I recently wrote a piece on keeping some of the summer sun's heat at bay with English ivy on the side of my garage. I got a lot of feedback on that post; a lot of readers e-mailed me about ivy's insidious nature. I should have pointed out that I sealed the grout first. I'll still keep an eye on it.

This week's PRS article is also about keeping the house cooler -- with a product called radiant barrier paint.

I've heard that you can buy it pre-mixed, but they had it in powder form at the paint store I deal with. The salesman told me it was cheaper in powder form, and you know how I like to squeeze those pennies... I want to hear Abe squeal.

I got it at a good discount because I have an account with them. At the time, I was operating a small remodeling company, so I enjoyed the savings. But here's a tip: when you go to the paint store, open an account, and you'll probably save money. I have a DBA, but in my neck of the woods you don't have to have one to get a commercial account. You can be "Joe's Painting Company".

After the jump: how to mix and apply radiant barrier paint, as well as details on why it works.

How It Works

The radiant barrier powder I used is made up of microscopic aluminum chips and porcelain beads. And it's light. When you pick up the bucket, you would swear it's empty. The powder is mixed with latex paint: preferably white, I'm told. I'm not convinced that the color makes much difference in the attic, though.

The concept is that when the sun's radiant heat enters the house, the combination of the aluminum chips and porcelain beads reflects it, or a good deal of it, right back out.

Where can it be applied? Anywhere the sun impacts your home. The only place I have applied it to my house thus far is to the roof decking inside my attic. Has it done any good? Yep, my air conditioner got a well deserved break.

But imagine if I painted the exterior walls on the interior of the house! Also, if your house has siding (mine is brick), and you painted it, the sun wouldn't stand a chance. The experts say that a single application reflects up to forty percent of radiant heat.

Mixing the Powder and the Paint

The first thing to do is mix it with the paint. My bucket contained a gallon of powder. The recipe was one bucket of powder to five gallons of white latex paint. Now, mixing it is where you want to be careful. This powder concoction is very nasty to inhale.

Remember how light I told you it was? It is incredibly easy for it to go airborne. You must use a respirator for this step. You'll need another bucket, preferably a little bigger than five gallons because the way to mix the powder with the paint is a method called "boxing paint." I know, weird term.

Pour two and a half gallons of the paint into the spare bucket. Do this inside your garage, or some other place with no air current. Now (with your respirator on), ladle half of the powder into the paint. Use a paint stirrer to mix it slightly, not too much. Now, pour more paint from the original bucket into the mixture. It should be about two inches from the top.

The process of boxing paint is to mix it by pouring it back and forth from bucket to bucket. Do this a few times. Then pour one half way again, add the remaining powder, and continue to box the paint. Do it until you think, "Man, this is really stupid and my back hurts." That's a good indication that you're done.

Spraying the Paint

Fall, winter, or spring is the right time, because the attic won't be as blistering hot.

It's best to use an airless paint spray rig. The tip will need to be a bit bigger than usual, because of the particulate matter in the paint. In my attic, the roofing nails are sticking through, so rolling it wasn't an option. Of course, if your roofer cut corners and used staples, you might get away with rolling it.

If you spray, you'll want to wear a respirator, goggles, and a ball cap. My paint rig is the kind where the intake tube sits in the bottom of the five gallon bucket. Since there's always a bit that it can't get to, I painted the remainder on the inside of the garage (yeah, that "ivy wall").

In most cases, the whole job will take less than a day; I think I spent about five hours. Was it effective? Heck yeah! My electric bill didn't go down much, because that was when they started tacking on those crazy "fuel surcharges." But my KW usage went down. Give it a shot: you pay once, but save forever.