Attic thermal barrier...cheap.
 

Seen the Reflectix stuff. Seen the stuff at Home Depot that has the wire grid in it. Both options seem to work but at a premium cost.

Why can't one just use some of those Mylar space blankets and staple those in place instead? I see you can git those fer about $1 fer a 4'x7' section on eBay. You might even be able to git the used ones at a marathon fer free... :D

I've seen people using space blankets as reflective curtains. They said it worked well.

Honestly I dont think the reflectix stuff is that expensive. Yes it's essentially 2 pieces of aluminum foil and some bubble wrap, but it's been proven to work.

On the other hand, for a few dollars and some staples, it might be worth a shot!

Perhaps some reflective panels on the roof itself? Why stop the heat from entering through the ceiling when you can keep it out of the attic altogether?

I just did some experimenting with some space blanket material on my skylight as a reflective material to help keep my house cooler.

I thought it was a great idea, but the space blanket material ended up "melting" to the glass and turning clear in most spots!

http://gallery.me.com/benhdvideoguy/...12789545650001

I used another piece on my downstairs window, and that works great! What's the difference? I think the skylight gets A LOT more light than the window. I don't know if the angle of the glass had anything to do with it.

The other thing I would check on is the flammability of the space blanket material. Take a small piece, and hold a cigarette lighter to it. See what happens. Now imagine an entire attic like that.

Actually, a white color works best for that: Cool roof - Wikipedia, the free encyclopedia

And, "Although a cool roof has been demonstrated to be more effective [2], a radiant barrier can be a less expensive retrofit."

Radiant barrier - Wikipedia, the free encyclopedia

Well...I've been using a single sheet on my truck to keep the sun out. I have it on the outside and it's kind of a pain to put it on since it's so lightweight. I did notice the one time I sprayed the truck down with water that the aluminum sorta melted away where the water contacted it along with the glass so I have clear spots in the sheet, too. Maybe some condensation is what happened to the piece you put in yer skylight? Is the piece you installed have the metal grid in it? ;)

As far as putting it on the roof...I think the weather would beat up pretty bad in short order...since I'm here in Houston. Hurricane, tropical storms, and a daily deluge of wind/rain would probably shred it as soon as I got off the roof. Besides...I currently live in an Home Owners Association (HOA) and they would probably kill the idea before I even got out the ladder. :(

I was curious, so I just test-burned a piece of scrap space blanket material.

It didn't burn as well as I thought it might have. The heat makes it shrink and crumple, but it still takes a bit to light.

It did start to actually burn, but the fire didn't "take-off" the way it could have.

In my very rough, non-scientific test, I would say that the space blanket probably isn't any more of a fire hazard than craft-paper-backed fiberglass.

Although it would not be as cheap check out Untitled and go to products "RavenWindow". About a year ago I watched a presentation by them from some university that was broadcasting it online (I watched online in my "End of Oil science class").

Try using aluminum foil.

In my case, I still wanted to be able to SEE THROUGH the window. The space blanket material is actually NOT opaque - it's more like those mirrored sunglasses.

For an attic, maybe aluminum foil would work fine? It would be interesting for someone to test it and find out.

Maybe line half the attic with aluminum foil, and half without, and then use one of those fancy thermal cameras from below to see the difference!