When it comes to home insulation, choosing the right material significantly impacts energy efficiency, air sealing, and moisture resistance. Closed-cell spray foam insulation and traditional batt insulation—including fiberglass and rock wool batt insulation—are two of the most popular options, each offering unique advantages.
While spray foam insulation provides a high R-value, superior air sealing, and long-term durability, batt insulation remains a cost-effective and DIY-friendly alternative. But which one is the best choice for your home?
In this guide, we’ll break down the key differences, pros and cons, cost factors, and best use cases to help you make an informed decision. Whether you're insulating an attic, crawl space, or garage, this comparison will ensure you choose the right solution for maximum efficiency and long-term savings.
What Is Closed-Cell Spray Foam Insulation?
Spray foam insulation is a modern insulation solution that creates an airtight barrier when applied. The closed-cell variety contains tiny cells filled with gas that are pressed together, creating a dense, rigid foam structure. When applied, insulation foam expands and hardens, filling every crack and crevice in the project area. Modern DIY kits make this professional-grade solution accessible to experienced home improvers. When properly installed using a spray foam insulation kit, it provides exceptional insulation and moisture resistance.
What Is Batt Insulation?
Batt insulation represents the traditional approach to home insulation, coming in pre-cut panels that fit between wall studs, joists, and beams. Fiberglass batt insulation and rock wool are the two primary types of insulation batt, each offering unique advantages for different applications.
What Are the Types of Batt Insulation?
By Material:
Fiberglass batt insulation consists of fine glass fibers and remains the most common choice for residential applications. Rockwool insulation batts, made from mineral wool, offer an alternative with enhanced fire resistance properties.
By Facing Options:
Batts insulation comes in two facing variations: faced and unfaced. Faced batt insulation includes a vapor barrier for moisture control, while unfaced batt insulation provides flexibility for layering and interior applications where moisture resistance isn't critical.
How Do Closed-Cell Spray Foam and Batt Insulation Compare?
Understanding the key differences between these insulation types helps make an informed decision for your project.
- Closed-cell spray foam: Highest R-value, air-sealing, and moisture resistance
- Fiberglass batt insulation: Budget-friendly, easy installation, lower R-value
- Rock wool batt insulation: Higher fire resistance and better durability than fiberglass
The following table provides a detailed side-by-side comparison of these insulation types, highlighting their strengths and limitations:
| Feature | Closed-Cell Spray Foam | Fiberglass Batt | Rock Wool Batt |
|---|---|---|---|
| R-Value (Thermal Efficiency) | Higher (5.6-8.0 per inch) | Lower (2.9-3.8 per inch) | Moderate (3.0-4.2 per inch) |
| Air Sealing | Excellent (creates airtight barrier) | Poor (requires additional sealing) | Good (but requires additional sealing) |
| Moisture Resistance | Offers superior water resistance (acts as a vapor barrier) | Depends on Facing | Water-resistant |
| Soundproofing | Good | Fair | Excellent |
| Durability | Does not sag | May sag | More durable than fiberglass |
| Lifespan | 50+ years | 15-20 years | 20-30 years |
| Fire Resistance | Fire-resistant (depends on product) | Non-combustible but melts at high temps | High fire resistance |
| Installation | Spray-applied, professional & DIY options | DIY-friendly, roll or cut-to-fit | DIY-friendly, denser but manageable |
| Cost | High ($0.75-$4.50 per sq ft) | Lower ($0.30-$1.80 per sq ft) | Moderate ($1.40-$3.80 per sq ft) |
Cost information is according to SPRAYMAN, HomeAdvisor, and other industry sources. Cost ranges depend on factors such as R Value, brand, or installation option (PRO/DIY).
Benefits and Drawbacks
When choosing between closed-cell spray foam and batt insulation, it’s essential to weigh their advantages and disadvantages based on your specific project needs.
The following table highlights each insulation type's key pros and cons, helping you decide which option best suits your home, budget, and energy efficiency goals.
| Insulation Type | Pros | Cons |
| Closed-Cell Spray Foam | - Superior insulation performance - Excellent air & moisture barrier - Adds structural strength - Long lifespan |
- Higher initial cost - Requires precise application |
| Batt Insulation | - Most affordable insulation option - Easy to install |
- Lower R-value - Can settle over time - Requires separate vapor barrier - Less effective in extreme temperatures - Less effective air sealing |
When Should You Use Closed-Cell Spray Foam vs Batt Insulation?
Choose closed-cell foam insulation for:
- High-moisture environments and humid climates
- Areas requiring maximum air sealing
- Spaces where high R-value per inch is crucial
- Challenging areas like crawl spaces
- Regions with extreme temperature variations
- Projects where long-term energy efficiency is a priority
Consider batt insulation when:
- Working with a limited budget
- Retrofitting existing walls
- Simple installation between standard-sized framing
In summary, closed-cell spray foam is the ideal choice if you're looking for maximum energy efficiency and moisture resistance. However, if budget is your primary concern, batt insulation offers a cost-effective alternative.
FAQs
How Much Does Spray Foam Insulation Cost?
On average, DIY spray foam insulation kits cost between $0.75 and $2.00 per square foot, while professional installation ranges from $1.00 to $4.50 per square foot. Read our in-depth guide on spray foam insulation costs.
What Is an R-Value of Insulation?
R-value measures thermal resistance—the higher the value, the better the insulation performance. Learn why R-value is crucial for insulation efficiency in our guide.
Is Spray Foam Insulation Better Than Fiberglass Insulation?
Yes, but the best choice depends on your needs. Spray foam insulation offers superior air sealing and a higher R-value per inch, while fiberglass batt insulation remains the more budget-friendly option.
Can You Install Spray Foam Insulation Yourself?
Yes, spray foam insulation kits make DIY installation easier, but success depends on careful preparation and proper safety precautions. If you're new to spray foam, consider starting with a small project before tackling larger areas.
Which Insulation Is Best for Crawl Spaces?
Closed-cell spray foam insulation is the best choice for crawl spaces. Its superior moisture resistance and air-sealing properties make it ideal for damp environments where fiberglass batt insulation may absorb moisture and lose effectiveness.
Spray Foam vs Fiberglass Insulation: What's Best for Insulating a Garage?
Closed-cell spray foam is the best insulation option for garages, offering superior energy efficiency, air sealing, and durability compared to fiberglass batt insulation.
How Does Open-Cell Compare to Closed-Cell Spray Foam?
Open-cell spray foam is lighter and more affordable than closed-cell but has a lower R-value and less moisture resistance. Closed-cell remains the preferred choice for exterior walls and areas requiring waterproofing insulation. Explore our full comparison of open-cell vs. closed-cell spray foam insulation.
Can Spray Foam and Batt Insulation Be Used Together?
Combining expandable foam for air sealing with traditional batt insulation can create an effective hybrid system, especially in retrofit projects. For example, applying expanding foam spray around outlets and gaps before installing batt insulation in wall cavities.
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