Determine how much insulation you need and the estimated cost for your project.
Our insulation calculator helps you estimate how much insulation material you need and the total project cost. Proper insulation is one of the most cost-effective home improvements — it reduces energy bills, improves comfort, and can qualify for tax credits.
For example, a 1,000 sq ft attic with R-38 fiberglass insulation would cost approximately $900 for materials with DIY installation, or about $1,500 with a hired contractor.
R-value measures thermal resistance — the higher the R-value, the better the insulation. Fiberglass batts provide R-2.9 to R-3.8 per inch. Spray foam offers R-6 to R-7 per inch (highest). Cellulose provides R-3.2 to R-3.7 per inch. The Department of Energy provides climate zone maps to help you choose the right R-value for your area.
Each insulation type has different properties. Here's how they compare:
| Material | R-Value per Inch | Cost per Sq Ft (R-38) | Pros | Cons | Best For |
|---|---|---|---|---|---|
| Fiberglass Batts | 3.0-3.8 | $0.90 | Affordable, DIY-friendly, fire-resistant | Irritating to handle, gaps reduce effectiveness | Attics, walls, DIY projects |
| Spray Foam | 6.0-7.0 | $3.00 | Highest R-value per inch, air seals, moisture barrier | Expensive, professional installation required | Basements, rim joists, air sealing |
| Cellulose | 3.2-3.7 | $0.50 | Eco-friendly (recycled), good soundproofing | Can settle over time, needs blowing machine | Attics, existing wall cavities |
| Rigid Foam Board | 4.5-6.0 | $1.50 | High R-value, moisture resistant, easy to cut | Needs sealing at seams, not for irregular spaces | Basement walls, exterior sheathing |
Labor costs add approximately $0.50-$1.00 per sq ft for professional installation. Fiberglass installation is the most affordable, while spray foam requires specialized equipment and expertise.
The recommended attic insulation R-value depends on your climate zone. Most of the continental US needs R-38 to R-60. Check the DOE climate zone map: Zones 1-3 (warm) need R-30 to R-49, Zones 4-7 (cold) need R-49 to R-60. More insulation is almost always better for energy savings.
Yes, you can add insulation over existing insulation in attics, as long as the existing insulation is dry and in good condition. Never add insulation over moisture-damaged or moldy insulation. For walls, blown-in cellulose is the best option for adding insulation without removing drywall.
Proper insulation can reduce heating and cooling costs by 15-30% on average. According to the EPA, homeowners can save an average of 15% on heating and cooling costs by air sealing and adding insulation in attics, crawl spaces, and basements.
Yes, the federal government offers tax credits for qualifying insulation improvements under the Energy Efficient Home Improvement Credit. As of 2024, you can claim 30% of the cost up to $1,200 per year. Some states also offer additional rebates. Check energystar.gov for current incentives.
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