In your quest to make your home more eco-friendly, you've probably heard a lot of advice about roof replacements or retrofits. These can supposedly help your roof stay cooler, last longer, and hand off less extra summer heat to the inside of your house. However, some of the popular advice is incorrect or incomplete, and sometimes it only works for certain kinds of roofs.
Here are three common myths about roof retrofits and a larger view of why commonly heard advice may or may not work out for you.
1. Attic Fans Will Reduce Overall AC Usage
A well-ventilated attic is one of the keys to a healthy roof and can also reduce heat gain through the attic. Some homeowners have bought into the idea that this means forcing as much air through as possible using an attic fan. However, in some cases this can do more harm than good, so be sure you know all the ins and outs of your situation before deciding on one.
The idea is that an attic fan will help pull more outside air into the attic or roof space through the intake vents, cooling the roof off even more efficiently. But if you have existing exhaust vents, adding an electric fan could pull air into the attic from the nearby exhaust vents rather than the intake vents. This can leave the majority of the attic practically unventilated.
Another issue is when the attic fan pulls air so strongly from inside the attic that it encourages precooled air from inside your home to enter the attic through attic bypasses, such as the areas around ductwork, plumbing vents, and wiring coming into the attic from below. Pulling this cooled air into the attic can actually put more of a load on your AC unit.
2. DIY Radiant Barrier Installation Improves Passive Cooling
Although radiant barriers can indeed reduce the amount of heat that your roof transfers to your living space (and thus reduce your AC energy usage), they only function if installed correctly. A DIY installation can run into a number of problems, some of which you may not realize are preventing the barrier from functioning.
This is because a radiant barrier works by reflecting radiant heat rays traveling through the air, much in the same way that a mirror reflects light. However, if the rays aren't radiating through the air, it can't reflect them. So if it's in contact with the underside of the roof, the heat will be able to travel through the barrier easily by means of conduction and its effect will be nullified.
Likewise, if you install the barrier too far away from the source of the radiant heat, it won't be able to reflect the heat strongly enough to get it back out through the roof, and instead, the heat rays will just bounce around the attic, heating up the space more and more. A professional installation can help you avoid these and other radiant barrier installation problems.
3. Cool Roof Coatings Are Always a Good Idea
Cool roof coatings are always an option, but you should discuss with your contractor whether or not applying one to your roof will be worth the cost. That's because cool roof coatings work much better on some roofing types and situations than others.
In addition, a cool roof coating isn't always an unmitigated improvement- as with so many things, real life isn't that simple. For example, a cool roof coating could void your shingles' manufacturer warranty or eliminate the warranty's coverage if anything goes wrong with the installation. So if your warranty is still in effect, you might want to think twice.
Having a reputable roofing contractor to help you sift through the advice you hear online and provide a complete picture can allow you to make the best possible decisions for your roof. To learn more about how we can help you and your roof thrive, contact us via phone or email today.