One of the issues with having a detached garage with no shade is that it heats up pretty quickly once the sun hits the roof. In the middle of summer, I was detecting temperatures inside well over 102F. Even though I recently installed an AC, without proper insulation, it's just a losing battle so pretty much anytime the outside temp is above 85, I was simply not going to spend any time inside the garage and certainly not going to waste energy trying to run the AC.
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| Radiant Barrier Installation - 9-6-2021 |
To attempt to fix this, I picked up enough radiant barrier foil from Attic Foil to cover 1000 square feet, more than I'd ever reasonably need but having more is always better than not having enough. The theory was sound, place the foil just under the roof stapled to the rafters such that there's an air gap in between, and the reflective nature of the foil would significantly reduce radiant heat from the roof surface. It's relatively affordable so it was worth a try. I was hoping for maybe a 10F drop in temperature at the roof.
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| Temperature right under the roof surface |
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| Temperature on the bottom surface of the radiant barrier |
I really didn't want to deal with installing this myself even though it's really just a matter of cutting it to size and stapling it to the rafters so I decided to hire some help in the form of
Barry's Handyman Services. We had been chatting about this project online and he was very responsive and reasonably priced. When he showed up, what a crazy surprise it was to find out we knew each other. Barry is an OG S2000 owner and we used to see each other at S2000 meets all the time when those things were very active in the region. He still has his S2000 and he immediately recognized my car when he saw it in the driveway.
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| Radiant Barrier Installed |
Anyway, back on topic...covering the entire roof took around 5 hours mostly because I had a few obstacles up there that needed to be worked around. I have about 95% coverage since it's recommended you leave a bit of the bottom and top parts open to allow air to pass and used up maybe 70% of the material I had purchased. You can see how dramatic the difference in temperature is. Shooting my IR thermometer onto the surface of the roof I was seeing temps of almost 122F in the middle of the day after it had been baking in the sun for at least 6 hours (ambient air temp around 83F). The surface of the radiant barrier foil just a few inches away almost matched ambient of 83F. That's about a 40F difference! We kept the garage door shut and the AC running during the install and you could noticeably feel how much better it was getting as more and more of the surface was getting covered. This is no replacement for a properly insulated ceiling (something I might consider next) but having 40F less heat being radiated from the roof to the rest of the garage really helps the AC keep up. It's never going to be frigid cold but it takes a lot of the edge off, like the garage was under the shade or something. I know this isn't the most pleasant thing to look at but it beats getting roasted inside your own garage. I'll monitor the temperatures over the next few warm days since I have data from all summer to compare against. If this is really effective, then I think adding an attic fan and an insulated ceiling will get me to ice cold status inside the garage if/when I need it.
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| Barry's business card |
Overall I'd give this project a solid 10/10 for bang for buck. You can absolutely install this yourself if you have the patience to do so. You just need a ladder, scissors and a staple gun. I'll probably use the rest of the foil to add some barrier to my shed next. If anyone needs a general handyman in Northern NJ though, I'd definitely recommend Barry. He's an honest guy that's very responsive, shows up on time, and gets the job done. It was also cool catching up and talking about old times.
