Fiberglass Batt in Zone 7 (Very Cold)
Fiberglass Batt provides R-3.2 per inch of thickness at a material cost of $0.12 per square foot per R-value point. In Climate Zone 7 (Very Cold), with 10,000 HDD and 300 CDD, see the thickness and cost required for each building component below.
Specifications
Fiberglass Batt Requirements by Component in Zone 7
The table below shows the DOE recommended R-value, required thickness of Fiberglass Batt, material cost per square foot, and total material cost per 1,000 square feet for each building component in Climate Zone 7. Components where Fiberglass Batt is specifically recommended are highlighted. Components where insulation is not required show "N/R" (not required).
| Component | Required R | Thickness | $/SqFt | $/1000 SqFt | Fits Cavity | Rec. |
|---|---|---|---|---|---|---|
| Attic | R-60 | 18.8" | $7.20 | $7,200 | No | Yes |
| Wall Cavity | R-13 | 4.1" | $1.56 | $1,560 | No | Yes |
| Wall Continuous (Exterior) | R-10 | 3.1" | $1.20 | $1,200 | No | - |
| Floor (Over Unconditioned Space) | R-25 | 7.8" | $3.00 | $3,000 | Yes | Yes |
| Basement Wall | R-15 | 4.7" | $1.80 | $1,800 | No | - |
| Crawlspace | R-10 | 3.1" | $1.20 | $1,200 | Yes | - |
| Cathedral Ceiling | R-49 | 15.3" | $5.88 | $5,880 | No | - |
| Garage Ceiling (Below Living Space) | R-38 | 11.9" | $4.56 | $4,560 | No | Yes |
Fiberglass Batt in Zone 7 — Guidance
Fiberglass batt insulation at R-3.2 per inch is the most widely used insulation product in residential construction and a practical choice for many applications in Zone 7 (Very Cold). Batts come in pre-cut widths for standard 16-inch and 24-inch stud and joist spacing, making them straightforward to install for both professionals and DIY homeowners. In Zone 7, the R-60 attic requirement would need approximately 18.8" of fiberglass batts — multiple layers installed perpendicular to each other. While blown-in insulation is more practical for deep attic applications, fiberglass batts remain the standard for wall cavities at R-13 and floor applications at R-25. The key to achieving rated performance with fiberglass batts is installation quality. Each batt must fill the entire cavity without gaps, voids, or compression. Cut batts to fit around wiring, plumbing, and electrical boxes rather than stuffing or compressing the insulation. Faced batts with a kraft paper vapor retarder should be installed with the facing toward the warm-in-winter side of the assembly in heating-dominated climates. At $0.12 per square foot per R-value, fiberglass batts are among the most affordable insulation options available.
States in Zone 7
These states include areas within Climate Zone 7 where the Fiberglass Batt requirements shown above apply. Click any state for its complete insulation recommendations.