Roof venting, ridge vent or power fan?

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I'm getting a new roof which of course has lead into the age old discussion of how best to vent it. I've got 2 contractors saying ridge only is best, the other insisting that power fans are superior. Personally, I can see advantages and disadvantages to both. I'm interested in other experiences and opinions.
So, here's the deal. The roof consists of 3 seperate sections. One of those is a cathedral ceiling, so using a ridge vent there is a given. The other two sections which are the area of interest are:
Section 1 - Currently has a gable vent in one end and a power fan near the other end.
Section 2 - Currently has a gable vent in each end, with a power fan blowing air out behind one of those gables. This section is over the 2nd floor bedrooms where keeping it cool is very important.
All sections have continous soffit venting, about 2" wide. All 3 roofers say that is sufficient and doesn't need to be improved.
Two of the roofers say to go with ridge vent on both of these roofs, get rid of the existing power fan.
One roofer insists that I should stay with using fans on the two roofs as it is now. His argument is that a power fan moves a lot more air than a ridge vent system can. Climate is NJ.
Thoughts?
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Like this? http://www.benjaminobdyke.com/resources/160/How%20Ridge%20Vent%20Works.pdf
How about both, putting pancake/muffin fans along the peak, to force air out of the ridge, on a thermo/humidistat? And controllable dampers at the soffit (point 6 in the pic). Intuitively, I think on very hot days, some power assist would greatly help.
Also, how bout a double-wall roof, about a 4" gap. This would radically reduce the heating load in the summer, as well, and could also be controlled with louvres, dampers. The attic would be more usable, climate-wise. This may elim the need for fans altogether.
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If you have a ridge vent, then THAT is the vent at the peak. You don't want other vents in the roof too, certainly not power vents and especially not anywhere near the ridge, because then air flows from the other vent that is nearby, over to the ridge and out. That doens't do anything to cool the rest of the attic. With a ridge vent the idea is that air enters the soffits and exists via the ridge, uniformly moving air.
Also humidity is not an issue with either the existing approach of going with a ridge vent.

By getting a new roof, I meant tearing down and re-shingling, not building a whole new roof.
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If you have a ridge vent, then THAT is the vent at the peak. You don't want other vents in the roof too, certainly not power vents and especially not anywhere near the ridge, because then air flows from the other vent that is nearby, over to the ridge and out. That doens't do anything to cool the rest of the attic. With a ridge vent the idea is that air enters the soffits and exists via the ridge, uniformly moving air.
Also humidity is not an issue with either the existing approach of going with a ridge vent.

By getting a new roof, I meant tearing down and re-shingling, not building a whole new roof. ======================================================= Well, when the shingles are off, they could just put some 2x4s on edge, and tack on the plywood sheathing. Then you'd have yer air gap. I've always wanted to do this for myself, but I got slate, which has about another 100 years left on it....
I thnk it's worthwhile looking into, and might not add that much to the whole roofing job. Course, you don't want your roof to be a 1,000 sq ft squirrel's nest, either.... lol
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On Thursday 21 February 2013 13:25 snipped-for-privacy@optonline.net wrote in alt.home.repair:

Passive venting beats active.
Reason?
Power venting might be "better". Until it goes wrong and stops working.
How many houses have you been into where the bathroom/showerroom fan has died? Even less people are going to care to mend a building structure fan. Until something goes rotten...
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That's a valid point, but not an issue here, because I'm only dealing with what I do. And if a fan craps out, I'll fix it.
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On 2/21/2013 8:48 AM, snipped-for-privacy@optonline.net wrote:

I agree with passive. My fan stopped working and I replaced it with a passive vent when I got new shingles. My neighbor was not so lucky. His caught fire. He might have died had other neighbor coming home late at night had not noticed it and alerted him.
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On Thu, 21 Feb 2013 05:48:41 -0800 (PST), " snipped-for-privacy@optonline.net"

As my brother in law told me once... why pay to move the air? Having lived in Long Island, I think ridge vent is better. And more important, if 2 outa 3 roofers like ridge vents where you are, I'd give that serious consideration.
And FWIW, I once had one in Texas and it stopped working... problem is, I don't know for how long before I discovered it.
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wrote:

conventional mushroom vents on the same roof. The mushrooms become inlets, and you get "short circuit ventilation" that does not properly ventilate the lower poertion of the roof/attic.
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wrote:

+1

No, it's not better. It's noisy and doesn't work nearly was well as ridge vent with the appropriate (amount of) soffit vent.

Some are nearly impossible to get to (both bathroom and attic). Go passive.
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my home had just a gable vent at either end, no soffits so no soffit vents and no ridge vent.
inside attic temperature around 140 degrees, used my fluke recording temp meter highly accurate...
got eve vent installed high attic temp dropped to 115 degrees.......
my ridge vent worked great
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Per snipped-for-privacy@optonline.net:

I am about 23 miles west of Philly.
We had two installs of power fans: one was in the roof facing upward and the other was in a "window" in one end of the attic.
Never again. The noise/vibration was not worth any increase in effectiveness.
With the roof mount, I mitigated it somewhat by detaching it from the roof and hanging it on bungees... but it was not enough of an improvement for me.
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wrote:

I've had 2 roof power vents in this house in the 16 years I've owned it. The original was replaced with a new one when I re-roofed about 10 years ago. Attic is about 1200 sq ft and batted. Neither one was loud.or vibrated.
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The ridge vent and other passive venting will only provide a minimal amount of air movement. If you want to be able to cool down the attic space in order to lessen your air conditioning load, then you need a powered fan. I have a ridge vent and also a mushroom type attic ventilator fan on the roof which definitely lowers the temperature of the attic in the summer.
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Years ago, I was helping install AC in second floor of a house. Air handler in the attic. We had a power vent put in by a roofing company. The day they put it in, I wired it to a temporary source of power. Turned it on, and the attic temp dropped many degrees, nearly instantly. I was really impressed how much good it did.
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The ridge vent and other passive venting will only provide a minimal amount of air movement. If you want to be able to cool down the attic space in order to lessen your air conditioning load, then you need a powered fan. I have a ridge vent and also a mushroom type attic ventilator fan on the roof which definitely lowers the temperature of the attic in the summer.
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On Thursday 21 February 2013 17:07 Stormin Mormon wrote in alt.home.repair:

Occurs to me:
Was the OP talking about a method of *cooling the attic space* (and thereby the house) or *venting the structure of the roof to prevent condensation and rot*?
Over here (UK) we concern ourselves a lot with the latter. But as people are mentioning aircon and stuff, I did wonder...
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Both. Reducing the temp helps with roof life and cooling bills, at least a little. Venting for moisture prevents moisture damage to the wood components, etc. OF those, the latter is the more important.

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On Thu, 21 Feb 2013 11:24:13 -0500, "John Grabowski"

required - and often as much as a powered vent. Hot air ALWAYS rizes. Good eave venta and good ridge or mushroom vents WILL ventilate an attic.
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I would assume, being in NJ, you do have cold (freezing) weather.
Here's some thoughts before you decide.
- If you decide on ridge vent (which I would suggest), you do not want the existing gable vents to act like the intakes even though you have soffit. I have seen where ridge vent was installed leaving the existing gable vents. During rain storms in hot weather, the natural flow of air actually pulled in the elements of water through the gable vents.
- Power vents are the absolute worst solution to use, where freezing climates occur. They don't work in the winter. A structure must be able to exhaust any hot air of the building envelope, which rises through the ceiling insulation in the winter. I believe I may have told the story in this forum of actually observing water dripping through ceilings in the winter, because the only type of ventilation installed was power vents.
If you do go with ridge vents, you must close off the gable end vents. You must make sure the soffit vents are cut through and unobstructed by insulation. In most cases, baffles are used in the initial 4 ft from top plate of the wall. This helps provide a continuous unobstructed ( think insulation) passage from the soffit intakes.
I guess you must decide what is the most economical, but it won't necessarily will be the best functional system. By this I mean if you must close off the gables, without ruining the appearance of the structure, and making sure you have clear intake passage from the soffits, makes enough sense for the money involved in doing it right. Otherwise, you may want to use another method of choice.
If it were me, I'd have to give some serious thought on just using the existing gable vents _without_ power vents (which block the vent in the winter), and putting ridge vent on the cathedral room. I would also give some serious thought to additional insulation where you can add it. Attic blankets are pretty economical.
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From the research I did today, it seems most credible sources agree with this.

Currently both roof sections that have fans also have a gable vent, plus the soffits. So, you have two openings up top for the air to exit. No moisture issues.

When I bought the house 18 years ago, that was one thing I caught and corrected. There were no baffles and the insulation was blocking the soffits. I installed baffles.

No problem with that. All that needs to be done is close it off from inside the attack.
and

Given all that I've learned researching it so far, I'm hjeading in the direction of going with the ridge vents. Next thing is there are all kinds of product, from rigid plastic ones that come in 4 ft sections, to ones that come in rolls. Oddly, the price is almost the same. I'm guessing that the roofers like the roll material because it's probably easier to install. However the rigid ones have more airflow, like 20 sq in per foot versus maybe 14 for the other stuff. And with the roll type, I think it would be easier to not install correctly, ie mash it down, etc so you could wind up with even less venting. So, if I go ridge vent, I'm going to spec which one.
Thanks for the help. And if you have any more tips, I'd be happy to hear them.
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