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.
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,
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.
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
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
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.
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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