Improving Attic Ventilation Installing soffit vents By Merle Henkenius of Today’s HomeownerReed Herman
Cut parallel lines
Next, bore a 3⁄4- or 1. hole through the soffit right between the lines and measure the thickness of the soffit panel (probably 1⁄4 or 3⁄8 in.). Then set your circular saw to that depth and cut along the chalk lines.
Cut the two parallel lines with a portable circular saw. Set the blade depth to barely cut through the thin soffit material.
Connect the two cuts
When you near the end of the soffit, stop short and connect the two cuts with a sharp chisel or sabre saw. Once all cuts are made, use a thin pry bar to remove the 2-in. plywood strip. Pull any nails that remain in the soffit framing with a cat’s paw.
Then inspect the length of the vent cutout. If there’s any insulation clogging the slot, pull it out or shove it back up.
Raise the vent up to the soffit
Next, lay the strip vent down on a flat wood surface, such as a plywood sheet or long 2 x 4, and drill 1⁄8. screw holes through both flanges. Space the holes 12 to 14 in. apart. With the help of an assistant, raise the vent up to the soffit and center it over the cutout slot.
Attach the vent to the soffit
Use a cordless drill/driver to secure the vent to the soffit with ½- No. 4 sheet-metal screws. Continue installing additional strip vents until you reach the far end. Trim the last vent to length using aviation snips.
Remove any insulation from the new vent
The soffit vents are now installed, but you still need to make sure there’s no insulation blocking the new vents. If the attic is insulated with fiberglass batts, just pull back any that are blocking the flow of air. If there’s blown-in insulation, like ours, rake back the fluffy stuff with a 3- or 4 1 x 6, or use a garden rake or hoe.
Install the ventilation baffle
Finally, to ensure that the airway to the vent remains open, staple a ventilation baffle to the plywood sheathing in each rafter bay. The molded polystyrene baffles, available at home centers and lumberyards for about $1 each, form channels that hold insulation at bay and direct incoming air upward.