Under-roof venting - advice needed.

We're buying a house (upstate NY) where there's been some damage to the wood planks near the top of a cathedral ceiling from condensation. [There is no attic and the place was uninhabited and without heat for 18 months]
The building inspector said that the ventilation "appears less than satisfactory with only one gable end vent and questionable soffit venting. We recommend additional year-round under-roof venting be installed".
A roofer who looked at the work, suggested installing a Cobra II Ridge vent where required and cover with a shingle ridge cap.
I have noticed that there's some dissatisfaction with some roof vents. I understand that in combination with soffit vents ,a ridge vent can work well. But there again, we're not sure how effective the soffit vents are.
What would you recommend? Is this Cobra II ridge vent the way to go?
Any advice is greatly appreciated.
Tony
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7h95g wrote:

I do not know anything about Cobra roof vents. I have never heard of that name, so I can't give you advice about that.
I can tell you that a roof needs venting for a number of reasons, the condensation you mentioned is one of them. A ridge vent is a good start. If both the Soffit vents are in good condition and there is good air circulation between the soffits and the ridge, the ridge vent is all you need. Check the soffits to make sure there are no nests blocking air entry, and if you are able to, try to verify that there are no obstructions between the soffits and the ridge. Check each soffit!
What you are looking for is good air movement throughout the roof cavity. Having soffit vents and a ridge vent is one way to go. It allows the cool air to enter at the lowest part of the roof, the soffit. As the air heats up it rises and flows out the ridge vent.
In the summer time, this will lower the overall temperature of the roof, helping to keep the house a little cooler, and minimizing heat caused damage to asphalt shingles, and other roofing material.
In winter, heat that leaks into the roof cavity from the house and doesn't escape to the outside, can melt snow and ice on the roof. When the melt runs down the roof and hits a cooler section, it freezes and forms an ice dam. As more snow and ice melt, the ice dam grows, and forces water into the roof sheathing, and potentially into the rest of the framing. In extreme cases, the damage can include water flowing down the walls and soaking into the floor material.
(This happened to my Mother-in-laws house. A cheap roof fix, instead of a proper one, resulted in a main door that would not open/close without excessive force, warped and buckled hardwood flooring, and mushrooms growing out of the drywall.)
I hope this helps,
Carolyn
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Carolyn Marenger


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Carolyn Marenger wrote:

cobra is a commonly used roof vent in our area and it does work well. you said the soffit vents were questionable....why? I would suggest adding soffit vents if possible. the last issue that you really can't do much about without a lot of trouble is providing an air space between the insulation and the roof sheathing. at any rate, i think the ridge vent is a good start.
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marson wrote:

Tony,
Actually, the original poster's building inspector said the soffit vents were questionable. I said to check them to make sure they allow air flow, that they are not blocked by nests or other objects.
Yes, the ridge vent is a good start. Good to know that Cobra is a good vent.
Carolyn
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Carolyn Marenger
Webzine development: www.fivecatsproductions.com
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7h95g wrote:

Before you go too much farther into how to vent, check http://www.buildingscience.com/default.htm
The Building Science Corporation web site is based on research. TB
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snipped-for-privacy@bellsouth.net wrote:

Where in Upstate NY? I was born in Canastota, NY
10 years ago I bought a bunch of proper vents. These are made from egg carton type foam and are used to ensure airflow past the insulation. Because I had so many of them I completely did my attic from soffit vents to the ridge vents. I immediatly saw a major differance even before I insulated. Temp in my attic dropped on average of 25 degrees before insulating. When I built my shop I took it a step further by proper venting the entire under roof deack then took heavy duty aluminum foil and covered them. I never needed to insulate after that. The proper vents I bought wholesale were around .36 each.
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Raider Bill wrote:

Anywhere north or NW of NYC and Westchester Co. is upstate! :-)

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in Hamptonburgh, NY
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Willshak wrote:

That's a fact. Where I'm from is referred to as central NY. We think of upstate as Watertown, plattsburgh area and down by the city as the southren tier
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Raider Bill wrote:

We have to use that designation when we travel outside of the state because when you say you are from New York, they assume you are from New York City. :-)
I'm in the Hudson Valley.
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in Hamptonburgh, NY
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Willshak wrote:

Roger that! Same here. I don't want people to think I'm from the 51st state.
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There's no question that adding a ridge vent will be worth the cost (by keeping the insulation dryer it will actually lower the heating bills) but the inspector is also questioning the soffit venting. I would trust his instincts and look closer at improving the soffit venting as well. You may find that this will consume the better part of your venting dollar.
A good philosophy to follow is, you can never have too much venting in an attic, and good air flow (not blocked or restricted).

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First, thanks so much for all the replies and advice.
The house is inbetween Delhi and Oneonta.
Tony
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I've also been told that if you have ridge and soffit vents then gable vents are not needed and actually are counter productive.
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