Monday, August 10, 2015

Living Green in the Southwest: Paint Your Roofs White

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In a previous post I said that painting your roof white is debatable. It reflects heat in the summer but how does it do with keeping the house warm in the winter? The people I know who have done it are happy in the summer and the winter. 

A Mother Jones article Cool It on the AC Already: How air conditioning is making us hotter supports using white reflective paint on your rooftop. Their point: "We spend $11 billion on cooling each year and release roughly 100 million tons of carbon dioxide in the process—the same as 19 million cars." The article gives the usual recommendations: turning up the thermostat, using fans . . . painting your roof white.

This first video should have been edited to cut to the chase: the difference between the temperature of an unpainted roof and a painted one. The difference is dramatic!

This next video is a how to and the how to is pretty simple. The example is that of a flat top roof but painting a pitched roof is the same. (BTW, it takes a lot of water to wash a roof so this may also be a good time to put in some gutters and use rain barrels to water your yard or garden.) 

Right now this strikes me as an early morning project or one that can best be done in the cooler late Fall. 

And btw, the Mother Jones article says that evaporative coolers are best in drier climates. Most of us in El Paso know that if we own an evaporative cooler. The concern is the amount of water that is lost when cooling this way. I use a bleeder hose that I can move and water different parts of my yard and garden. Just saying.


  1. I painted my roof white 4.5 years ago. I did it myself. It is SO much cooler in our house! Try it you will like it.

  2. I'm a big believer in white roof paint on flat or shingled roofs. The utility savings in the summer outweigh any utility cost in the winter. My slanted roof shingle house in El Paso had white roof paint applied in 2008 and it's still going strong. At about $2,700, it cost a fraction of the about $12,000 it would have cost for new shingles, so it's much cheaper in the long run just for the roof cost, let alone the utility savings from having a white roof. In about 10 years from the first application of white roof paint in 2008 (2018), I'll just apply more white roof paint and it will cost less than $2700 because the paint will be applied over relatively smooth older white roof paint atop shingles instead of directly on the relatively rough shingles. A neighbor also has white roof paint on a slanted roof, and after 10 years, he alone on a long weekend repainted his entire roof with a 9" paint roller on a stick, saving a bundle of money. The Home Depot video says to not apply white roof paint over shingles. I applied over shingles as have many others. The Home Depot video says to apply a black primer first. I did not, applying the Home Depot Henry brand white roof paint or Lowes Black Jack brand white roof paint directly on the shingles as many others have done. The shingles just can't be brand new shingles or the paint won't adhere as well. If the shingles are at least a month old, there's no need for a primer. The Home Depot video said to use caulk and mesh to bridge the gap on small gaps. I simply apply aluminum tape and then paint over the tape and surrounding areas with white roof paint. It's cheaper and quicker than caulk and mesh. I have a metal storage shed with lots of gaps on the roof in which some rain was coming in. I taped over all the large and numerous gaps and then painted the shed roof with white roof paint and there were no more rain leaks and the shed stays cooler. A bad rain leak on the house roof was how I got into using white roof paint. The bad rain leak could have been cured with an expensive reshingling of a rain leaking "valley" on the roof of about 10' x 3' area. Instead, I just applied white roof paint with a 9" paint roller on a stick directly on the shingles, like you'd use a 9" paint roller on a stick to paint a wall or ceiling, and the water leak was solved easily and inexpensively, not to mention ecologically. What followed next was painting the entire roof, and goodbye rain leaks. If anyone has a question about white roof paint, you can call me at 915-747-7740. Leave a message if I'm not available.

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