All About Attic Ventilation

You put shingles on the roof to keep out the elements, right? Then why do roofers tell you to let air flow through your attic, no matter the time of year? The answer is really quite simple. While you want your home to be weather-tight, you don’t want your attic to be airtight. If your attic couldn’t breathe, it would trap both heat and moisture, neither of which is good for the roof or the contents contained there. Far from reducing the heat stress on your home, an airtight attic would work like a balloon by expanding in the summer and contracting in the winter. This in turn would undermine your roofing system and inevitably spawn leaks. This is why you need to place attic insulation on the floor rather than on the ceiling. If you’ve ever wondered about attic ventilation, let me tell you a thing or two. 


1.      How does an attic breathe? – While your attic has neither lungs nor gills, it does indeed breathe. Intake vents located under the eaves allow fresh air into the attic. Intake vents are usually installed in the soffit either individually or as one continuous unit that runs the length of the soffit. Gabled roofs may have vents located on the side of the house, within the peak of the gable. Exhaust vents located atop the roof allow hot air to escape the attic. Known as passive ventilation, this system promotes air exchange. As a rule, your attic should have 1-square-foot of vents for every 300-square-feet of attic space. Exhaust vents come in three varieties: Static vents, ridge vents & powered vents. Static vents often protrude from the roof like metal mushrooms, due to the covers that are meant to exclude precipitation. Some static vents contain wind-powered blades meant to suck the air out of the attic any time the wind blows. Ridge vents are a little harder to see since they run the length of the roofline. This type of exhaust vent works by leaving a screen-covered gap in the sheathing that runs along the ridge. Powered exhaust vents use electricity to power an exhaust fan whenever the temperature inside the attic reaches a preset limit. To keep from adding to your electric bill, some of these units are solar-powered.

2.      Why does an attic need to breathe? – There are basically three reasons why air needs to flow into and out of your attic. In the first place, if hot air gets trapped in your attic, it will add to the amount of time your home air conditioner needs to run in the summer. This will not only cost you more when you pay your utility bills, but it will also reduce the life of your home’s HVAC system. Secondly, without adequate ventilation, condensation can occur in your attic. This can lead to several problems, including mold, damage to the attic insulation, not to mention potential damage to your roofing system and supporting timbers. Thirdly, trapped heat in the attic can cause snow, ice and frost to melt only to refreeze along the eaves, potentially undermining the shingles that are affixed there.

3.      How can you tell if your home’s attic is improperly ventilated? – The first sign of inadequate ventilation would be an uptick in your utility bills. If your electric bill suddenly went sky high or your home’s heating and/or air conditioning system seems to be running non-stop, it’s possible that your attic ventilation has been compromised. This can happen in several different ways. The vents could be clogged with dust or debris. This is fairly common in the autumn when the leaves are falling from the trees. It’s also possible that squirrels or other wildlife decided to build a nest on or inside one of the attic vents.

attic roof

4.      How often should you clean out your home’s attic vents? – If you want to maintain the optimal efficiency of attic ventilation, it’s a good idea to clean out the attic vents once a year. This can be done by using a can of compressed air to blow out dust, dirt, and loose insulation that can compromise ventilation by partially clogging the ridge vents. Soffit vents are best cleaned out with a broom. You may need a vacuum to clean out-static vents, although you may first have to remove the cap. Before you turn on the vacuum, take the time to inspect the vent with a flashlight to look for any obvious obstructions. If there’s a clot of leaves or a nest blocking the vent, you don’t want to suck that into the vacuum since it could clog it. If you can’t get your hand down the stack to remove a clog, try using ice tongs. 

Hi, my name is Nicole Corson and I am the owner of RoofCrafters Roofing and a very blessed mother of two beautiful daughters… and a handsome dog! In 2013 I decided to pivot when I had an opportunity to take my 12 years of experience in property management, property maintenance, and my passion for helping others by applying it to the roofing industry. Coming into a predominantly male industry, I am very proud to say I have created some much-needed structure for all our team and an exceptional customer experience for my clients

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