7 Types of Home Insulation: Complete Comparison Guide (2026)

Quick Answer: The seven main types of home insulation are fiberglass, cellulose, mineral wool, spray foam (open-cell and closed-cell), rigid foam board (EPS, XPS, polyiso), radiant barriers, and natural/eco materials. Fiberglass remains the most widely installed at $0.30–$1.50/sq ft. Spray foam delivers the highest R-value per inch (up to R-7.0) but costs 3–5× more. The best type depends on where you're insulating, your climate zone, your budget, and whether you need fire resistance, moisture control, or soundproofing.

Table of Contents

• Master Comparison Table
• 1. Fiberglass Insulation
• 2. Cellulose Insulation
• 3. Mineral Wool / Rockwool
• 4. Spray Foam Insulation
• 5. Rigid Foam Board Insulation
• 6. Radiant Barriers
• 7. Natural & Eco-Friendly Insulation
• Which Type Is Best For Your Application
• Cost Comparison
• How to Choose: The 5 Factors
• Common Mistakes
• Key Takeaways
• FAQ

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Master Comparison Table

Rigid foam costs are material-only. R-value data sourced from DOE insulation fact sheets and manufacturer specifications. See our R-value insulation chart for complete R-value data and insulation cost calculator for project pricing.

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1. Fiberglass Insulation

Fiberglass accounts for roughly 60% of all insulation installed in US homes. It comes in two forms: batts (pre-cut blankets) and blown-in (loose-fill).

Batts are manufactured in standard widths (15" for 16" OC framing, 23" for 24" OC) and come in specific R-values matched to cavity depths. Common products include R-11 and R-13 (3.5" thick for 2×4 walls), R-15 high-density (also 3.5"), R-19 (6.25" for 2×6 walls), R-21 high-density (5.5" for 2×6), and R-30/R-38/R-49 for attics and floors. Faced batts have a kraft paper or foil vapor retarder on one side; unfaced batts don't.

Blown-in fiberglass is machine-blown into attics and wall cavities. In attic applications, it delivers R-2.2 to R-2.7 per inch — the lowest R-per-inch on the chart — but that's offset by installing it thick. At 18–20 inches, blown-in fiberglass hits R-44 to R-49.

Pros: Cheapest insulation on the market ($0.30–$1.50/sq ft installed). Widely available everywhere. Non-combustible (won't burn, though it melts at 1,300–1,500°F). DIY-friendly in batt form. Won't rot or support mold growth.

Cons: Very sensitive to installation quality — gaps, compression, and voids are the #1 performance killer. RESNET Grade III installation (common) drops real-world performance by 30%+. Doesn't air seal. Absorbs and holds moisture, losing significant R-value when wet. Susceptible to wind washing in exposed locations. Batts are essentially useless around irregular obstructions (wiring, plumbing, electrical boxes) unless meticulously cut and fitted.

Cost: $0.30–$1.50/sq ft (batts, installed) | $0.50–$2.00/sq ft (blown-in, installed)

For the complete breakdown, see our fiberglass insulation guide.

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2. Cellulose Insulation

Cellulose is made from approximately 80% recycled newspaper treated with borate fire retardants. It comes in two forms: loose-fill (blown into open attics) and dense-pack (blown under pressure into enclosed cavities).

Loose-fill cellulose at R-3.2 to R-3.8 per inch is one of the most cost-effective options for attic floors. It flows around obstructions better than batts, which typically means better coverage around wiring, plumbing, and ductwork. The installed cost of $0.60–$2.30/sq ft makes it competitive with blown-in fiberglass.

Dense-pack cellulose at R-3.5 to R-3.8 per inch and 3.5 lbs/cu ft density is the gold standard for retrofitting existing walls. An installer drills 2–3 inch holes through the siding or interior plaster, inserts a fill tube, and blows cellulose under pressure until the cavity is completely packed. The high density resists settling and provides modest air-sealing properties — not a full air barrier, but meaningfully better than batts.

Pros: High recycled content (80%+). Excellent coverage around obstructions. Dense-pack provides good air-sealing properties. Borate treatment resists fire, mold, and pests. Most cost-effective wall retrofit option.

Cons: Settles approximately 20% in the first few years when loose-filled — install 20% deeper to compensate. Absorbs moisture (though borate treatment helps it resist mold). Heavier than fiberglass — can cause ceiling sag if over-applied on older drywall without adequate support. Requires blowing machine (DIY possible for attic loose-fill, but dense-pack needs professional equipment and training). Flame spread rating of ≤25, but smoke development index reaches 450.

Cost: $0.60–$2.30/sq ft (loose-fill, installed) | $1.50–$3.00/sq ft (dense-pack, installed)

Full guide: cellulose insulation. Compare head-to-head: fiberglass vs. cellulose.

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3. Mineral Wool / Rockwool

Mineral wool (often sold under the brand name Rockwool) is made from basalt rock and recycled slag spun into fibers. It delivers R-3.8 to R-4.3 per inch — with Rockwool's Comfortbatt averaging about R-4.2/inch. It's available as batts, rigid boards (Comfortboard), and loose-fill.

This is the material we reach for when a project needs fire resistance, sound control, or moisture management beyond what fiberglass offers.

Fire performance is mineral wool's headline advantage. It's rated to withstand temperatures above 2,150°F — compared to fiberglass that melts at 1,300–1,500°F. Flame spread index of 0 and smoke development index of 0. It's the only common insulation that's truly non-combustible. Rockwool's fire resistance testing data documents performance in standard fire wall assemblies. For fire-rated wall and floor assemblies, it's the default choice. See our insulation fire safety guide for the full comparison.

Sound performance is equally impressive. NRC (Noise Reduction Coefficient) of 1.00–1.05 for 3.5-inch batts — the highest of any standard insulation. Fiberglass is good at 0.85–0.95, but mineral wool is measurably better. For soundproofing between shared walls, floors, or around home theaters, mineral wool is our first recommendation.

Moisture handling is another strong point. Mineral wool is hydrophobic — water beads off it rather than being absorbed. If it does get wet, it dries quickly and retains its R-value. This makes it excellent for exterior applications and areas prone to occasional moisture.

Pros: Non-combustible (2,150°F+). Best sound performance of any standard insulation. Hydrophobic. Denser and more rigid than fiberglass, so it holds its shape in cavities without sagging. Higher R-per-inch than standard fiberglass. DIY-friendly.

Cons: Costs 40–70% more than fiberglass ($1.00–$2.10/sq ft vs. $0.30–$1.50/sq ft). Stiffer and denser, which makes it harder to cut and fit around obstructions. Heavier to work with. More limited product availability in some regions.

Cost: $1.00–$2.10/sq ft (installed)

Full guide: mineral wool insulation. Compare: fiberglass vs. mineral wool.

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4. Spray Foam Insulation

Spray foam is a two-component liquid that expands on contact and cures into a solid foam. It comes in two types with very different properties, costs, and applications.

Open-Cell Spray Foam

Open-cell foam expands roughly 100× its liquid volume, filling cavities completely. It delivers R-3.5 to R-3.8 per inch — similar to cellulose — and costs $1.00–$3.50/sq ft installed.

Its primary advantage is creating an air barrier while insulating. Open-cell foam is soft and flexible, making it forgiving on wood framing that expands and contracts. We use it most on attic rooflines (underside of the roof deck) when creating a conditioned attic, and in cathedral ceilings where access for blown-in materials is limited.

The downside: open-cell foam absorbs moisture. It's vapor-permeable (roughly 10 perms at 3.5 inches), which means it allows moisture to pass through — a feature in some assemblies, a liability in others. It must not be used below grade or in perpetually wet locations. See our open-cell spray foam guide for vapor management details.

Closed-Cell Spray Foam

Closed-cell foam is denser, stronger, and delivers R-6.0 to R-7.0 per inch — the highest of any common insulation material. At 2+ inches, it acts as both an air barrier and a Class II vapor retarder (<1.0 perm). It costs $1.50–$5.00/sq ft installed.

Closed-cell spray foam adds structural rigidity — it increases wall racking strength by up to 300% (manufacturer data). We use it in basements (directly on concrete walls), crawl spaces, rim joists, and any application where you need maximum R-value in minimum depth. In a 2×4 wall, 3.5 inches of closed-cell foam delivers R-21 to R-24.5 — roughly double what fiberglass provides in the same space.

The downsides are real: closed-cell spray foam costs 3–5× more than fiberglass and 2–3× more than cellulose for equivalent total R-value in open spaces. It uses hydrofluorocarbon (HFC) or hydrofluoroolefin (HFO) blowing agents — older HFC formulations have high global warming potential, though newer HFO-blown products are much better. Installation requires certified professionals with specialized equipment.

Cost: $1.00–$3.50/sq ft (open-cell) | $1.50–$5.00/sq ft (closed-cell)

Full guides: spray foam insulation, open-cell vs. closed-cell comparison, spray foam cost guide.

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5. Rigid Foam Board Insulation

Rigid foam boards are manufactured in 4×8 foot sheets (and other sizes) at various thicknesses from ½ inch to 4+ inches. Three types dominate the market:

EPS (Expanded Polystyrene) — R-3.6 to R-4.4 per inch. The most temperature-stable rigid foam and the most affordable ($0.35–$0.90/sq ft material). It's widely used for ICFs (insulated concrete forms), EIFS (exterior insulation finish systems), and below-grade applications. EPS absorbs some moisture over time, so it's usually used with drainage considerations in below-grade installations. EPS guide.

XPS (Extruded Polystyrene) — R-4.5 to R-5.0 per inch. Recognizable by its blue (Dow), pink (Owens Corning), or green (Kingspan) color. XPS is the standard for below-grade and high-moisture applications because of its low moisture absorption. It performs slightly better in cold temperatures. Long-term R-value settles closer to R-4.5 as blowing agents dissipate. Higher environmental impact than EPS due to blowing agents. XPS guide.

Polyisocyanurate (Polyiso) — R-5.6 to R-6.5 per inch (at 75°F). The highest R-per-inch of any rigid foam and the go-to for exterior continuous insulation on walls and commercial roofing. The critical caveat: polyiso's R-value drops to R-3.5–R-4.5 per inch when mean temperature falls below 25°F. Building Science Corporation's rigid foam research documents this temperature derating extensively. In cold climates (zones 5+), derate by 15–25% or layer with EPS/XPS. Polyiso guide.

Common applications for all rigid foam types: Continuous exterior insulation over wall sheathing (to reduce thermal bridging), basement and foundation walls, under-slab insulation, cathedral ceiling insulation above the roof deck, and as insulating sheathing in new construction.

Cost: $0.35–$1.50/sq ft (material) + $0.50–$1.50/sq ft (installation, varies by application)

Full guide: rigid foam board insulation.

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6. Radiant Barriers

Radiant barriers are fundamentally different from the insulation types above. They don't have an R-value — instead, they reflect radiant heat, primarily from the sun heating your roof.

A radiant barrier is a reflective material (usually aluminum foil laminated to kraft paper, OSB, or plastic) installed in the attic, typically on the underside of the roof rafters. It reflects up to 97% of radiant heat that would otherwise radiate from the hot roof deck down into the attic insulation.

Where they work: Hot, sunny climates — primarily climate zones 1 through 3 (the Deep South, Southwest, Florida, Hawaii). DOE research shows radiant barriers can reduce cooling costs by 5–10% in hot climates when installed over existing attic insulation.

Where they don't work: Cold climates. Radiant barriers address heat gain from solar radiation. In zones 5+, the heating season dominates your energy bill, and radiant barriers provide negligible benefit during heating months. Your money is better spent on more insulation or air sealing.

Limitations: A radiant barrier does nothing for conductive or convective heat loss. It's a supplement to insulation, not a replacement. Any vendor claiming a radiant barrier replaces conventional insulation is misleading you. Dust accumulation on the reflective surface reduces performance over time.

Cost: $0.15–$0.75/sq ft (installed)

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7. Natural & Eco-Friendly Insulation

A growing niche of insulation products caters to homeowners prioritizing sustainability, indoor air quality, or specific environmental certifications.

Sheep's wool delivers R-3.5 to R-3.8 per inch with natural moisture-buffering properties — it can absorb up to 35% of its weight in moisture and release it without losing R-value. It's naturally fire-resistant and provides decent sound absorption. Cost is high: $2.00–$4.00+/sq ft.

Recycled denim (cotton) batts deliver about R-3.5 per inch. They're made from post-industrial recycled cotton and polyester, treated with borate for fire and pest resistance. Easier to handle than fiberglass (no skin irritation). Similar cost premium to sheep's wool.

Cork insulation boards deliver R-3.6 to R-4.0 per inch with excellent moisture resistance and sound absorption. Cork is naturally fire-resistant, mold-resistant, and pest-resistant. It's a premium product used primarily in high-end green building projects.

These materials work well but cost 2–5× more than conventional alternatives with comparable R-values. They're best suited for projects where environmental impact, indoor air quality, or specific building certifications (LEED, Passive House) are primary goals.

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Which Type Is Best For Your Application

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Cost Comparison

All materials side by side, 2025–2026 national averages, professionally installed:

For project-specific estimates, use our insulation cost calculator or see application-specific guides: attic insulation cost, spray foam cost.

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How to Choose: The 5 Factors

1. R-Value Requirements

Start with the end goal. What total R-value does your climate zone and the 2021 IECC require for the assembly you're insulating? Energy Star's Seal and Insulate guide provides simplified recommendations by ZIP code. Reference our R-value chart for code requirements by zone, then work backward to select a material that achieves the target R-value in your available depth. Our R-value per inch chart ranks every material by thermal performance per inch.

2. Budget

Fiberglass and cellulose deliver the most R-value per dollar. If you're insulating a 1,500 sq ft attic floor to R-49, blown-in cellulose runs $900–$3,450 installed. Closed-cell spray foam to the same R-value (7–8 inches) costs $2,250–$7,500 for the same area. That's a 2.5–4× difference. Spray foam makes sense in tight spaces and where air sealing is critical, but blowing money on spray foam in an open attic rarely pencils out. Check our insulation cost calculator for real numbers.

3. Moisture Environment

Basements and crawl spaces need moisture-tolerant materials. Closed-cell spray foam (acts as its own vapor barrier at 2+ inches), XPS, and EPS are the right choices below grade. Fiberglass absorbs water and loses R-value — we've pulled wet fiberglass batts out of hundreds of crawl spaces. Mineral wool is hydrophobic but doesn't provide a vapor barrier. Always pair your insulation choice with an appropriate vapor barrier strategy.

4. Available Space

Unlimited depth (open attic floor): use the cheapest material — blown-in cellulose or fiberglass. Fixed cavity (existing 2×4 or 2×6 wall): you need higher R-per-inch materials to maximize performance. Extremely limited space (rim joists, thin wall assemblies): closed-cell spray foam's R-6.5/inch is the only way to get meaningful R-value.

5. DIY vs. Professional

Fiberglass batts, mineral wool batts, and rigid foam boards are all DIY-installable with basic tools. Blown-in loose-fill cellulose is DIY-feasible (big box stores rent blowing machines), but getting consistent coverage and proper depth requires practice. Dense-pack cellulose and all spray foam types require professional installation — the equipment, training, and quality control are beyond what DIY delivers safely or effectively.

Pro Tip: The single best insulation project for most homeowners is air sealing + blown-in insulation in the attic. It has the shortest payback period (2–5 years), the highest energy savings potential (15–25% reduction in heating/cooling costs per the DOE), and it's a relatively straightforward job. Focus there first before moving to walls or other assemblies.

Pro Tip: Don't mix vapor barriers within an assembly. If you're adding blown-in insulation on top of existing faced fiberglass batts in the attic, slash the facing on the existing batts or remove it entirely. A vapor retarder in the middle of the insulation stack traps moisture.

Pro Tip: Consider using two different insulation types in the same wall. We call this a "hybrid" assembly — for example, 2 inches of closed-cell spray foam on the back of the sheathing (for air sealing and vapor control) topped with fiberglass batt to fill the remaining cavity. This gives you the air sealing benefits of spray foam at 40–60% of the cost of a full spray foam fill. Common in zone 5+ wall assemblies.

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Common Mistakes

1. Choosing based on R-per-inch alone. A homeowner insulating a 1,500 sq ft open attic doesn't need R-7/inch closed-cell spray foam at $1.50–$5.00/sq ft when 14 inches of blown-in cellulose at $0.60–$2.30/sq ft hits the same R-49 target. Match the material to the application — see our chart.

2. Skipping air sealing. We say this in every article because it's the most common and most costly mistake. Insulation slows conductive heat transfer. Air sealing stops convective heat loss through gaps and penetrations. Without sealing the attic floor penetrations, top plates, duct boots, and recessed lights before insulating, you lose 15–25% of potential savings.

3. Wrong material in wet locations. Fiberglass batts in crawl spaces and basements is a recipe for mold and failure. We've torn out tons of soggy, black fiberglass from below-grade applications. Use closed-cell spray foam, rigid foam, or — if you must use fibrous insulation — mineral wool with proper moisture management.

4. Compressing batts around obstructions. Stuffing a fiberglass batt behind a wire or pipe instead of splitting it and fitting around the obstruction creates a void. That void has an R-value of approximately R-1 (still air in a thin gap). If 10% of a wall has voids, the whole wall loses far more than 10% of performance because heat flows preferentially through the weakest point. See our guide on what is R-value for why installation quality matters more than label R-value.

5. Ignoring thermal bridging. Filling wall cavities with R-21 insulation and calling the wall "R-21" ignores the 23–25% of the wall that's wood framing at R-1.25/inch. The whole-wall R-value is closer to R-17 — you can verify this with ORNL's whole-wall R-value calculator. If you're in zone 5+ and code requires R-20+5ci, the "5ci" (continuous insulation) part is what breaks the thermal bridge. Don't skip it.

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Key Takeaways

• Fiberglass is the most widely used and cheapest insulation ($0.30–$1.50/sq ft), but it's highly sensitive to installation quality.
• Cellulose (loose-fill and dense-pack) offers the best value for attic floors and wall retrofits, with 80%+ recycled content.
• Mineral wool leads in fire resistance (2,150°F+) and sound control (NRC 1.00–1.05) at a 40–70% cost premium over fiberglass.
• Closed-cell spray foam delivers the highest R-per-inch (R-6.0–R-7.0) plus air sealing plus moisture control, but at 3–5× the cost of basic materials.
• Rigid foam boards (EPS, XPS, polyiso) are essential for continuous exterior insulation and below-grade applications.
• Radiant barriers are effective supplements in hot climates (zones 1–3) only — they're not substitutes for conventional insulation.
• Always pair insulation with air sealing — the DOE estimates proper insulation + sealing reduces heating/cooling by 15–25%.
• Use our R-value chart to find the right R-value target, then pick the material that meets it for your application and budget.

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FAQ

What's the best type of insulation overall?

There's no single "best" — it depends entirely on the application. For open attics, blown-in cellulose or fiberglass offers the best value. For walls in new construction, fiberglass batts or mineral wool are standard. For basements and crawl spaces, closed-cell spray foam or rigid foam board. For soundproofing, mineral wool. For fire-rated assemblies, mineral wool. See the decision table above for application-specific recommendations.

What's the most cost-effective insulation?

Fiberglass batts at $0.30–$1.50/sq ft installed offer the lowest upfront cost. For attic floors, blown-in cellulose at $0.60–$2.30/sq ft provides the best balance of cost and performance. When you factor in air sealing benefits, open-cell spray foam can sometimes match cellulose on total value despite higher upfront cost — the combined insulation + air sealing in one step can save on labor. Use our insulation cost calculator for a head-to-head comparison.

Which insulation is best for soundproofing?

Mineral wool at NRC 1.00–1.05 provides the best sound absorption of any standard insulation material. It's the default choice for sound-rated wall assemblies (STC partitions), home theaters, and shared-wall applications. Cellulose (NRC 0.80–0.90) is a solid second choice. Closed-cell spray foam (NRC 0.50–0.70) is actually one of the worst for soundproofing because its rigid structure transmits sound rather than absorbing it. Full details in our soundproofing guide.

Can I mix different types of insulation?

Yes — and in many cases, you should. Common hybrid approaches include closed-cell spray foam on the sheathing side of a wall cavity topped with fiberglass batts (flash-and-batt), rigid foam over exterior sheathing with batt insulation in the cavity, and blown-in insulation on top of existing fiberglass batts in the attic. The key rule: don't trap a vapor retarder in the middle of the assembly. If you're adding insulation on top of faced batts, remove or slash the existing facing.

What's the best insulation for DIY installation?

Fiberglass batts and mineral wool batts are the most DIY-friendly — they require only a utility knife, straight edge, and safety gear (mask, gloves, long sleeves). Rigid foam boards are also DIY-installable with a score-and-snap technique. Loose-fill cellulose in an open attic is manageable with a rental blowing machine from a home center (some retailers provide the machine free with minimum material purchase). Dense-pack cellulose and all spray foam applications should be left to professionals — the equipment requirements, safety concerns, and quality-control demands exceed typical DIY capability.