Attic Insulation in Zone 6 (Cold)
The DOE recommends R-60 for attic insulation in Climate Zone 6 (Cold). This zone has 8,000 heating degree days and 500 cooling degree days annually. The typical attic cavity depth is 16 inches. States in Zone 6 include Colorado, Connecticut, Idaho, Iowa, Maine and 14 more.
Quick Facts
Insulation Comparison for Attic in Zone 6
The table below compares all insulation types for achieving R-60 in the attic of a building in Zone 6 (Cold). Types marked "Recommended" are specifically suited for attic applications. Material costs are shown per square foot and per 1,000 square feet for easy budgeting. Labor costs typically add 30 to 100 percent to material costs depending on the insulation type and project complexity.
| Insulation Type | R/Inch | Thickness | $/SqFt | $/1000 SqFt | Fits | Rec. |
|---|---|---|---|---|---|---|
| Blown-In Cellulose | R-3.5 | 17.1" | $4.20 | $4,200 | No | Yes |
| Blown-In Fiberglass | R-2.5 | 24" | $4.80 | $4,800 | No | Yes |
| Vermiculite (Loose Fill) | R-2.1 | 28.6" | $6.00 | $6,000 | No | Yes |
| Fiberglass Batt | R-3.2 | 18.8" | $7.20 | $7,200 | No | Yes |
| Expanded Polystyrene (EPS) | R-3.9 | 15.4" | $7.20 | $7,200 | Yes | Yes |
| Mineral Wool Batt | R-3.3 | 18.2" | $9.00 | $9,000 | No | Yes |
| Cotton Denim (Recycled) | R-3.5 | 17.1" | $12.00 | $12,000 | No | Yes |
| Polyisocyanurate (Polyiso) | R-6 | 10" | $13.20 | $13,200 | Yes | Yes |
| Sheep Wool | R-3.5 | 17.1" | $21.00 | $21,000 | No | Yes |
| Extruded Polystyrene (XPS) | R-5 | 12" | $10.80 | $10,800 | Yes | - |
| Mineral Wool Board | R-4.3 | 14" | $15.00 | $15,000 | Yes | - |
| Open-Cell Spray Foam | R-3.7 | 16.2" | $24.00 | $24,000 | No | - |
| Closed-Cell Spray Foam | R-6.5 | 9.2" | $48.00 | $48,000 | Yes | - |
| Aerogel Blanket | R-10 | 6" | $180.00 | $180,000 | Yes | - |
Installation Guidance
In Climate Zone 6, achieving R-60 in the attic requires a substantial depth of insulation — typically 17 to 24 inches of blown-in material. Before adding insulation, conduct thorough air sealing of all penetrations through the attic floor. Seal around electrical boxes, plumbing vents, HVAC duct connections, recessed light housings, and the top plates of interior partition walls using fire-rated caulk, spray foam, or metal flashing as appropriate. Install ventilation baffles at every rafter bay along the eaves to maintain airflow from soffit vents to ridge vents. The weight of deep insulation can be a concern — cellulose at R-60 weighs approximately 2.5 pounds per square foot. Verify that ceiling framing and fasteners can support this load. In extremely cold zones, consider adding a continuous layer of rigid foam insulation on top of the attic floor joists before blowing in loose fill to reduce thermal bridging through the framing.
States in Zone 6
The following states include areas within Climate Zone 6. Click any state to see its complete insulation requirements across all applicable zones.