How do you stop insulation from blocking soffit vents?

How the blockage happens

Blown cellulose and fiberglass flow almost like snow. When insulation is blown toward the eaves without baffles, it fills the tight space where the roof meets the wall and packs against the back of the soffit. From outside, the soffit vents look fine. From inside, no air gets through. Adding insulation to an older home without adding baffles is one of the most common ways a working attic becomes a poorly vented one.

Signs your vents are blocked

• No daylight visible at the eaves from inside the attic on a sunny day.
• Insulation packed against the underside of the deck along the walls.
• Mildew or darkened decking along the lower edge of the roof.
• A ridge vent that leaks or whistles in storms, because it is pulling air from wherever it can.

The fix

1. Rake the insulation back from the eave in each bay.
2. Staple a baffle to the underside of the deck in each bay, running from the top of the wall plate up past the finished insulation depth.
3. Add a block or dam at the wall plate if the baffle style calls for one, so insulation cannot drift down into the soffit.
4. Put the insulation back, full depth, right up to the baffle.

Baffles also let you keep full insulation depth over the exterior walls, where Georgia homes tend to lose heat in winter and gain it in summer. The work is cramped and itchy and done on your knees at the shallowest part of the attic, so many homeowners hire it out, often along with an insulation top-up. See roof ventilation basics and attic heat and shingles.