When it comes to insulating your home, two of the most popular options are spray foam insulation and fiberglass batt insulation. Both have their advantages and disadvantages when it comes to factors like insulation performance, cost, and ease of installation. Many homeowners wonder which option is more cost effective in the long run.
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What is spray foam insulation?
Spray foam insulation is a two-part liquid insulation material that is sprayed onto surfaces and expands to fill cracks and voids. The two liquid components (isocyanate and resin) are kept separate until they are pumped through a spray gun where they combine and expand on contact.
The foam quickly expands 30-60 times its original size to fill the space completely. This helps stop air leaks and insulates more thoroughly than other materials. Once cured, the rigid foam adheres tightly to the underlying surface.
Spray foam insulation is available in two types: open-cell and closed-cell. Open-cell spray foam is softer and allows vapor and moisture to pass through. Closed-cell foam is denser and provides a moisture barrier.
Advantages of Spray Foam Insulation
- Fills cracks and crevices thoroughly
- Blocks drafts and air leaks
- Adheres tightly to surfaces
- High insulation value (R-value of 6-8 per inch)
- Adds structural stability
- Moisture resistant options available
What are fiberglass batts?
Fiberglass batt insulation consists of thin, fluffy mats made from spun glass fibers. The batts are available in various widths suited for spacing between wall studs or attic joists.
Fiberglass offers good insulation performance at a low cost. It is the most commonly used type of insulation in homes. The batts are easy to cut and install between framing members. However, fiberglass does not fill small gaps as thoroughly as foam.
Advantages of Fiberglass Batt Insulation
- Low cost
- Easy to install between studs and joists
- Readily available
- High insulation value (R-3.14 per inch)
- Won’t compress over time
Insulation Performance
When comparing the insulating performance of spray foam vs. fiberglass batts, spray foam comes out ahead.
The R-value provided by spray foam insulation ranges from R-3.6 to R-6.5 per inch depending on the type of foam. Fiberglass batts typically provide an R-value around R-3.2 per inch.
Since spray foam completely fills gaps and adheres tightly, it minimizes air leaks. Fiberglass batts often have small air gaps around the edges which can reduce the real-world insulation performance.
R-value per Inch
| Insulation Type | R-value per Inch |
|---|---|
| Open-Cell Spray Foam | R-3.6 to R-4.0 |
| Closed-Cell Spray Foam | R-6.0 to R-6.5 |
| Fiberglass Batt | R-3.2 |
So while a standard 6-inch fiberglass batt provides an R-value of around R-19, the same thickness of closed-cell spray foam would provide R-38 to R-39.
Installation Costs
One of the biggest differences between spray foam vs. fiberglass is the installation cost. Let’s break down the costs in more detail:
Spray Foam Installation Costs
– Equipment and labor: Since special equipment is required to spray foam correctly, most homeowners hire a professional insulation contractor. Expect to pay $1,200 to $1,800 per day in labor and equipment costs.
– Materials: The chemicals that make up the foam are expensive, running $0.80 to $1.50 per board foot installed. For a typical 2,000 sq.ft. home, material costs range from $1,600 to $3,000.
– Total installed cost: Combining labor, equipment, and materials, homeowners pay between $3 to $6 per square foot for professionally installed spray foam insulation.
Fiberglass Batt Installation Costs
– DIY labor: Installing fiberglass batts is a DIY-friendly project for many homeowners. If you handle the installation yourself, you avoid paying for expensive professional installation.
– Materials: Fiberglass batts cost approximately $0.25 to $0.35 per square foot for R-13 to R-15 batts. Higher density batts with R-21 rating cost $0.45 to $0.55 per square foot.
– Total installed cost: Factoring in just the material cost, fiberglass batt insulation averages between $0.25 and $0.55 per square foot when self-installed.
In summary, installed spray foam insulation costs 5 to 10 times more than fiberglass batts per square foot when professionally installed.
Coverage and Gaps
Since spray foam completely fills any cavity and seals cracks, you may use up to 20% less foam to insulate the same space compared to fiberglass. There is less chance for gaps that undermine the insulation performance.
Fiberglass batts often become compressed and leave small air gaps around framing where cold air can penetrate. Proper installation is critical to ensure insulation consistency and reduce gaps.
Moisture Considerations
Closed-cell spray foam provides a moisture and vapor barrier, an advantage in damp climates. Fiberglass alone does not stop moisture penetration. Often an additional vapor barrier must be installed to prevent condensation issues.
Spray polyurethane foam contains toxic chemicals and gases that can be released while spraying. Proper protective equipment is mandatory for anyone in the vicinity while spraying.
Longevity
Both spray foam and fiberglass batt insulation are long-lasting options. As long as they remain undamaged, they will insulate effectively for decades. Homeowners may forget about the insulation after installation.
If installed correctly in the first place, neither material decomposes or settles significantly over time. Spray foam adheres tightly while fiberglass batts are flexible.
Conclusion
There are good reasons why both spray foam and fiberglass batt insulation remain popular choices. Here are some key points to help determine which suits your home and budget:
– Spray foam has a superior insulation value (R-6 per inch) compared to fiberglass (R-3 per inch). It minimizes gaps, air leaks, and drafts more effectively.
– Fiberglass batt installation is a DIY-friendly project that costs 5-10 times less per square foot than professionally installed spray foam.
– Closed cell spray foam provides insulation, air sealing, and a vapor barrier in one step. Fiberglass may require an additional vapor barrier.
– Spray foam insulation covers hard-to-reach areas easily. Fiberglass batts are better suited for straightforward cavities between studs and joists.
– Both insulation types are long-lasting if installed properly. Performance won’t degrade significantly over decades.
For maximum energy efficiency, spray foam is the best overall choice if the added cost fits into your budget. If looking for an affordable option, fiberglass batt installation is a cost-effective DIY project. Carefully compare the pros, cons, and costs of spray foam vs fiberglass insulation before deciding on the right type for your home.