Attic Insulation Check

Start by examining your attic on a cool day. Wear a mask, gloves, and protective clothing. Check the existing insulation depth with a tape measure through the floor joists. Measure in several areas—depth may vary significantly. Identify the insulation type: fiberglass batts (pink or yellow rolls), loose-fill fiberglass (fluffy), or cellulose (gray, papery). All are effective if properly installed. Check for gaps, compressed areas, or missing sections. Look for insulation that has been disturbed by rodents or past work. Check that insulation does not block soffit vents—this is the most common attic insulation mistake. Use cardboard or foam baffles to keep insulation away from the eaves while maintaining airflow. Document the current condition with photos.

Adequate ventilation removes superheated attic air in summer. Check soffit vents from outside—they should be clear, not painted shut or covered by insulation. On the ridge, check that ridge vent is not blocked by shingles or debris. For gable vents, ensure the screen is intact. Calculate your net free vent area: you need 1 square foot of vent area per 300 square feet of attic floor area (or 1:150 for roofs with less than 2:12 slope). Half the vents should be intake (soffit) and half exhaust (ridge or gable). If you find insufficient ventilation, consider adding ridge vent, installing additional soffit vents, or adding a solar-powered attic fan. An attic fan with a thermostat activates when temperatures exceed a set point, actively exhausting hot air.

Before adding insulation, seal air leaks in the attic floor. These are the biggest source of conditioned air loss. Common leak locations: gaps around plumbing vents, electrical wiring holes, recessed light fixtures (use IC-rated covers), attic access hatches, flues and chimneys (use aluminum flashing and high-temp caulk), and where walls meet the attic floor. Seal gaps with expanding foam for small holes and caulk for cracks. Install weatherstripping around the attic hatch and cover the hatch with an insulated foam panel. Ductwork in the attic should be sealed with mastic and insulated. Air sealing before adding insulation multiplies the effectiveness of the insulation—without sealing, heat bypasses insulation through air movement.

If your attic needs more insulation, you have two options: loose-fill cellulose blown in with a rental machine or fiberglass batts laid over existing insulation. Loose-fill is easier for irregular spaces and provides better coverage. Rent a blower from a home center—many offer free rental with insulation purchase. Mark the desired depth on attic joists with chalk. Install baffles at the eaves first. Blow insulation starting farthest from the access point, working backward. Avoid covering recessed lights or exhaust fans. For batts, lay unfaced batts perpendicular to the joists on top of existing insulation. Do not compress the insulation—its R-value depends on trapped air. Never place insulation over knob-and-tube wiring (fire hazard). After installation, measure final depth in several places to confirm target R-value.