I'm getting ready to have a new roof installed (tear-off old and replace), and had a question. Right now my roof does not have ridge vents, it does however have several passive vents ("turtle" vents?), plus one atfic fan with a thermostat. The soffets are vented also.
Should ridge vents be included in the new roof?
The ridge vent should not be used with other roof mounted or gable end vents. They can disrupt the air flow through the attic. A properly setup ridge/soffit vent system does not need to have power roof vents to help move hot air out of the attic. Whole house fans work great with a ridge/soffit vent system. We do not consider them the same thing as the power roof vents.
How do I figure how much ridge vent I need to use? Take the square footage of house under roof X .48 divide this number by 20 (for V-600 products), by 17 (for V-400E or X-5) or by 13.5 (for V-300 or Fold-A-Vent products) this will give the lineal feet of product needed to meet a 1/150 vent ratio. If you are only going for a 1/300 (code minimum) vent ratio divide the above result by two. REMEMBER there MUST be an equal amount of soffit vent (in NFVA) to balance the ridge vent.
Hope that helps
Clark
Have a nice nail over ridgevent installed. Loose the turbines and fan. The fan will suck ac air out of your house by causing negative pressure in the attic.
I go into a lot of attics. The ones that rely solely on ridge vents for air flow are always the hottest. I think that they are good to have for a minimal amount of air flow, but I would keep the other vents and attic fan as well to help bring the temperature down. Also good and many soffit vents are important.
"DesignGuy" wrote
Just hire HomeDepot to do the work.
There are two very different opinions on this and I've yet to see any actual study that shows which idea is right.
1 - The more ventilation you have, especially static vents, the better. The idea here is that hot air rises and will make it's way from the soffits out any top vents, be they ridge, gable, can vents, etc. So, if you have a gable or other static vent, leave it in place when adding the ridge vent. 2 - Having a ridge vent, with a gable, can vent, etc will shortcircuit the air flow, with air coming in the gable, out the ridge, without properly cooling the attic,I tend to believe in 1 myself. With a power vent placed close to another vent, like a gable though, I could see some short circuiting going on there, making the power vent not worth it.
If anyone has seen any actual test data, it would be interesting,
I find it hard to believe that SO much hot air will rise on its own to the ridge vent that the attic will be cool. A fan mounted close to the peak can only move more air. Doesnt seem like there should be controversy over it. Getting a new roof is expensive but how much will adding a ridge vent and and attic fan cost? Not much
You ignore cost of electricty to run the fan and conditioned air being pulled out of house.
have had several jobs with plenty of ridge vent and soffit vents still to hot . i put in next larger size power vent(s) than needed along with ridge vent and attic and inside home then stayed cooler in summer. lucas
Maybe you exaggerate. What if fan runs as directed by t-stat? And thus avoids roasting (literally the past situation in my house) roofing and framing?
Not to mention keeping things substantially cooler at peak temps above ceiling of floor below. Resulting in noticeably lower afternoon temp rise below on August afternoons. I'll take that any day.
A cheap and simple seal around door to attic, and your second phobia is toast.
Not to mention that the floor immediately below is "conditioned" by being opened to ambient at night with small fan assist.
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