How Much Insulation for a 2,000 Sq Ft Attic?
Quick Answer
For a 2,000 sq ft attic targeting R-38, you need about 63 rolls of R-38 fiberglass batts or 60 to 80 bags of blown-in cellulose. Cold climates targeting R-49 need about 80 rolls.
- R-38 fiberglass batts: ~63 rolls
- R-49 fiberglass batts: ~80 rolls (cold climates)
- Blown-in cellulose (R-38): 60–80 bags
- Add 10% for irregular joist spacing and obstacles
Formula
Divide attic square footage by the coverage per roll from the packaging. For 16-inch OC joists, each R-38 roll covers about 32 sq ft.
Step-by-Step Calculation
- 1
Attic area
2,000 sq ft
- 2
R-38 batts (32 sq ft per roll)
2,000 ÷ 32 = 62.5 → 63 rolls
- 3
Blown-in cellulose
2,000 × 0.03–0.04 bags/sq ft = 60–80 bags
- 4
Add 10% waste
63 × 1.10 = 69 rolls
Insulation for 2,000 Sq Ft Attic by Type
| Insulation Type | R-Value | Depth | Quantity | Material Cost* |
|---|---|---|---|---|
| Fiberglass Batts | R-30 | ~10" | 53 rolls | $800–$1,300 |
| Fiberglass Batts | R-38 | ~12" | 63 rolls | $1,000–$1,600 |
| Fiberglass Batts | R-49 | ~16" | 80 rolls | $1,270–$2,000 |
| Blown-In Cellulose | R-38 | ~10.5" | 67 bags | $670–$1,070 |
| Blown-In Fiberglass | R-38 | ~14" | 73 bags | $870–$1,330 |
*Materials only. Professional installation adds $0.50–$1.50 per sq ft.
Frequently Asked Questions
What R-value do I need for my attic?
R-38 for climate zones 1–3 (southern US), R-49 for zones 4–5 (mid-US), and R-60 for zones 6–7 (northern US and Canada). Check the DOE climate zone map for your area.
How many bags of blown-in insulation for a 2,000 sq ft attic?
Plan on 60 to 80 bags of blown-in cellulose for R-38 over 2,000 sq ft. The exact count is printed on each bag as coverage at a target R-value, so check the label before buying.
Is it worth adding attic insulation myself?
Yes. Attic insulation is one of the highest-return DIY jobs. Many home stores lend a blower free with a bag purchase, and doing it yourself saves the $0.50–$1.50 per sq ft install cost.