# Whats the purpose of a ridge vent?



## Magnettica (Dec 19, 2006)

I was just surfin' over at Craigslist (linked there from the Marketing & Sales section) and I came across this pic.

What is the purpose of this, and how does something like this get finished?


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## Tmrrptr (Mar 22, 2007)

It is someone's idea of a better mousetrap...
Use instead of gable end vents.
Or maybe if u got a LOT of heat buildup?

It takes a special kind of ridgecap... that's what they are selling.

r


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## Magnettica (Dec 19, 2006)

So will there be another small roof built over this or something?

I'm just trying to figure how it works without rain or snow getting inside.


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## reveivl (May 29, 2005)

There's a product that you can nail on over it that matches the shingles and vents the hot/moist air from the attic. If you're going to vent the attic the higher the vents are the better, hence the ridge vent.


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## roofwiz74 (Oct 27, 2006)

here.....http://www.airvent.com/homeowner/products/ridgeVents.shtml

as with any venting system you need all the componets for it to properly work.
the idea is fresh cooler air enters thru soffitt vents,travels up the bottom of the deck and vents hot humid out the top.


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## Same Old (Mar 9, 2007)

And in freezing climates it helps to keep the roof deck cool to avoid freeze thaw cycles on the eaves which can result in ice dams.


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## roofwiz74 (Oct 27, 2006)

i can see the roll of cheap stuff by the bundle.comes in a roll keep it a ft or 2 from the ends use 1 1/2" nails,don't nail the ridge all the way tight to the roof.
I try not to use the rolled stuff.I don't like the look of it.


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## Kgmz (Feb 9, 2007)

We use vented ridge on everything we build. I can't stand the look of those cheap square plastic roof jacks, especially when the roof needs 10 to 20 of them.

We do not use any roll vent, and use a low profile ridge vent that comes in about 4' lengths and is covered by your normal ridge cap.

I also believe the roof vents better with a ridge vent.


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## Same Old (Mar 9, 2007)

Do any of you guys use vented drip edge?


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## Ed the Roofer (Dec 12, 2006)

The link provided earlier by RoofWiz tells you most of what you need to know.

The purpose is to provide the proper amount of exhaust venting capacity to properly balance the proper amount of fresh air intake ventilation.

The purpose of ventilation for the attic is several reasons:

1) To create a sufficient amount of air flow pumping through the interior attic environment to evacuat any heat build up and humidity containing moisture.

2) To lower the interior home temperatures caused by the radiant heat effect caused by the trapped interior attic heat.

3) To remove the moisture contained in the interior environment which therefor will diminish the potential environment conducive to mold growth.

4) To exhaust the hot air contained in the attic to alleviate hot spots on the roof decking, which would promote accelerated snow melt over the heated portions of the decking, which will re-freeze upon traveling down the slope to the unheated portion of the roof decking, which is over the soffit overhang.

The best ridge ventilation products contain both an internal filter to prevent air and moisture infiltration from entering the attic. They also contain an integral exterior wind deflecting baffle to deflect the windward slope air flow over the top of the vent product. A secondary side affect of this external wind deflecting baffle, is to create an additional point of air pressure immediately over the baffle vents trough, which actually aides in creating an additional air flowage from the exhaust vent product.

When installed properly to the manufacturers specifications, this type of vent product will not allow any rain or snow to enter the attic.

Ed


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## Ed the Roofer (Dec 12, 2006)

I have tried the vented drip edge vent made by Air Vent Corporation, but now prefer the Smart Vent, by DCI Products Inc.

I am open to effective alternative intake ventilation solutions. Another member recently provided a link for a similar product to the Smart Vent Product, but I have not used it yet. 

Ed


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## apkole (Mar 18, 2006)

Ed,

I have used the vented drip edge with some success also.

I've been wondering about using Smart Vent in applications where I&W shield is used. The diagram in their ad shows a slot cut in the roof deck immediately above the plate. How does this work with the need for the 3' field of unbroken protection afforded by the I&W? I don't believe that ice dams can be completely eliminated in all weather conditions. Since you install in the midwest snow belt, you've probably got a good perspective on this.

Still scratching my head on this one. (Probably why I'm going bald, eh?)

Thanks for the feed back.

Andy


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## Ed the Roofer (Dec 12, 2006)

The Ice and Water Shield gets installed right on top of the Smart Vent. 

I have had ZERO problems with the functionality of the product nor have I had any consequences from any installation on any job to date.

It has now been about 4 years since my first usage of it and I am satisfied that there will be no liabilities due to the products specs.

I even installed it on a 3 1/2 twelve to 4/12 pitch shed style roof. That one is 3-4 years old now with no problems.

It does slow down the start to shingle time, since it is the first step before you can do anything else though.

Ed


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## apkole (Mar 18, 2006)

On those installations, was the Smart Vent installed on the leading edge of the roof? 

The diagram I saw showed the vent installed after the first six courses or so of shingles were installed.That would imply that there is a break in the continuity of the roof system.  Looked to me that if a dam formed, it would be right at that point in the roof where the vent and corresponding slot in the roof deck were located.


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## Same Old (Mar 9, 2007)

From their website:










It seems the sheathing slot and the SmartVent are all under the I&W anyway. Even if you had an ice dam it would be above two weather barriers. Looks like a pretty good product. It seeme it would certainly keep that roof surface cold. I think I'll try it out.


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## Ed the Roofer (Dec 12, 2006)

One tip for using it and making it more cosmetically pleasing.

On the side gable edges, install your ODE drip edge metal unnailed on top of the Smart Vent, so it covers up the side edge of the tapered product. It covers up the black vent product and the greyish colored filter like material so it does not stand out.

I have also used a double layer of ODE just to go under the Smart Vent and also on top of ir to accomplish the same affect, but also to ensure that the bottom edge of the lower portion of the gable fascia board was covered up.

Ed


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## apkole (Mar 18, 2006)

Same Old
Ok, I understand that application. But . . . . take a look at the mid roof diagram on the website. There in lies my question. Ice and water shield at the roof edge, four or five courses of shingles, then comes the SmartVent install. Looks to me as if any ice dam which forms might cause water to back flow into the vent and through the roof penetration. No?

We roof quite a few one story cape cod homes in this area. Lots of issues with venting. Some of these homes have 0 overhang, some have 6" or so, some as much as 10" - 12".


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## Ed the Roofer (Dec 12, 2006)

I have only used it along the eave edges where the previous photo displays it and also as an exhaust vent at the top edge of a shed style roof. 

I have had Zero problems with those two application methods.

I can not accurately comment on the mid-roof application, since I have never done that yet.

Try laying out some shingle on the ground and see how and where the cuts line up. I does not seem feasable to me until I have actually done it. 

So, I am apologize, I can not answer your specific question. I has made me ponder about that potential too. But, based on the eave edge application, I would think that if it were also covered with Ice and ?Water Shield, that it should be okay.

Sorry, thats the best answer I have at this experience factor.

Ed


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## Same Old (Mar 9, 2007)

I'm guessing the mid roof application would not be suitable in areas where ice dams would be a concern.


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## AaronB. (Oct 6, 2004)

That isnt even a drip edge in that pic...thats an apron.


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