Best Home Insulation Types Compared for 2026

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Choosing the right insulation is one of the smartest home improvement decisions you can make. Good insulation keeps your home comfortable year-round, cuts heating and cooling costs by 15 to 40 percent, and pays for itself within a few years. It is also the foundation of any effective home energy audit — checking your insulation levels is one of the first things to assess. But with five major insulation types on the market, picking the right one for your project can feel overwhelming.

This guide compares the most common home insulation materials — fiberglass batts, blown-in cellulose, open-cell spray foam, closed-cell spray foam, and mineral wool — by the factors that actually matter: R-value, cost, ease of installation, and where each one works best.

Quick Comparison: Home Insulation Types at a Glance

Before we dig into the details, here is a side-by-side snapshot of all five insulation types.

| Type | R-Value per Inch | Cost per Sq Ft | DIY-Friendly? | Air Seals? | Moisture Resistant? | |---|---|---|---|---|---| | Fiberglass batts | R-3.2 | $0.30–$1.50 | Yes | No | No | | Cellulose (blown-in) | R-3.5 | $0.60–$2.30 | Moderate | Partial | Partial | | Open-cell spray foam | R-3.7 | $1.00–$2.00 | No | Yes | No | | Closed-cell spray foam | R-6.5 | $1.50–$3.50 | No | Yes | Yes | | Mineral wool | R-4.3 | $1.40–$2.10 | Moderate | No | Yes |

R-value measures resistance to heat flow — the higher the number, the better the insulation performs per inch of thickness. Cost ranges reflect materials and typical installation for standard residential projects.

Fiberglass Batts: The Budget-Friendly Standard

Fiberglass batts are the pink or yellow rolls you see stacked at every hardware store. They have been the most popular residential insulation for decades, and for good reason — they are cheap, widely available, and straightforward to install yourself.

What You Get

Fiberglass batts deliver R-3.2 per inch at a cost of just $0.30 to $1.50 per square foot. Pre-cut batts are designed to fit standard 16-inch or 24-inch stud spacing, which makes wall cavity installation a manageable weekend project for most homeowners.

Where Fiberglass Falls Short

The biggest weakness of fiberglass is its sensitivity to installation quality. Gaps, compression, and voids around wires or pipes dramatically reduce performance. A batt that is even slightly compressed or that does not fill the cavity completely can lose 30 percent or more of its rated R-value. Fiberglass also does not air-seal, so you need separate caulking and weatherstripping to stop drafts.

Fiberglass absorbs moisture and loses R-value when wet, so it is not a great choice for damp basements or crawlspaces. You will also want to wear gloves, long sleeves, and an N95 mask during installation — the tiny glass fibers irritate skin and lungs.

Best For

Standard wall cavities, attic floors between joists, and any project where budget is the top priority and you are willing to do the work carefully.

Cellulose (Blown-In): Best for Attics and Retrofits

Cellulose insulation is made from roughly 85 percent recycled newspaper, treated with borate for fire and pest resistance. It is blown into place with a machine, which lets it fill irregular cavities and flow around obstacles that batts cannot handle.

What You Get

At R-3.5 per inch and $0.60 to $2.30 per square foot, cellulose offers a meaningful performance upgrade over fiberglass at a moderate price increase. Most big-box home improvement stores will loan you a blowing machine for free when you buy a certain number of bags, making attic insulation a realistic DIY project.

What to Watch For

Cellulose settles 10 to 20 percent over time, so professionals recommend blowing in 10 to 20 percent extra to compensate. It can absorb moisture in very humid environments, although the borate treatment provides good mold resistance. Cellulose also provides partial air-sealing — it reduces air movement better than batts but does not fully seal like spray foam.

Best For

Attic floors where you are blowing over existing insulation, retrofit wall cavities through small access holes (dense-pack cellulose), and irregularly shaped spaces where batts would leave gaps.

Open-Cell Spray Foam: Insulation Plus Air Sealing

Open-cell spray foam is a two-part chemical mixture that expands on contact to fill cavities and seal air leaks simultaneously. This two-in-one capability is its main advantage — you get insulation and air sealing in a single step.

What You Get

Open-cell spray foam delivers R-3.7 per inch at $1.00 to $2.00 per square foot. It expands to roughly 100 times its original volume, filling every crack and gap in the cavity. After curing, it remains soft and flexible, which is useful in structures that shift seasonally.

The Downsides

Professional installation is strongly recommended. While small DIY kits exist for spot sealing, filling an entire wall cavity or attic with consistent thickness and coverage requires the right equipment and experience. Open-cell foam is also vapor-permeable, meaning moisture can pass through it. In humid climates or below-grade applications, this can be a problem.

Best For

Wall cavities and attic rooflines where you want insulation and air sealing in one step. Open-cell foam is popular for cathedral ceilings and bonus rooms over garages where space is tight but you do not need the vapor barrier properties of closed-cell.

Closed-Cell Spray Foam: Maximum Performance

Closed-cell spray foam is the premium option. It has the highest R-value per inch of any common insulation material and doubles as both an air barrier and a vapor barrier.

What You Get

At R-6.5 per inch, closed-cell foam packs nearly twice the insulating power of fiberglass into the same space. It costs $1.50 to $3.50 per square foot and requires professional installation, but it delivers performance that no other single material can match. At two inches or more, it acts as a full vapor barrier, and it even adds structural rigidity to walls.

The Trade-Offs

Closed-cell foam is the most expensive insulation option, and the rigid finished product can crack if the building shifts significantly. It is also the most difficult to remove or modify later, so plan carefully before committing. The blowing agents used in some closed-cell foams have a higher global warming potential than other insulation types, although newer formulations are improving on this front.

Best For

Basement and crawlspace walls, rim joists, areas with extreme space limitations where you need maximum R-value in minimal thickness, and flood-prone areas where moisture resistance is critical.

Mineral Wool: The Fire-Resistant Performer

Mineral wool (sold under brand names like Rockwool) is made from volcanic rock or industrial slag spun into fibers. It has been gaining popularity among homeowners and builders who want better performance than fiberglass without the complexity of spray foam.

What You Get

Mineral wool delivers R-4.3 per inch at $1.40 to $2.10 per square foot. Its standout feature is fire resistance — it is rated to withstand temperatures up to 2,150 degrees Fahrenheit, making it the best choice for fire-rated wall assemblies. It is also naturally hydrophobic, meaning it repels water rather than absorbing it, so it retains its R-value even in damp conditions.

Installation Notes

Mineral wool batts are denser and heavier than fiberglass, which makes them slightly harder to cut and handle. You will need a serrated knife or bread knife rather than a utility knife. On the plus side, the extra density means the batts hold their shape well, stay in place without fasteners in friction-fit applications, and provide excellent soundproofing.

Best For

Exterior walls where moisture resistance matters, fire-rated assemblies, basement walls, soundproofing between rooms, and any situation where you want better-than-fiberglass performance without hiring a spray foam contractor.

How to Choose the Right Insulation for Your Project

The best insulation depends on where you are installing it, your budget, and whether you plan to do the work yourself.

Choose Fiberglass Batts If

You are on a tight budget, your wall cavities are standard dimensions with few obstructions, and you are comfortable with careful DIY installation.

Choose Blown-In Cellulose If

You are insulating an attic floor, adding insulation over existing material, or retrofitting walls without removing drywall.

Choose Open-Cell Spray Foam If

You need air sealing and insulation in one step, you are working with a professional installer, and you are insulating walls or rooflines.

Choose Closed-Cell Spray Foam If

You need maximum R-value in limited space, moisture resistance is critical (basements, crawlspaces, rim joists), or you are in a flood-prone area.

Choose Mineral Wool If

Fire resistance is important, you want moisture-resistant batts for exterior walls or basements, or soundproofing is a priority.

Do Not Forget Air Sealing

No matter which insulation you choose, air sealing should come first. Insulation slows heat transfer through materials, but air leaks bypass insulation entirely. Sealing gaps around plumbing penetrations, electrical boxes, attic hatches, and rim joists before insulating can improve your results by 15 to 25 percent. Check out our DIY air sealing guide for a step-by-step walkthrough.

Take Advantage of Tax Credits and Rebates

Federal and state programs can help offset the cost of insulation upgrades. Check our guide on how to stack energy rebates to maximize your savings. Many utilities also offer rebates of $200 to $800 for insulation upgrades. A professional energy audit ($200 to $400) can identify your biggest opportunities and often qualifies you for additional rebate programs.

Upgrading your home's insulation is one of the few improvements that pays you back every single month through lower energy bills. Start with the area that will give you the biggest return — for most homes, that is the attic. Pick the material that fits your budget and skill level, seal the air leaks first, and enjoy a more comfortable home with lower bills for decades to come.