What does proper attic insulation and venting look like, from ridge to ceiling?
Short answer. From the top down, a properly built vented attic has ridge or high exhaust, a dry deck with at least 1 inch of clear air space at the eaves, baffles over every soffit bay, open soffit intake, insulation at roughly R-38 to R-49 on the attic floor for most of Georgia, and an air sealed ceiling and hatch below it. Each layer depends on the one beside it.
Top to bottom
- Exhaust: a ridge vent with an open slot, or box vents within 3 feet of the ridge, one type only.
- Deck: dry, firm sheathing with bright nail tips.
- Air channel: at least 1 inch between insulation and the deck at the eaves, held open by baffles.
- Intake: vented soffit or edge vents equal to or greater than the exhaust.
- Insulation: an even layer on the attic floor. ENERGY STAR's retrofit table for climate zone 3, most of Georgia, points to about R-49 for an uninsulated attic, with higher targets in the colder mountain counties.
- Air barrier: the ceiling sealed at top plates, wiring and plumbing holes, chases, recessed lights and the hatch.
- Ducts: sealed and insulated if they run through the attic.
- Exhaust fans: ducted outdoors, never into the attic.
Common conflicts
- Blown insulation spilling into soffit vents when baffles or dams are missing.
- Insulation piled against the deck at the eaves.
- Insulation added before air sealing, burying the leaks.
- Storage platforms crushing insulation.
Retrofit order
Fix roof leaks, air seal, install baffles, then add insulation, and adjust vents last. Doing it in the wrong order means undoing work. See roof ventilation basics and attic heat and shingles.