Spray Foam Insulation vs Fiberglass Batt Insulation: Which Is Right for Your Home?
High energy bills and uncomfortable rooms are common problems for homeowners. The right insulation can fix these issues by keeping your home warm in winter and cool in summer. This guide compares spray foam insulation vs fiberglass so you can choose with confidence. You will see how spray foam insulation improves air sealing and R-value, and how fiberglass batt insulation delivers a low-cost, DIY-friendly option. We will review performance, cost, and installation for each material.
Understanding the Two Insulation Types
Before comparing, it is important to know the basics of each material. Both provide insulation, but they work in very different ways.
What Is Spray Foam Insulation?
Spray foam insulation is a liquid insulation that expands into a solid foam after it is sprayed. It fills every crack and gap, creating a complete air seal. This seal stops air leaks, which are a major source of energy loss. Closed-cell spray foam also acts as a moisture barrier, protecting your home from water damage and mold. This type is known for high performance and durability.
What is Batt Insulation?
Fiberglass batt insulation consists of pre-cut panels made from fine glass fibers. It is one of the most common types of home insulation. Installers place the batts between wall studs, ceiling joists, and floor joists. For effective results, fiberglass often needs a separate air barrier and vapor retarder to control air leakage and moisture.
Spray Foam Insulation vs. Fiberglass: A Detailed Breakdown
The choice between spray foam vs batt insulation depends on key factors. The sections and tables below compare them on R-value, air and moisture control, cost, installation, and durability.
Thermal Performance (R-Value)
R-value measures how well an insulation material resists heat flow. A higher R-value means better insulating power. The high spray foam R-value provides more insulation in less space. The table below compares the R-value per inch and air sealing for spray foam insulation and fiberglass batt insulation.
|
Feature |
Spray Foam Insulation |
Fiberglass Batt Insulation |
|
R-value per inch |
5.6 to 8.0 (closed-cell type) |
2.9 to 3.8 |
|
Air Sealing |
Excellent (creates an airtight seal) |
Poor (requires a separate air barrier) |
Air and Moisture Control
Controlling air and moisture is critical for energy efficiency and structural health. Spray foam offers an all-in-one solution. The table below shows how each insulation handles vapor barriers, air leakage protection, and moisture resistance.
|
Attribute |
Spray Foam Insulation |
Fiberglass Batt Insulation |
|
Vapor Barrier |
Built-in (closed-cell type) |
Requires facing or a separate film |
|
Air Leakage Protection |
Complete |
Weak without extra sealing |
|
Moisture Resistance |
High |
Low (can hold moisture) |
Cost Analysis: Investment vs. Long-Term Value
Cost is a major factor for any home project. Fiberglass is cheaper upfront, but spray foam can provide greater energy savings over time. The table below lists installed cost per square foot and the expected long-term value for each option.
|
Type |
Total Installed Cost per Sq Ft |
Long-Term Value |
|
Spray Foam Insulation |
$0.75 – $4.50 |
High (due to energy savings) |
|
Fiberglass Batt Insulation |
$0.30 – $1.80 |
Moderate |
Installation: DIY vs. Professional
Installation complexity affects both the cost and time of a project. Fiberglass is much simpler for DIY installations. The table below outlines the installation method and DIY suitability for both materials.
|
Insulation Type |
Installation Method |
DIY Suitability |
|
Spray Foam |
Applied with a spray gun, requires PPE |
Moderate (DIY kits exist but need care) |
|
Fiberglass Batt |
Pre-cut batts fit between studs |
High (common for DIY projects) |
Lifespan and Durability
Insulation is a long-term investment. Spray foam lasts significantly longer because it does not settle or degrade from moisture. The table below summarizes expected lifespan and compression risk for each insulation type.
|
Feature |
Spray Foam Insulation |
Fiberglass Batt Insulation |
|
Expected Lifespan |
50+ years |
15–20 years |
|
Compression Risk |
None |
Moderate (can settle over time) |
When Should You Choose Each Insulation Type?
Use this guide to make the best choice for your specific needs.
Choose spray foam insulation if:
- You want the highest possible energy efficiency and lower utility bills.
- You need to seal irregular or hard-to-reach spaces like attics, rim joists, or crawlspaces.
- Moisture control is important, such as in basements.
- You want a durable, long-term solution that will not need replacement.
Choose fiberglass batt insulation if:
- You have a limited budget for your project.
- You are insulating standard framed walls, floors, or ceilings.
- You plan to install the insulation yourself.
- The project is a simple retrofit in an existing space.
Conclusion
Your choice between spray foam insulation vs fiberglass depends on your budget, project goals, and performance needs. Fiberglass offers a low-cost, easy-to-install solution for standard applications. Spray foam provides superior performance, durability, and energy savings for homeowners seeking a long-term investment.
Ready to improve your home's energy efficiency? Explore our spray foam insulation kits today to start saving.
Frequently Asked Questions
Is spray foam insulation better than fiberglass?
Spray foam is generally better. It creates a superior air seal, has a higher R-value, and resists moisture more effectively than fiberglass. However, fiberglass is less expensive and easier for DIY installation.
What is the updated spray foam R value?
Closed-cell spray foam has an R-value of 5.6 to 8.0 per inch. Open-cell foam has a lower R-value, typically around 3.5 per inch.
For more information you can read our article titled “What Is the R-Value of Spray Foam Insulation and Why Does It Matter?”.
What is batt insulation used for?
It is used to insulate spaces with standard framing, such as walls, ceilings, and floors. It is a cost-effective choice for many new construction and retrofit projects.
Can I install spray foam myself?
Yes, you can use DIY spray foam kits. However, the process requires proper preparation, safety gear, and good ventilation. For large jobs, professional installation is recommended. Spray foam insulation application is easy to use for small projects.
Why does fiberglass batt insulation have a shorter lifespan?
Fiberglass can settle over time, creating gaps that reduce its effectiveness. It can also absorb moisture if not protected by a vapor barrier, which leads to mold and degradation.
What is the difference between open-cell and closed-cell spray foam?
Open-cell: ~R-3.5/in, vapor-permeable; best for interior walls/ceilings and sound control. Closed-cell: ~R-5.6–8.0/in, vapor barrier; best for basements, crawl spaces, rim joists, thin cavities, and extreme climates.
For details, see “How Do Open-Cell and Closed-Cell Spray Foam Differ?”.