Did you know your roof consists of much more than just plywood and shingles? Unless you are a roofing professional or have participated in a roofing project, you probably have evaluated the need and intricacies of roof vents.
However, just because you may now know all there is to know about them does not mean they are any less important. It is important to understand what they are, how they work, and why they are so important to your home in Michigan.
What Are Roof Vents?
These vents help to release heat and moisture that build up in the attic space of your home. Even if there is not an attic you can access, your home likely has some space between the ceiling and the roof.
Your roof has two forms of vents, the intake vents and the exhaust vents. The intake vents are usually in the overhang of the roof. However, some homes also have vents built into the wall of their attic space known as gable louvers.
Exhaust vents come in a couple of different varieties. The most common vent is the ridge vent, which goes across the ridge across the top of your roof. The second is called roof louvers, which are installed right on the surface of the roof, with a cutout in the sheathing board to provide the actual ventilation.
How Do They Work?
The mechanism by which these work is quite simple. Intake vents are located lower on the roof structure, which the exhaust vents are located toward the top. Warm air naturally rises, creating a vacuum that air exhausts through the vents. This is natural ventilation and is what many homes use.
However, in some circumstances a mechanical method more effective. If your roof is designed in a way that does not allow much airflow, or if you are in an area with little natural air movement, this will be something to explore.
Mechanical ventilation utilizes fans to move through the space. These typically install in the vent cap and require some power source. Some models simply tie into your home’s electrical system, while others may have self-contained power like solar.
Benefit #1: Improve Energy Efficiency
One important benefit of roof vents is improved energy efficiency. Removing the stagnant air from your attic helps improve the efficiency of your HVAC system, especially during the hot summer months. By moving the hot air out of the attic you reduce the amount of work your air conditioner must exert to cool your home.
This also reduces the humidity in space, reducing the environment conducive to mold development. This improves your indoor air quality making it more comfortable in your home, but also improving the efficiency of both your heating and cooling systems.
Benefit #2: Add More Life to Your Roof
A normal asphalt shingle roof can last up to about 25 years, depending on how it is maintained. However, when the roof is not properly vented, this life is cut significantly short.
As discussed above, an improperly vented roof will cause ice dams, which will cut the life of your roof on its own. However, it goes well beyond that.
During hot Michigan summers, the extra heat gets trapped underneath your shingles. This extra heat causes the shingles to degrade prematurely, shortening their life and causing leaks.
This degradation also causes the shingles to start peeling up from the roof, weakening the seal of the tar strip on the bottom. This makes the shingles more susceptible to additional damage from wind and storms.
Benefit #3: Reduce Indoor Hot Spots
It is challenging to heat and cool your home appropriately when you have unusual areas that are warmer than others. This is especially true if you have a multi-level home and one floor is warmer than another. Sure, hot air rises, so expect some amount of variation from floor to floor. However, you should not feel a dramatic difference between floors, and especially not between your ceiling and your floor on a single floor.
While this change may be a problem with how your HVAC system is running, it can also indicate an improperly vented roof. If you experience this dramatic change, look for other signs your vents are not sufficient.
How Many Do You Need?
Unfortunately, a single vent on your roof will not be sufficient for most homes. Rather, you need vents periodically across your entire roof. But how many will you need?
You need to know some information about your home before you can determine this. Specifically, you need the square footage of your and if you have a vapor barrier in your attic space. If you do, then you need to plan for one vent for every 300 square feet of roof. If you do not have the vapor barrier, then you need to install one for every 200 square feet.
You should also know the pitch of your roof. If your pitch is greater than 6:12 then you will need more vents to cover the attic space properly.
