Attic ventilation is an important part of the overall health of your home. Without adequate attic ventilation, many problems such as mold, water rot, ice buildups, water leaks, and holes in the ceiling can develop. These problems result in costly repairs and even sickness (in the case of the mold) if not prevented. With effective attic ventilation and controlled heat loss, however, a homeowner can see great savings on heating bills, as the temperature in the attic is controlled by the natural airflow.
Attic Ventilation Principles
The reason attics need ventilation is because they get too hot. This is a problem in the summer because it warms your entire house and raises your cooling costs. It is a problem in the winter because it can not only invite unwanted moisture into your attic but potentially melt the snow on your roof, causing it to flow down into your gutters and refreeze, in a dangerous phenomenon known as an ice dam.
The challenge of attic ventilation, then, is to remove this hot air while allowing fresh, cool air to enter from the outside. The way to get the air out is by placing exhaust vents on the roof. This works because hot air rises. You need new air to replace the old, though, and that comes in through vents in your soffits or attic walls. A proper balance of intake and exhaust such as this will maintain the proper airflow in your attic.
There are a few different do-it-yourself projects you can do to get your attic ventilated. Some of these projects are fairly involved, but, with the right tools, they can be done without a lot of problems.
There are a few main ways of exhausting air from the attic. The first of these are static vents, of which there are two main types: ridge vents and roof vents. A ridge vent is installed a few inches below the ridge of the roof on both sides and runs the length of the roof, allowing a continuous means for the stale air to rise up and out of the attic. As opposed to a ridge vent, a roof vent is limited to one spot on the roof, ideally in the middle.
A turbine vent is a type of roof vent that can actually suck the air out rather than simply providing a passage for it. It does this with the help of the wind, which causes it to spin, creating suction on the inside of the attic. Another vent that relies on a "natural" power source is the solar roof vent. That neither of these ventilators uses electricity is both their strength and their weakness. If there isn't a lot of wind or sun, they won't work.
The next type of attic vent is a powered attic vent. These rely on electricity to pull hot air out of the attic and often come with a thermostat, so you can set the vent to operate under certain conditions. The same can be done with an attic fan, which, in contrast to exhaust vents, goes on the gable wall. These are powerful enough to remove air without the help of gravity.
Installing a ridge vent or a roof fan is recommended for quality attic ventilation, but will not do much if there is no way for fresh air to enter the attic. If you have no soffits, you can allow fresh air into your attic through vents on the gables of your home. If you have soffits, though, they will almost always be the ideal location for your attic intake vents. Like exhaust vents on the roof, soffit vents come in continuous and stand-alone varieties.
Note that if you do lack soffits and rely on gable vents for your intake, a ridge vent will not provide sufficient exhaust. You will be better off with one roof vent near the center of the attic. That's it! Now that you know your options, you can pick and choose which ones work best for your attic and your budget.