My house is hot in the southern United States. Trying to add insulation in the attic space during the summer almost killed me last year. The attic was so unbelievably hot. I have developed a roof leak and was thinking about a metal roof on top of my current roof. I was wondering why a metal roof can’t be installed on braces a few inches above an existing roof to function as a roof and shade. The airflow between the two would have to cool the attic, much better than if the heat radiated through straight to the shingles and plywood. We bought a sunshade for our back patio, and I’ve thought about even something as simple as that over smaller homes could drastically help.
In: Engineering
There’s no theoretical reason you couldn’t other than it would have to be a structure that’s larger than the house that would have to stand up to tough weather, and shade isn’t always desired.
They actually do exactly this with RVs in some places because RVs are not as well insulated and take a total beating in the sun. So at some of the nicer RV parks in the Southwest were it gets really hot they have covered RV spots to get the RV out of the sun.
In practice, local codes are not going to be your friend on this kind of thing, and your HOA will probably go effing crazy if you tried it…
Any big wind will get underneath it and tear it off and likely take some of your house with.
Also it sounds expensive, so does the insurance.
Most houses already have that air gap youre talking about. There’s the shingles, an attic for your air gap, then your insulation.
What kind of insulation did you add in your attic?
If you targeted the shade specifically to the parts of your house that would benefit the most from it (the windows) the idea you’re proposing is essentially [awnings](https://wikipedia.org/wiki/Awning). They’re an excellent source of cheap cooling, but they fell out of style when air conditioning became broadly available. Perhaps they’ll become popular again in the future as the cost of cooling continues to rise.
You’re essentially describing what your existing roof is supposed to do. There should be air circulation in your attic. Yes, it will get hot, but there should be a way for that hot air to escape and cooler air to enter. Maybe you just need better attic ventilation.
An envelope design works well. I don’t know about the return on investment. But, I would come home to ours and it would be 82 degrees, outside in the teens. Passive solar also.
Why aren’t white roofs standard, since they reflect the heat?
I add a whirlibird vent on my roof in the summer. When I cut the hole in the roof, I felt as if someone had turned on a hair dryer and was blasting me with it!
I’ve thought about that.
I also want to know why roofs in the south aren’t white to reflect some of the sun.
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