up to the dripedge despite being above a gutter or do you pull it back a bit?

I was concerned as to how far away from the dormers to stop the slit. Each manufacturer has their own specs on this with Cor-a-vent being the most conservative again.

Would you hazzard a guess as to whether their conservative mounting locations---36' from dripedge and 12" from dormers is due to problems with their design encountered in the field?

Sorry for all the rambling. The roofers around here are not a good source of info. 99% of the ridge vents I see around here stop several feet from the gable edge and most don't have soffit ventilation---let alone something like this.


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## Noreaster (Apr 27, 2008)

One more question:

Should I use an intake vent product that is sited 5-6" from the gutter, will installing some sort of gutter guard product to keep the leaves out serve as a bridge for an ice dam? The ones I saw clip to the gutter on one side and tuck under the shingles on the other.

Thanks again!


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## Ed the Roofer (Jan 27, 2007)

Under typical situations, the most common application of the Smart Vent is directly at the eave edge, with the slot cut out fro the 6" to 7" point from the eave, continuously across the entire roof deck, except for at the soffit overhanng, which we still apply the product, but without the slot for a uniform appearance.

I have pictures on ContractorTalk.com in the Roofing sub-forum which show the ice hanging from the edges of the shingles, but not blocking the intake profile of the Smart Vent, and which also show a continuous blanket of snow coverage on the roof after a 14" snowfall the day before. I used the Shingle Vent II ridge vent, which the photos also show that the exhaust trough has melted the snow from the trough area, all the way to the soffit overhangs, where no heat was built up on the inside of the attic.

I will see if I can find that link.

Ed


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## Ed the Roofer (Jan 27, 2007)

This is not the exact thread I was looking for, but it should do, to ilustrate both the Smart Vent and the Shingle Vent II.

Here are some photos of the Smart Vent for intake, placed, along the eave edge on one side and as a mid-roof application on the other side and using the Shingle Vent II Ridge Vent on the entire ridge line.

http://www.contractortalk.com/showthread.php?t=37659

Ed


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## Ed the Roofer (Jan 27, 2007)

Here is the thread I really was looking for.

This one shows the house with a fresh 14" snow fall on it and how the Smart Vent remained clear and functional, while at the same time, the Shingle Vent II Ridge Vent allowed the internal attic heat to exhaust out and leave the snow pack unmelted on the roof surface.

http://www.contractortalk.com/showthread.php?t=31798

Ed


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## Noreaster (Apr 27, 2008)

Thanks, Ed.

When I see those pictures, I have to wonder what makes the DCI product work so well when the Cor-a-vent product---per the manufacturer---is supposed to be 36" from dripedge. Is the baffling in the Smartvent that superior to the IN-Vent?

I'm still trying to get through the "alleged" customer service reps to speak with someone at AirVent knowledgeable about their Edge product.

In some of the pictures, you can see gobs of ice in the gutters gathered at the top of the downspouts---the SmartVent doesn't seem to mind but what happens if you have a leaf-guard type product installed (as I was hoping to do) ? They are supposed to slip under the first course of shingles but if you tuck it under the SmartVent, does the expanding chunk of ice lift the SmartVent?

Thanks again Ed for singlehandedly helping me with this.


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## Ed the Roofer (Jan 27, 2007)

I have not run into the Gutter Guard scenario yet while utilizing the Smart Vent. DCI Products also manufactures a Flow Free gutter filter, which I have never used, but that style has gotten some positive reviews from the www.AskTheBulder.com web site authored by Tim Carter.

All in all, I don't buy into most of the Gutter Guard products. I have found the plastic sectional pieces with the laminated window screen style filter to work the best and at about 1/20th the cost.

Contact Paul Scelsi at Air Vent. [email protected]

I didn't look up his e-mail, but I think that is it off the top of my head, and the phone # is 1 (800) Air-Vent

Ed


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## Noreaster (Apr 27, 2008)

Ed:

I tried to send an e-mail to that address but it was returned.


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## Ed the Roofer (Jan 27, 2007)

I was close. I forgot the numeral 1, in the address.

Ed



Email: [email protected] 


Nickname: Air Vent Seminar Leader


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## Noreaster (Apr 27, 2008)

Ed:

A million thanks!

I received an e-mail and a phone call from Paul. He answered all of my questions in depth. He was great!

Thanks you, again!


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## Ed the Roofer (Jan 27, 2007)

Yes he is a great resource to have available.

Did you by any chance mention where you got the contact info from?

I was just discussing some Air Vent features I want to utilize in a forthcoming project and he is helping me out tremendously.

Also, if you have to contact DCI about the Smart Vent, speak with Jack Henderson over there and get the answers about the gutter guard questions directly from the horses mouth. I am conducting some ongoing temperature reading results from using their product also.

Ed


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## Noreaster (Apr 27, 2008)

I didn't want to get you in any trouble so I was trying to be discreet--- I just said that someone on an on-line forum, after seeing I wasn't having much luck with customer service, was kind enough to forward me his e-mail address

I wish I could e-mail you a drink :thumbup: 

Thanks again!


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