A few weeks ago when it was warm outside, I stepped from the house to the garage and was surprised at how cool it was. Our garage was cooler than the house. Granted, the air conditioner was off inside and the windows were open, but the temperature was markedly cooler. Monday afternoon, I walked in front of our garage and was hit with a wave of heat. It felt like I was standing in front of a heat lamp!
The reason for this is the radiant barrier I placed on the garage door last summer. It literally reflects the sun’s heat right back into space, keeping it from getting trapped in the garage. This radiant barrier is essentially a roll of bubble wrap with aluminum-foil backing. It cost $25 for a roll that nearly covers my garage door. I am still amazed at how well it works!
Monday morning I ventured into my attic to retrieve the broken attic fan I put up the year before (you remember, the one that almost claimed my finger). Rather than replace it, I’m considering buying more foil and stapling it to the rafters in the attic.
It is so much easier to cool a house if you can keep the heat out of it to begin with.
The radiant barrier in your attic will prevent the sun from warming your house. It’ll be like you’re in permanent shade. Then again, your unwanted heat gain in summer probably far exceeds your beneficial heat gain in winter.
One more thought. You can’t attach the radiant barrier to the underside of the roof because of all the roofing nails poking through. If you attach it to the rafters, you’ll have a pocket of hot air trapped between them. Will that cause any problems due to lack of air circulation?
There is relatively little heat gain from the attic in winter. The sun isn’t particularly strong during winter in the northern hemisphere, and there’s the little fact that heat rises!
Nails aren’t an issue with this foil. It would actually save me staples! Putting it close to the sheathing would avoid the problem of too much dust rendering it ineffective. Stapling it to the rafters is done in such a way that gaps exist at the top and bottom for airflow.
There are many schools of thought on this, however, and I will consult many of them before making the leap.