Current best practice for roof vents?

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It's the integral of heat over time.
My front shingles facing north still looked good after 25 years, when my rear shingles facing south looked terrible. I could only see the roof from the front, or from the rear if I was up on a ladder.

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family in the sun drenced phoenix report roofs dont last long there, the sun bakes them out.
metal roofs arent common either cause they tend to warp.
ceramic tile roofs there are supposed to be the best and last a 100 years if properly installed to begin with
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Home Guy wrote:

I'll disagree to the extent of scrapping the turbines. You are correct that they don't work as efficiently when there's no wind - although some heat escapes through those 18" holes - but when there IS a wind, they will move an enormous amount of hot air. Plus, they do it at no electrical cost!
As for cosmetics, they can sometimes be installed below the ridge line so they're not easily visible from the street.
And speaking of ridges, be sure to install a ridge vent. These are dirt cheap and will probably give you the biggest bang for the buck.
Note: None of these suggestions are meant to be exclusionary. Do 'em ALL.

Again, I'll slightly disagree. You're correct that one can't have too much soffit venting.
The usual standard is one sq ft of soffit venting for every 150 sq ft of living space. If you've got a venting area 4' long and 6" wide on the soffit, that's 2 sq ft. BUT, you've got to subtract the screening area. If hardware cloth type screening, subtract maybe 10% of effective venting. If it's that HardiPlank stuff with itty-bitty holes, subtract 98%.
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actually not.
exhaust fans with ridge vent is the tops for inefficency. the fans just suck the air from the nearby ridge vent, and that doesnt really ventilate the attic.........
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" snipped-for-privacy@aol.com" wrote:

That could very well happen.
But the same could be said regardless if the fan is wind-powered or electric-motor powered.
A fan that pulls outside air through the ridge vents and then exhausts that air right back outside will nonetheless create air currents inside the attic and it will lower the temperature of the warmest part of the attic - the area in the peak or top part.
If you have a ridge vent then you probably have an inverted V style roof, which means you could mount a fan on the side wall of the attic (or both side walls) and have it blow outside air into the attic, thereby helping to force the hotter attic air up and out through the ridge vent.
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wrote:

This is horrible advice. It demonstrates the understanding of basic physics.
Forcing air from an "outside wall" inward would be taking in elements such as water from something God created called rain. The fan would pull water from the louvers of any vent.
You have absolutely no concept of building practices. You're nothing but a hack.
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wrote:

Let me reiterate. It demonstrates the lack of basic understanding of physics.
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Chet wrote:

So you're saying that a fan that's mounted flush to a vertical wall, with a screen, and probably with a rain shield mounted over it's exterior opening, is going to pull in air with such force that it's also going to draw in any rain that just happens to be falling at the time that the fan is being commanded to turn on by the thermostat that's controlling it?
Did you ever consider the fact that if it's raining, that its probably cloudy, and your attic fan controller might not sense that your attic space is hot enough to require the fan to be turned on?

What exactly are you smoking?

You have little to no concept of physical reality.
I suggest you start taking your medication before your dimentia gets worse.
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HeyBub wrote:

Anyone that likes to get a tan in the summer will know this:
When the sun comes out from behind the clouds, the wind mysteriously dies down. Then when the clouds come back - so does the breeze.
That fact doesn't help you when your chosen method of active ventilation is wind powered.
Attic fans (typically 1/8 or 1/10 hp) consume pennies of electricity a day. Worth the cost when they give you a reliable, dependable CFM of air movement when you want it.

Depends on the style of roof.

Once upon a time, soffits were faced with 1/4 plywood, and you had to buy and install screened vents that were visible and you had to do a nice job of cutting the hole and positioning and installing the vents so you wanted to install the minimum necessary if you were the builder.
But it was a pain in the ass as a home owner to paint the soffits every 5 or 10 years so you got them covered in aluminum, and with slotted sheeting it wasn't a hassle anymore to create venting anywhere you wanted it - including the entire length of the soffit. The only problem is that unless you cut more holes in the original plywood facing, the extra aluminum venting will do you no good.

For new construction, you don't even need to put the 1/4" plywood facing on the underside of the soffit any more. Just mount your J-channel and slide the perforated aluminum soffit sheeting into place.
The problem with having one vent every 4 or 6 rafters is that you won't get much airflow along those rafters that don't have a vent down at their soffet end. Air will preferentially flow along those rafters that do have a matching vent where they meet the soffet.
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