Understanding R-Value
R-value measures insulation's resistance to heat flow. Higher R-values indicate better insulating power. The recommended R-value depends on your climate zone, the part of your home being insulated, and local building codes.
Recommended R-Values by Zone
| Location | Hot (1-2) | Mixed (3-4) | Cold (5-6) | Very Cold (7-8) |
|---|---|---|---|---|
| Attic | R-30 to R-49 | R-38 to R-60 | R-49 to R-60 | R-49 to R-60 |
| Walls | R-13 to R-15 | R-13 to R-21 | R-13 to R-21 | R-13 to R-21 |
| Floor | R-13 | R-19 to R-25 | R-25 to R-30 | R-25 to R-30 |
| Basement | R-11 to R-13 | R-11 to R-15 | R-11 to R-19 | R-15 to R-19 |
Insulation Types Comparison
| Type | R per Inch | Cost/Sq Ft | Best For |
|---|---|---|---|
| Fiberglass Batts | R-2.9 to R-3.8 | $0.30-0.50 | Standard walls, DIY |
| Mineral Wool | R-3.0 to R-4.2 | $0.60-1.00 | Fire resistance, sound |
| Blown Fiberglass | R-2.2 to R-2.7 | $0.40-0.80 | Attics, retrofits |
| Blown Cellulose | R-3.2 to R-3.8 | $0.35-0.70 | Attics, eco-friendly |
| Open Cell Foam | R-3.5 to R-3.7 | $1.00-1.50 | Air sealing, walls |
| Closed Cell Foam | R-6.0 to R-7.0 | $2.00-3.00 | Maximum R-value, vapor barrier |
Installation Tips
- Always wear protective gear: mask, goggles, gloves, long sleeves
- Never compress batts - full thickness provides rated R-value
- Cut batts to fit snugly around wiring and pipes
- Face vapor barrier toward the warm-in-winter side
- Seal air leaks before adding insulation for maximum efficiency
- Ensure proper attic ventilation with any insulation type
- Check local codes for required R-values and installation methods
Signs You Need More Insulation
- Uneven temperatures between rooms
- High heating/cooling bills
- Ice dams on roof in winter
- Cold walls or floors
- HVAC runs constantly
- Attic insulation below 10-12 inches