attic ventillation, keeping it cool

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FiremarshalRob

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Mar 25, 2008
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Baton Rouge, LA
I built my home in 2001. My attic ventilation is the traditional ridge vent system. I have ridge vents on every peak of my roof and all of my vinyl soffit is vented.

I am brainstorming ways to reduce the heat in my attic. I live in Baton Rouge, and its been ridiculously hot this June so far. Last June we hit 100F 3 days in a row, actual temp in the shade.

I am considering:

1. Foaming the attic. Covering all vented soffit with the spray foam and the rafters and ridge vents. I would leave alone the double layered R-30 on the attic floor.

2. Adding an additional layer of "Green Fiber" spray in cellulose to my attic floor (I know I definitely need some extra insulation where I have 6 recessed lights).

3. Adding some square or circular soffit vents to the existing vented soffit all around the house.

4. Adding a non-powered (wind driven) turbine or 2 to my roof. But I've read not to do this is you already have ridge vents.

Any thoughts, opinions, or prophecies would be appreciated. I'm just trying to stay cool this summer and keep lower my electricity bill.
 
I have a friend that put that silver reflective bubble stuff in his attic. He stapled it to the underside of the rafters. Said it made a good differance in his attic. Then three months later I saw a house getting a metal roof and guess what, they were putting that reflective stuff down first. I guess it reflects the radiant or infared heat waves. never tried it myself but thinking about it. You said in your first idea covering all the vented soffit,rafters, and ridge vent with spray foam. If you did this how would you get any ventilation?
 
They even sell a solar roof fan that works excellent. They have a thermostat on them also, and use no electricity.

More commonly is an electric fan..
 
Firemarshalrob,

Please allow me to join in with your pain with too high heat in the attic and the second floor of my house.

I was going to ask about attic fans as I am tired of the 8 degree difference between the first and second floor (bedrooms) of my 19 year old home.

I had a new roof installed 11 months ago (thank you September 2008 90+ mph windstorm) along with ridge vents. It's still hotter than Hades, especially in the garage. The garage has blown-in insulation and as far as I know, the soffit vents are not blocked. I had four (4) box vents installed along the roof line of the garage, though right now, one would be hard-pressed to believe it there is any type of venting that is occurring.

Absent a whole-house fan, I was thinking of having a thermostically controlled attic fan installed in both the house attic and the space above the garage.

Ridge vents, while widely touted by roofers, do not seem to be venting much of anything.
 
I live outside of Redding Calif and it gets hotter than hades so I doubled the area of soffit vents and roof [Ridge] venting area and it helped. What really helped was putting up RADIENT BARRIER stapled to the underside of the roof not blocking the vents. It is really cheap and makes quite a difference.
 
Thanks Steve.

So, the solution seems to be either installing a radient barrier or a thermostatically controlled attic fan.
 
Originally Posted By: firefighter
I have a friend that put that silver reflective bubble stuff in his attic. He stapled it to the underside of the rafters. Said it made a good differance in his attic. Then three months later I saw a house getting a metal roof and guess what, they were putting that reflective stuff down first. I guess it reflects the radiant or infared heat waves. never tried it myself but thinking about it. You said in your first idea covering all the vented soffit,rafters, and ridge vent with spray foam. If you did this how would you get any ventilation?

The idea would be to totally encapsulate the attic and no ventillation would be required. No hot air would enter, none would need to escape. I'm not saying NO hot air, but just to totally seal off.

Originally Posted By: dkryan
Thanks Steve.
So, the solution seems to be either installing a radient barrier or a thermostatically controlled attic fan.

My fear with a temp controlled fan would be creating a negative pressure within the attic space and sucking cool air from my house into the attic through the little nooks and crannies by lights, fans, recessed lights, etc.

I do agree with the radiant barrier suggestion, but it has to be done right to work. The placement of it is critical to make sure the natural ridge ventilation system will continue to work.
Also, I'm told your cell phone reception will be drastically reduced in your home.
 
I think planting the correct kinds of trees, if available, would benefit the most in the long term. You've already got several short term ideas that might help. I get a little nervous with adding fans to a roof structure, as you're adding another potential leak point.
 
Originally Posted By: FiremarshalRob
My fear with a temp controlled fan would be creating a negative pressure within the attic space and sucking cool air from my house into the attic through the little nooks and crannies by lights, fans, recessed lights, etc.

I do agree with the radiant barrier suggestion, but it has to be done right to work. The placement of it is critical to make sure the natural ridge ventilation system will continue to work.
Also, I'm told your cell phone reception will be drastically reduced in your home.


I totally agree with you on both points. I've read on another website that attic fans could possibly pull cooled air from inside the living areas of your home.

And yes, placement is critical. Finding someone qualified to do the work is 80% of the task.

As for cell phone reception, I believe it. We had new double-hung, low-E, argon gas filled windows installed last November. They look and perform great. However, my XM radio antenna struggles to maintain a consistent signal when, in the past, signal strength was always consistent. Some claim it's the low-E coating, some say it's the argon gas. Either way, you gain on one side and lose something on the other!
 
so none of you guys have ridge vents or ventilated soffits?

Just use a smaller fan, you don't need a hurricane up there!

Ours turns on at 90 degrees, so it only runs when it's really hot.
 
Another option is a fan in the access to the attic.
this pulls air from the house, and forces it through the vents.
It makes a big difference in attic temps.
And there is no need to cut the roof .
 
Originally Posted By: SteveSRT8
so none of you guys have ridge vents or ventilated soffits?

Just use a smaller fan, you don't need a hurricane up there!

Ours turns on at 90 degrees, so it only runs when it's really hot.


Yep, I have a ridge vent that runs the length of the roofline. The roofer said it would not be productive to install a ridge vent along the peak that runs atop the master bedroom, mostly because it would only be 12 feet or so in length.

I should have forced the issue last July when the new roof was installed. I'm having a roofer install a ridge vent along that section of the roof this week.
 
on some houses a large powered attic vent can actually draw alot of air from the living area of your house. You want plenty of soffit vent if you go this route.
 
I installed ridge vents and increased the size of the soffit vents . Then installed radient barrier stapled to the underside of the roof , the total job made a real big difference.
 
Originally Posted By: Steve S
I installed ridge vents and increased the size of the soffit vents . Then installed radient barrier stapled to the underside of the roof , the total job made a real big difference.


You increased the size of the EXISTING soffit vents, as opposed to ADDING additional vents?

Did you install the radient barrier yourself, Steve, or have someone do it for you? Regardless, what brand (type) did you have installed?
 
Keep winter in mind. If you use a temperature controller on your attic fans, have a way to easily adjust it. There are going to be some days in the winter that the attic will heat up quite nicely, and you don't want to lose all that free energy.
 
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