Types of Insulation: Complete Comparison Guide (2026)
Compare fiberglass, cellulose, spray foam, and other insulation types to choose the best option for your home, budget, and project.
Quick Comparison
| Type | R-Value/Inch | Cost/Sq Ft | Best Use |
|---|---|---|---|
| Fiberglass Batts | R-3.2 | $0.40-0.60 | DIY, walls |
| Blown Fiberglass | R-2.5-3.0 | $1.50-2.00 | Attics |
| Blown Cellulose | R-3.5-3.8 | $1.30-1.50 | Attics, walls |
| Spray Foam (Open) | R-3.5-4.0 | $1.00-1.50 | Air sealing |
| Spray Foam (Closed) | R-6.0-7.0 | $3.00-4.00 | Roofs, foundations |
| Rigid Foam Boards | R-4.0-6.5 | $0.50-1.50 | Basements, exterior |
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1. Fiberglass Batts (Rolls)
Pre-cut rolls of pink or yellow fiberglass. The most common DIY insulation found at home improvement stores.
Description
Fiberglass batts are blankets of woven glass fibers that trap air to slow heat transfer. They come in standard widths (15" or 23") to fit between studs and joists. Available in various thicknesses for different R-values (R-11, R-13, R-19, R-30, R-38).
Pros & Cons
Advantages
- Cheapest option ($0.40-0.60/sq ft materials)
- Easy DIY installation - no special equipment
- Widely available at big-box stores
- Fire-resistant and won't settle over time
- Good for standard 2x4 or 2x6 walls
Disadvantages
- •Leaves gaps around obstacles (wiring, pipes, boxes)
- •Labor-intensive to install properly
- •Itchy to work with (requires protective gear)
- •Compression reduces R-value significantly
- •Not ideal for attics (blown is better)
Best For
- DIY projects - walls, floors, accessible attics
- New construction or renovations with open walls
- Budget-conscious homeowners willing to do the work
- Basements and crawlspaces (between joists)
2. Blown Fiberglass (Loose-Fill)
Fluffy fiberglass blown into attics with a machine. Fills gaps better than batts and is the most popular professional attic insulation.
Description
Blown fiberglass uses the same material as batts but in loose form. A blowing machine breaks up the fiberglass and shoots it through a hose, filling attics evenly. The fluffy texture fills gaps around obstacles and creates uniform coverage.
Pros & Cons
Advantages
- Fills gaps and irregular spaces perfectly
- Fast professional installation (4-6 hours)
- Won't settle or compress over time
- Fire-resistant and pest-resistant
- Can be added over existing insulation
Disadvantages
- •More expensive than batts ($1.50-2.00/sq ft)
- •Requires professional equipment (blower)
- •Lower R-value per inch than cellulose
- •Can shift if disturbed (walking in attic)
Best For
- Attic floors - #1 most popular choice
- Homeowners who want professional installation
- Topping up existing insulation
- Irregular attic spaces with many obstacles
3. Blown Cellulose
Made from recycled newspapers treated with fire retardant. Eco-friendly, excellent R-value, and often the most affordable blown option.
Description
Cellulose is shredded recycled paper (mostly newspapers) treated with borate for fire and pest resistance. It's denser than fiberglass, providing better soundproofing and slightly higher R-value per inch. Blown into attics or dense-packed into walls.
Pros & Cons
Advantages
- Cheapest blown option ($1.30-1.50/sq ft)
- Highest R-value per inch of blown insulation
- 85% recycled content - very eco-friendly
- Better soundproofing than fiberglass
- Can be dense-packed into existing walls
Disadvantages
- •Settles 10-20% over 10-20 years (reduces R-value)
- •Can mold if exposed to moisture
- •Heavier than fiberglass (stress on ceiling)
- •Messier installation (more dust)
Best For
- Attics - best value for R-value per dollar
- Eco-conscious homeowners (recycled content)
- Soundproofing projects (denser = better sound blocking)
- Dense-pack wall insulation (existing homes)
4. Spray Foam Insulation
Spray foam comes in two types: open-cell (lower R-value, vapor permeable) and closed-cell (highest R-value, moisture barrier). Both expand on contact to fill gaps and air seal simultaneously.
Open-Cell Spray Foam
- Softer, spongy texture
- Good air sealing + insulation
- Best for interior applications
- Vapor permeable (breathes)
Closed-Cell Spray Foam
- Dense, rigid structure
- Highest R-value available
- Acts as moisture barrier
- Best for roofs, foundations
When to Choose Spray Foam
- Low-clearance attics where you need max R-value in minimal space
- Rim joists and band boards (open-cell works great here)
- Cathedral ceilings without attic access
- When you want air sealing + insulation in one application
- Basements and crawlspaces prone to moisture (closed-cell)
Reality check: Spray foam costs 2-3x more than blown cellulose or fiberglass for standard attics. Most homes don't need it. Save spray foam for specific applications where its unique properties (air sealing, moisture barrier, high R-value per inch) justify the cost.
Which Insulation Type Should You Choose?
Choose Blown Cellulose if...
- You want the best value (highest R-value per dollar)
- You care about eco-friendliness (85% recycled)
- You're insulating an attic (most popular choice)
Choose Blown Fiberglass if...
- You want zero settling over time
- You're in a humid climate (no mold risk)
- Professional install is slightly more available in your area
Choose Fiberglass Batts if...
- You're doing DIY in walls or floors
- You have an extremely tight budget
- You have open stud walls (renovation/new construction)
Choose Spray Foam if...
- You have low-clearance attic (<4 ft) needing max R-value
- You want air sealing + insulation in one step
- Budget isn't a concern (2-3x more expensive)