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.
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We just had 28 solar panels installed on the roof, 7′- 9′ high. They shade about 80% of the house. Inside temperatures dropped by about ten degrees.
Secondly, we can run all 6 air conditioners as much as we want now for free.
It’s a 2 story concrete house with a flat roof, we gained a huge veranda upstairs. Nice cool ocean breeze in the afternoons and it’s higher than most mosquitos fly.
Maybe put the insulation up in a season other than summer? That costs a LOT less than putting a second roof on.
I imagine wind could create problems, so you would need to be able to retract it on windy days.
Look into insulated roof panels with an air gap and IR-reflective foil. I’ve install these on a number of buildings to reduce attic or cathedral ceiling heat gain. Continuous airflow from eave to ridge. Then you can install the new shingles directly on this. No issues with wind uplift or excessive structural load. An example is Hunter Cool-Vent panels:
https://hunterpanels.com/products/roof-products/cool-vent/
You can put awnings on your doors and windows. They went out of fashion long ago and nobody does them now.
Shade trees and better attic ventilation. The trees are going to take a while, so look into better ventilation for your attic. If your attic is hotter than the outside air, then it should be flowing outside in at the eaves and outside air at the peak. There are passive and active ways of doing this. The advantage of the active way is that you can shut it off in the winter to keep the heat inside the attic.
My house has this. It’s called a Snow roof. We live in an older double wide mobile home and the people who installed it also put a pole building around it with a steel roof. It’s designed to take a heavier snow load than the mobile can take.
The gap between the mobiles roof and the snow roof works exactly as you described in the 110° heat we’ve been having. It creates air movement across our roof and keeps the sun from hitting it directly. We can usually keep the inside of the mobile 20° to 30° cooler than the outside temperature without AC. These are pretty common around here for mobiles installed in the 80s.
You could but whatever you built would have to be sturdy. Roofs that don’t let wind under them easily blow away, imagine if you had an umbrella mounted over the house. It’s just asking to blow away. Other than that, it’s an extra cost up front and something that needs to look good while working well enough to justify the cost. It’s easier to just choose white roofing if that is important to you.
What I find amazing is that old-fashioned awnings are rarely seen in my neck of the woods. By shading the window of direct sunlight it really cools the home or prevent it from getting overwhelmingly hot. They could be considered ugly, but they are so effective.
There is no reason, its just when these homes were built it was not a priority. The second rood doesn’t need to be permanent. It can be something made out of something very reflective like a fabric that you then install on anchor points that blocks the sunshine.
Sunshine has a lot of energy. A patch of sunshine the size of a yoga mat has roughly the same energy as a space heater. You can fit a lot of yoga mats on a roof. When that sunshine its a structure, some of it bounces off as reflected light, and some of it is absorbed where it becomes heat. Dark surfaces absorb this sunshine, really light surfaces reflect this sunshine. Roofs are generally made with dark surfaces that are good at absorbing sunshine and converting it to heat.
2000 square feet of sunshine after 10 hours.
If your home was under a large highly reflective white shade tarp, where during the daytime, none of the sunshine even touched your home, it would be significantly cooler. All the energy it would absorb from the sun would bounce back into space. It would still be sitting in a hot fluid (the air surrounding the home) but it would not be absorbing the energy from the sun.
On the flip side, in the winter months, the sun is valuable. You want your home, particularly the inside of your home to absorb sunshine in the winter months at is free heat.
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