Attic ventilation

Hi,
I have been reading several posts as well as asking several people and I can't seem to get a clear answer as to what the best thing to do in my scenario...
I recently went up into my attic and almost passed out from the heat.
So I started to do some research about attic ventilation...
Currently I have perforated soffit separated about every 4 feet around my house, 1 gable vent on the N.side of my house and 3 small roof vents...
I really don't understand why my attic would be so hot.
I figured the best thing for me to do was to close up all the vents (the 3 roof vents, and 1 gable vent) and add a ridge vent as well as continuous soffit.
Can anyone tell me if this is the best way to correct the heat issue in my attic?
Thanks
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How cool do you want it? I wouldn't close up the roof and gable vents. Adding more soffit vents is a good start and adding a ridge vent will contribute somewhat to the air flow.
Having worked in many attics in all kinds of weather conditions I can honestly say that the most comfortable attics to be in during the summer are the ones that have whole house fans. The attics that have the mushroom type ventilator fans are definitely cooler than attics that do not, however the attic is still not comfortable enough for long term human habitation. The attics that rely solely on natural airflow are unbearable.
Your attic is hot because the Sun beats down on it all day and there is no insulation to keep the heat from penetrating inward. Additionally the attic is traditionally at the top of the house. All of the heat from the Sun hitting your siding rises upward. Any interior heat rises upward.
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John Grabowski wrote:

John, what do you mean by "mushroom type ventilator fan" ? Are you referring to the wind-powered turbine style fans ?
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No. I was referring to a powered attic ventilator such as this model from Broan: http://www.broan.com/display/router.asp?ProductID $66
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I have seen places on the net that suggest the use of a powered attic fan can draw cool air from the interior living spaces causing the A/C to have to work harder.These people suggest that natural ventilation and plenty of attic insulation are best. http://www.abbeyinspections.com/news3.html http://www.dom.com/customer/efficiency/res/pdf/attic_ventilation.pdf http://www.chicagotribune.com/classified/realestate/homeimprovement/chi-0404020269apr02,0,6582347.story?coll=chi-classifiedhomeimprove-hed
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digitalmaster wrote:

Are you confusing an attic fan and a whole house fan? An attic fan is mounted in the roof or gable, and sucks the hot air out of the attic. Replacement air comes in through the soffits; not from the home's interior. Unless your soffits are very poorly vented, AND you have a very leaky attic floor, it's hard to imagine an attic fan drawing air from the interior living space.
A whole house fan is mounted in the ceiling of the top floor, and sucks warm air out of the home's interior and blows it into the attic where it vents out through the roof vents and soffits. The (hopefully cool) replacement air comes in through open screened windows.
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Home Repair wrote:

I'd start by making sure there is adequate soffit venting. Next, I'd put in the ridge vent. Personally, I would not close up the other vents when putting in a ridge vent. There is the theory that the air will short circuit from the other vents, then out the ridge. I've yet to see a convincing case made that in practice that actually happens. I would think there is so much hot air in an attic, that it's gonna be rising from the soffits and going out any way it can, ie throught the existing vents or the new ridge vent. At the very least, I'd try just adding the ridge first, before looking for more work.
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Home Repair wrote:

I have considered adding a ridge vent but, from the ones I've seen, they're alot of work to install. If you don't already have one, you'll need to rip off the top shingles and a few courses down, cut through the plywood/decking along the whole ridge, both sides, then install the vent, and re-shingle all that was removed.
It might be easier and cheaper to add continuous soffit vents and then a fan in the gable end, making sure there are enough soffit vents to serve the gable fan. Even if you need to cut a louvered opening in the other gable end, it seems alot easier to me.
James
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Home Repair wrote:

It is impossible to answer your questions from here without a lot more information from you.
You need to know how much free area venting you have on the soffits. The total roof area. The area where your home is located - Texas will be a lot different than Mane. Total area of the roof vents and gable vent as well as the construction of the roof (pitch)?
You did not say how hot "so hot" was. What was the inside and outside temperatures.
If you have not been in a few attics in the summer during the afternoon you may not have a good idea of what the usual attic is like. That is one reason they recommend so much insulation below the attic.
--
Joseph Meehan

Dia duit
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Hi,
I just installed an attic vent fan today, and the attic and roof were very hot, I think I lost 5 lbs and my son/helper put his foot through the ceiling trying to show the homeowner how the thermostat worked, so noe I'm a sheet rocker fixer.
Anyway, on the the subject, I know for a fact that attic ventilators work, doing heat and air repair, I'd much rather be in one with powered ventilation than with those turbine looking things, that won't work if the winds not blowing, even if it's a 1000 degrees in the attic.
So, when it came to my own attic, I checked out all the attic fans at the different hardware stores, and decide to build my own.
My house has 3 gable vents, 2 large (30" h x 60" w) and 1 small one, so, since I own an HVAC company, I have access to a large number of fans and motors, so I decide to take a motor/fan combo from a unit I had just replaced and since 220 volts uses less juice than 110, that's what I used, might not be a good choice for tha DIY'er, but could be, so after installing my fan and wiring it up, I checked the intakes and man were they suckin or blowin, which ever it was movin some air.
So I proceeded to maximize my heat remover by closing off the space around the fan and other vents that allowed air to escape to quickly, so after all was done, I believe I dropped my heat gain by 1/2 to 1 full ton.
Then, another idea hit me, since I wrap my ductwork in foil back insulation, why not my house? Since the foil will reflect heat, might it work for the attic? So, I grab a roll of my 4x100 feet of wrap and began to lay it out on the attic floor, after a full day of rolling out 1 1/2 duct wrap, the attic floor is covered, nice and shiny, now how does it feel in the house, and I have to say, I believe I've taken another 1/2 ton off the heat gain index of my 3000 sq ft house.
I'll do a new load in a few days and see if I still need a 5 ton system, might be able to do the same job with a 3 ton.
Oh, and about an attic vent fan pulling air through the ceiling fixtures? I've never really checked other peoples house, but with my 3/4 hp attic fan, not one bit of house air is going through any ceiling fixture, so I can safely say, I doubt any of the little hardware stores 1/16 hp attic vent motors are pulling house air throught ceiling fixtures either.
Sorry for being so long, it's just I do this stuff everyday, for 30 something years now.
Later
Home Repair wrote:

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Hi
To answer some of the questions that one of the other posters asked, I live in PA, where there are times where it can get extremely humid (not like the south).
Anyway, I don't ever recall my parent's home being as hot as my attic was on very humid days. I don't know how hot it was in my attic and next time I will take a thermometer.
All I can say is I don't think I have sufficient soffet after inspecting this weekend. We are currently looking into replacing the gutters and soffet, so I will opt for a continuous soffet.
As for the ventilation, I just may need to add another gable vent to the sound side of the house and see how that goes for a while.
I know it is hard for anyone to read others issues and find a definite solution, but from all the research and comments from this thread, definitely have enough ammo to start...
Thanks to all for your input...
Travis
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Here's some info on how poorly ventilated some new homes are. I was out looking at new houses with a friend yesterday. Homes being built by two different builders caught my attention because of apparent lack of ventilation.
On set of houses had ridge venting on only a fraction of the roofline, maybe a quarter of the total. For soffit venting, at first I thought there was none. They were using what appeared to be solid vinyl siding to close off the soffits. Upon closer inspection, of a nearby piece, I could see that there actually were tiny little slits, about the width of a credit card scattered about. But I mean really scattered about to the point that it's hard to imagine any significant air flow. I would say the open air flow percentage throuugh this material had to be a few percent. This was all the ventilation, no gables vents, additional roof vents, etc.
Later we saw a second house by a different builder. That one did have a continuous ridge vent, but it was also done poorly. On one side of the lengthwise 2X8 at the peak, it had a opening about an inch wide. On the other side of it, less than a half inch wide. They used one of the roll type ridge vents, and the material appeared very dense. Questionable how much air could get through that. At the soffits, they were using the same vinyl product with the tiny and widely scattered slits. It was a nice 70 degree day and the attic was hot as hell. The attic also contained the upstairs A/C.
These were $800K- 1.2mil homes. It amazes me that this kind of crap can pass a building inspector.
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