Steps // Improving Attic Ventilation
1 ×

What to look for

 
Step One // Improving Attic Ventilation

What to look for

using a chalk reel to snap two parallel lines down the center of the soffit
Photo by Merle Henkenius

Soffit vents come in several sizes and styles, including small round discs and rectangular grilles. We opted for aluminum strip vents that measure 3 in. wide x 8 ft. long. This style vent provides a quick way to ventilate every rafter bay. Strips vents come in white, brown and silver; you'll pay less than $3 for an 8-ft. length.

Mark two parallel lines
Start by using a chalk reel to snap two parallel lines down the center of the soffit. Space the lines 2 in. apart; that will allow the vent to overlap the cutout by ½ in. on each edge.

 
2 ×

Cut parallel lines

 
Step Two // Improving Attic Ventilation

Cut parallel lines

cutting the two parallel lines with a portable circular saw
Photo by Merle Henkenius

Next, bore a 3⁄4- or 1-in.-dia. 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.

 
3 ×

Connect the two cuts

 
Step Three // Improving Attic Ventilation

Connect the two cuts

connecting the two cuts with a sharp chisel
Photo by Merle Henkenius

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.

 
4 ×

Raise the vent up to the soffit

 
Step Four // Improving Attic Ventilation

Raise the vent up to the soffit

raising the vent up to the soffit and center it over the cutout slot
Photo by Merle Henkenius

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-in.-dia. 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.

 
5 ×

Attach the vent to the soffit

 
Step Five // Improving Attic Ventilation

Attach the vent to the soffit

using a cordless drill/driver to secure the vent to the soffit
Photo by Merle Henkenius

Use a cordless drill/driver to secure the vent to the soffit with ½-in.-long 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.

 
6 ×

Remove any insulation from the new vent

 
Step Six // Improving Attic Ventilation

Remove any insulation from the new vent

raking back blown-in insulation from the new soffit vent
Photo by Merle Henkenius

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-ft.-long 1 x 6, or use a garden rake or hoe.

 
7 ×

Install the ventilation baffle

 
Step Seven // Improving Attic Ventilation

Install the ventilation baffle

stapling a ventilation baffle to the plywood sheathing
Photo by Merle Henkenius

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.

 
 

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