Aluminum foil roof?

[CobraBall]

If you live the SW USA , Texas, NM, AZ, purpose built reflective foil on the underside of the rafters will give you the most bang for the buck. I typical 100+ day can yield 160F in the attic. Properly installed foil is supposed to reduce attic temperature down to the ambient temperature. Insulation?? Once the foil is done, you may forget the insulation.

Foil on top of the roof? Three possible problems: neighbors, city codes, winds.

CB

[aerohead]

Originally Posted by WaxyChicken

Every year here in Arizona the temperatures soar in the summer time to around 120F. The heat is just as much from the sunlight as it is from the ambient heat in the air.

So here's my question:
if i were to roll out and staple down some shinny aluminum foil on my roof - the entire roof - then would that reflect heat out or would the foil only heat up after just a couple of hours and bake the house?

getting enough aluminum foil from the $1 store to do the whole roof would only cost me between $20 and $40.

(but it's probably piss off the neighbors because they'd get even more glare on their windows.)

I'm going to weigh in on the side of light colored roofing,and perhaps a spray-on radiant barrier on the underside of the roof deck.With the low pitch it sounds like you couldn't access parts of the attic if you had to.Avoiding all the load you can will pay dividends.Whatever you can do to insulate and ventilate will also pay you back,even if you have to shove the material in with a broom stick.You may have watering restrictions to stretch the Salt River,and so your not likely to be planting Burr Oaks to shade the house.Artificial xero-scaping,adding any manmade shading devices to any exterior sun-exposed surfaces will, as others have mentioned, give you some immediate relief.And I also advocate the swamp-cooler over refrigerated air,so long as all the golf courses,agriculture,and swimming pools have so altered the climate that they'll no longer function.

[akcapeco]

I like the foil idea... it would spare you having to wear the foil directly on your head, which would look really silly.

[shawn187]

Originally Posted by WaxyChicken

getting enough aluminum foil from the $1 store to do the whole roof would only cost me between $20 and $40.

(but it's probably piss off the neighbors because they'd get even more glare on their windows.)

Im here because I was thinking about this today. I have done something similar but it was on a RV roof. When doing a major repair on the RV roof I accidentally purchased a product called Peel and Seal (reflective) I thought I was getting the white stuff but I was happy after thinking about it for a min. Note that the white stuff is exactly the same but painted white. This comes in rolls and has a tar backing. IMO I think its perfect for what you want to try and wont look that bad if you use a heat gun to help conform to your existing roof. AND.,. if you don't like it you can paint it white or any color you like and keep the reflective benefits.

I look at the heat problem the same way the people who make fire suits do. Less insulation needed if you reflect the heat away.

ABOUT THE ATTIC FANS These are a bad idea no matter what way you slice it. I myself figured this idea was good until researched it. Bottom line is: Negative pressure in you attic will draw inside a/c up and out. You just cant seal enough to make it worth it. It took a lot of research to make my mind up about this one but.... Google: "do power attic fans work" Answer NO

Don't give up on the foil idea its going to work!

[NeilBlanchard]

It probably has already been mentioned, but making your roof white [raises] the albedo.

[sid]

Both the Florida Solar Energy Center and the federal government have done tests and released the results on the net that show that white roofs save considerable energy in areas with high air conditioning requirements over any other color. These same studies show that white asphalt shingles, while performing better than other color shingles, still perform much worse than white metal or tile roofs.

Also, tests by the Florida Solar Energy Center show that properly installed radiant barriers on the underside of the roof do considerably reduce attic temperatures. But they still recommend at least R-19 insulation installed above the ceilings.

The Florida Solar Energy Center is funded by the state of Florida and may be a direct government organization.

[t vago]

Originally Posted by NeilBlanchard

It probably has already been mentioned, but making your roof white lowers the albedo.

Huh? White reflects more electromagnetic energy in the visible spectrum than any other color. How can making your roof white lower its albedo?

[Ford Man]

I know this is an old thread, but someone had revived it so instead of starting a new thread about basically the same thing, I just wanted to know whether anyone has installed radiant barrier to their roof and what kind of results you got. I'm getting ready to install a new metal roof on my home which will be installed on firring strips above the existing roof which will leave approximately a 1" dead air space between the existing roof and the new roof. Everything I've read on the internet says the dead air space is necessary to receive the benefits of the radiant barrier. I installed Prodex insulation to the interior walls and ceiling of my garage at the home I used to live in and could tell a noticeable difference in the temperture of the garage even without any a/c or heat, so what I'm looking for is opinions of how well it will work both winter and summer if placed on the exterior of the roof. The main reason I'm going to the exterior instead of the attic space is because I live in a modular home and have no access to the attic to place the radiant barrier directly above the living space. I'm interested in hearing from anyone who has used radiant barrier in their attic or especially in the application I am thinking about.

[sid]

I have installed a radiant barrier on the underside of most of my roof. I stapled it to the bottom of the roof trusses. Since my roof has a rather shallow pitch of 3 in 12, which is typical for a lot of older Florida houses, I couldn't do this closer than about within 2 feet of the eaves, since that is where the roof trusses overlap the ceiling joists. Since my house is only 24 feet wide and has a hip roof, that leaves about 20 % of the roof with no radiant barrier.

Still, it probably reduces the attic temperatures during the hottest part of the summer by about 20 degrees F. It is noticeably cooler in the attic, but it's still hot up there. So additional insulation on top the ceilings is still needed.

[NeilBlanchard]

Hi,

Originally Posted by t vago

Huh? White reflects more electromagnetic energy in the visible spectrum than any other color. How can making your roof white lower its albedo?

I mistyped, and I have now corrected myself. Higher albedo closer to 1 reflects more heat and light; while a lower albedo closer to 0 absorbs more heat and light.

Kinda like open ocean water has a lower albedo than snow and ice.