- The first is energy savings. During warm summers, your attic could actually be heating your house, resulting in high, unnecessary energy costs coming out of your pocket. Proper attic ventilation gives that heat somewhere to go, resulting in a naturally cooler home.
- The second reason to pay attention to your attic ventilation is the effect poor ventilation has on your roof’s performance. Under vented attics get very hot in most summer climates and can bake the shingle from the inside out.
- The third reason for installing the correct number and placement of vents is so moisture does not get sucked in through some of the vents. Moisture can actually get caught in the attic that can results in damage to your ceiling and roof structure.
- The fourth reason is to reduce the probability of moisture build up in the attic from condensation.
The other day, I was inspecting a roof that had reported a leak. While looking in their attic, I found an actual blanket of snow covering the floor of the attic. This was the result of the attic being over ventilated at the ridge. Because there were too many turtle vents on the roof, the attic actually started to intake air, and moisture along with it. Snow was being pulled into their home during storms, causing obvious issues with moisture content. This is the first time I had ever seen anything like this. The problem could have easily been avoided if the roofing contractor had been more educated about attic ventilation principles.
Under ventilating your attic can be just as dangerous, and is much more common. If your attic does not allow air flow, your attic would stay unnaturally warm throughout the winter. This could cause snow on your roof to melt off and then refreeze in your gutters and at your eaves, which may force water to freeze up under your actual shingles. In the summer, your attic could reach temperatures above 160 degrees, heating your home as you are trying to cool it. The overwhelming heat of your attic could be prematurely aging your shingles or ‘frying’ them from the inside out. Not only this, but if your attic gets hot enough, you could even warp the framing on your home.
Proper ventilation is simple to enforce. The biggest mistake I have seen homeowners make is to build a roof with proper ventilation and then install insulation covering the soffits (the area adjacent to the eaves where the air enters the attic through the soffit vents). Another similar mistake is storing items that block the soffits. This makes the ventilation system worthless. Instead, be sure to install insulation clear of this area and store your items away from the vents to allow proper air flow.
By far, the best way to ventilate your attic is to use soffit vents at the eaves and ridge vents. These vents are installed by your roofing contractor. Soffit vents are installed on the bottom of the overhanging area of your roof, or the eave. These should be used to intake air, as they will not intake moisture along with it. Your outtake vents should be your ridge vents at the peak or highest points of your roof. These will help to cool your attic, and as they are covered with shingles, they will also avoid the intake of moisture. This system will keep the air in your attic moving and flowing, maintaining the health of your home.
How can you tell if you have proper ventilation in your attic? One way to monitor this is by keeping track of the temperature in your attic. An ideal temperature in the summer would be less than 20 degrees warmer than the outside temperature. It is ideal to have the winter temperature the same inside as outside the attic, as to avoid ice dams. The winter temperature is probably the most important to monitor in terms of up keeping your home and roof.
Another way to measure ventilation is by a floor space to ridge ratio. There should be 1 square foot of ventilation along your ridge for every 300 square feet of floor space in your attic. For example, if you have 1200 square feet in your attic, you should have 4 square feet of ventilation along your ridge.
Following these tips and precautions should save you money on your energy bill and in unnecessary repairs to your home.