The complete reference — every R-value for every application and climate zone, with product recommendations.
R-value measures thermal resistance — the higher the number, the better the insulation. The right R-value for your project depends on climate zone, assembly type, and framing depth. Here's the full chart.
| Framing | Product | R-Value | Zones | Notes |
|---|---|---|---|---|
| 2×4 | Fiberglass standard | R-13 | 1–3 | Code minimum zones 1–3 |
| 2×4 | Fiberglass HD | R-15 | 4–8 | Required for zones 4+ under IECC 2021 |
| 2×6 | Fiberglass standard | R-19 | 1–4 | Common in mild climates |
| 2×6 | Fiberglass HD | R-21 | 4–8 | Best performance in standard 2×6 cavity |
| 2×4 or 2×6 | Mineral wool AFB | R-15 or R-23 | All | Fire-rated / high-STC assemblies |
| Climate Zone | States (examples) | Minimum | Recommended |
|---|---|---|---|
| Zone 1 | Hawaii, South Florida | R-30 | R-30 |
| Zone 2 | Gulf Coast TX/LA/FL | R-30 | R-30 to R-38 |
| Zone 3 | Southeast, CA coast | R-38 | R-38 |
| Zone 4 | Mid-Atlantic, Pacific NW | R-38 | R-49 |
| Zone 5 | Midwest, New England | R-49 | R-49 |
| Zone 6 | Minnesota, Montana, upstate NY | R-49 | R-49 to R-60 |
| Zone 7–8 | Alaska, northern MN/MT/ND | R-49 | R-60 |
| Climate Zone | Floor / Crawl Space | Basement Wall |
|---|---|---|
| Zone 1–2 | R-13 | Not required |
| Zone 3 | R-19 | R-5 continuous |
| Zone 4 | R-19 | R-10 continuous or R-13 cavity |
| Zone 5–6 | R-30 | R-15 continuous or R-19 cavity |
| Zone 7–8 | R-38 | R-15 continuous or R-19 cavity |
| Product | R-Value | Thickness | Best For |
|---|---|---|---|
| R-11 | R-11 | 3.5" | Interior partitions, sound control, retrofit floors |
| R-13 | R-13 | 3.5" | 2×4 exterior walls, zones 1–3 |
| R-15 HD | R-15 | 3.5" | 2×4 exterior walls, zones 4–8 |
| R-19 | R-19 | 6.25" | 2×6 walls, crawl space floors, floor joists |
| R-21 HD | R-21 | 5.5" | 2×6 exterior walls, zones 4–8 |
| R-30 | R-30 | 9.5–10" | Attic floors, zones 1–3 |
| R-38 | R-38 | 12" | Attic floors, zones 3–5 |
| R-49 | R-49 | 16" | Attic floors, zones 5–8 |
| Mineral Wool AFB | R-15 | 3.5" | Fire-rated, high-STC assemblies |
Use our free bag calculator to convert square footage to bag quantity for any R-value. Or call (929) 466-1426 — we'll confirm the right product and quote same-day.
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