Installing Soffit And Roof Vents
MATERIALS: Roof vents, soffit vents, screws, roofing cement, roofing nails
TOOLS: Ladder (or scaffolding], straightedge, hammer, reciprocating saw, drill with bits, screwdriver, roofing knife, saber saw
Proper air circulation is essential for effective insulation. If you have inadequate venting, warm, moist air that escapes through the insulation condenses in the cold, attic air. This trapped moisture can cause wood rot, mildew, and water damage. You can also have exterior roofing problems, along with higher cooling costs in the summer.
A balanced circulation system will have 1 square foot of venting for every 150 square feet of attic. (Change this to 1 in 300 square feet if the insulation has a vapor barrier.) You should have an equal amount of soffit intake and roof exhaust vents. Check for blockages of airflow in your attic vents, baffles, and roof vents. Also verify that attic insulation doesn’t block any vents. Vents range from static open units to thermostatically controlled electric fan units. The type of vent you purchase will depend on the amount of air you need to move, the size of your attic, the scope of the project you wish to undertake, and of course, your budget!
SOFFIT BLUES - Insulation saves me money. So, I’ve put in a lot of it over the years and advise my neighbors to so the same. A lady from across the street told me she insulated the attic but she was having trouble with mildew and wood rot. I told her she probably needed some soffits to promote air flow and that they were so easy to install I'd give her a hand. After we finished she added more insulation but later told me the soffits weren't doing their job. I was baffled. We crawled back into her attic and found that the new insulation was covering the soffits. "What you need now are some baffles to keep the soffit vents free," I told her. "Does it ever end with home repair?" she asked. I had to say no, it really doesn’t. Of course, we had to remove the new insulation to put in the baffles but now the attic is vented and her utility bills have taken a dive.
Effective insulation requires ventilation - Sufficient airflow is critical to proper roof-system ventilation. Airflow prevents heat buildup in your attic and helps protect your roof from damage caused by condensation or ice. A typical ventilation system has vents in the soffits to admit fresh air that flows upward through the baffle beneath the roof sheathing and exits through roof vents. Measure attic space to determine the number of vents per cubic foot. If there is no vapor barrier, you'll need 1 square foot of vent for every 150 square feet of attic space. You'll need 1 square foot of vent per 300 square feet of attic if there is a barrier. Either way, you'll need several vents for adequate circulation. Distribute them evenly throughout your attic.
ADD SOFFIT VENTS TO INCREASE AIRFLOW INTO ATTICS. Make sure there is an unobstructed air passage from the soffit area to the roof before you install new soffit vents. Do not cover the vents with insulation.
CONTINUOUS SOFFIT VENTS PROVIDE EVEN AIRFLOW INTO ATTICS. They are usually installed during new construction, but they can be added as retrofits to unvented soffit panels.
ROOF VENTS ARE ONE WAY TO GET AIR OUT OF THE ATTIC, and installation is fairly simple. A POWERED ROOF VENT (inset) has a thermostat-controlled fan that will increase air circulation; one of these may be all the venting your house needs.
CONTINUOUS RIDGE VENTS INCREASE AIR CIRCULATION DRAMATICALLY and are much less noticeable than traditional roof vents. Because these span the entire length of the ridge, they provide more consistent air circulation than other vents. Ridge vents are best installed during roof construction but can be retrofitted.
GABLE VENTS, LIKE ROOF VENTS, INCREASE CIRCULATION without calling attention to themselves. Because you don't need to climb on the roof to install them, they're ideal when the roof is too steep for comfort.
Installing a Soffit Vent
1 FR0M INSIDE THE ATTIC, CHOOSE AND MARK A PUCE FOR THE SOFFIT VENT THAT ALLOWS THE AIR TO FLOW FREELY. Drill through the soffit to enable you to spot the location from outside. If you're unable to get near enough to the wall because of the roof slope, locate the joists with a stud finder, as shown here, and position the vent between them.
2 TRACE AROUND THE VENT ON THE SOFFIT. Be sure the vent will fall between rafter ends or nailer strips.
SECURE YOUR LADDER - Use a secure platform (ladder or scaffolding) when working at aboveground elevations.
3 CUT THE VENT OPENINGS 1/4 INCH INSIDE THE MARKED LAYOUT LINES (or as directed) to leave room for fastening the vent covers. Use a saber saw.
4 INSTALL THE SOFFIT VENTS and fasten them with stainless-steel screws or galvanized wood screws.
Installing a Roof Vent
1 DRIVE A NAIL THROUGH THE ROOF FROM INSIDE TO MARK THE POSITION OF THE VENT HOLE. Locate roof vents as high as possible on the roof, but below the ridge tine, and on the least visible slope of the house. Place the vent between rafters to avoid cutting through a rafter. Locate turbine vents close to the ridge with a minimum clearance of 8 inches to the ridge line. Using the nail as a center point, draw a circle with a diameter equal to the vent’s opening.
2 REMOVE THE SHINGLES JUST ABOVE AND TO THE SIDE OF THE CUTOUT AREA THAT WILL BE COVERED BY THE FLANGE AT THE BASE OF THE VENT. Do not remove shingles below the vent cutout—they will be covered by the flange. Hammer the centering nail back through the roof. Drill a pilot hole with a spade bit at each corner of the cutout area; then use a reciprocating saw to cut the vent hole.
3 APPLY ROOFING CEMENT TO THE UNDERSIDE OF THE FLANGE. Slide the top edge of the flange under the shingles immediately above the hole you cut. Center the vent over the hole.
4 NAIL THE VENT IN PLACE with galvanized roofing nails. Nail the base at the top, sides, and bottom. Cover the nail holes and the seam between the base and the roof with roofing cement. Leave the bottom edge exposed.