Homeowner Tips
Your Attic Insulation Is a Roofing Problem
Insulation, ventilation and air sealing work as one system. Get one wrong and your roof pays for it in shortened shingle life and higher bills.
By Taylor Smith · · 6 min read
Homeowners think of the attic as storage. Your roof thinks of it as a climate.
Three jobs, one system
Air sealing stops conditioned air leaking up. Insulation slows heat transfer. Ventilation flushes the heat and moisture that get through anyway. Fix insulation without ventilation and you trap moisture; add ventilation without air sealing and you pull conditioned air out of the house.
The blocked-soffit problem
The most common defect we find: blown-in insulation pushed out to the eaves, burying the soffit vents. Intake air stops, ridge vents pull from the house instead of the soffits, and the deck runs 15–20 degrees hotter. Baffles at each rafter bay fix it in an afternoon.
What to look for
- Rusty nail tips on the underside of the deck — condensation.
- Dark staining on the sheathing — chronic moisture.
- Insulation depth below about 14 inches — under-insulated for this climate.
- Bath fans venting into the attic instead of through the roof.
Do this during a re-roof
Tear-off is the one time the deck is exposed and vents are easy to add or relocate. Doing ventilation work later costs multiples of doing it that week.
