Choosing insulation for your home usually comes down to two options, spray foam or batt. Both keep your home warmer in winter and cooler in summer, but they work in different ways and come at different price points. This guide breaks down the real differences in plain language, so you can pick what actually fits your project.
Key Takeaways
• Spray foam has a higher R value per inch and seals air leaks as it expands, while batt insulation is more budget friendly for open, regular shaped spaces.
• Closed cell spray foam typically reaches R-6 to R-6.5 per inch, versus R-3 to R-4 per inch for fiberglass batts.
• Batt insulation alone does not stop air leaks, since air can still move through gaps left around the material.
• Spray foam costs more upfront but often pays back through lower energy bills over time.
• Many homes use both, batts in open walls and attics, spray foam in tricky spots like rim joists and basements.
What Is Spray Foam Insulation?
Spray foam insulation is a liquid that expands into a solid foam once sprayed onto a surface. It fills gaps and odd shaped spaces that other insulation types often miss, which makes it strong for air sealing and thermal insulation at the same time.
Open Cell vs Closed Cell Spray Foam
• Open cell spray foam is softer, lighter, and allows some vapour to pass through, which makes it useful in areas where a vapour barrier is not wanted.
• Closed cell spray foam is denser, offers a higher R value per inch, and works as its own moisture barrier, which is why it is often used in basements and rim joists.
How Spray Foam Application Works
A trained crew mixes two chemical components on site, then sprays the mixture directly onto the wall, attic floor, or rim joist. It expands within seconds and hardens into place. Spray foam installation should always be done by a certified applicator, since proper ventilation and protective equipment are required.
What Is Batt Insulation?
Batt insulation comes in pre cut panels or rolls, usually fiberglass or mineral wool, sized to fit standard wall cavities and attic joist spacing. It is one of the most common home insulation types because it is affordable and straightforward to install in open areas.
Fiberglass Batts vs Mineral Wool Batts
• Fiberglass batt insulation is the most widely used option, made from fine glass fibers, and is generally the cheaper of the two materials.
• Mineral wool batts cost a bit more but offer better fire resistance and slightly better soundproofing, which some homeowners value in shared walls.
How Batt Insulation Installation Works
Batts are cut to size and pressed into place between wall studs, floor joists, or attic rafters. Correct installation matters here, gaps, compression, or loose fitting batts all reduce performance significantly, even if the material itself is rated well.
Spray Foam vs Batt Insulation R Value, Which Insulates Better?
R value measures how well a material resists heat flow. The higher the number per inch, the better it insulates.
• Closed cell spray foam typically rates R-6 to R-6.5 per inch.
• Open cell spray foam typically rates R-3.5 to R-3.6 per inch.
• Fiberglass batt insulation typically rates R-3 to R-4 per inch.
• Mineral wool batts typically rate R-3.7 to R-4.2 per inch.
So when comparing spray foam vs fiberglass R value directly, closed cell spray foam wins per inch. That said, batt insulation can still reach a similar total R value if installed at a greater depth, which is common in attic applications.
Does Batt Insulation Stop Air Leaks As Well As Spray Foam?
No, not on its own. This is one of the biggest differences between the two materials.
• Spray foam expands into every gap and crack, creating a continuous air seal as it cures, which stops drafts and air leakage at the same time it insulates.
• Batt insulation slows heat transfer through the material itself, but it does not seal air movement around it. Gaps at the edges, behind electrical boxes, or where batts are cut poorly still allow air to pass through.
This is why many contractors pair batt insulation with separate air sealing steps, caulking or spray foam at penetrations, to get closer to the air sealing performance spray foam offers on its own.
Spray Foam vs Batt Insulation Cost, Which Is Cheaper?
Batt insulation is cheaper upfront, both in material and installation cost. Here is a general breakdown for cost per square foot.
Average Spray Foam Insulation Cost
• Open cell spray foam typically runs from about 1.00 to 1.75 dollars per square foot installed.
• Closed cell spray foam typically runs from about 1.50 to 3.00 dollars per square foot installed, sometimes higher depending on access and project size.
Average Batt Insulation Cost
• Fiberglass batt insulation typically runs from about 0.50 to 1.50 dollars per square foot installed.
• Mineral wool batts run slightly higher, usually around 1.00 to 2.00 dollars per square foot installed.
Fiberglass Insulation vs Spray Foam Cost Over Time
While fiberglass insulation vs spray foam cost clearly favours batts upfront, spray foam’s air sealing often reduces energy bills more over time, which changes the long term value picture. The right choice depends on your budget today versus what you want to save later.
Is Spray Foam Worth The Extra Cost?
For many homeowners, yes, especially in specific areas of the home.
• In basements, rim joists, and crawl spaces, spray foam’s moisture resistance and air sealing ability often justify the higher price, since these areas are prone to leaks and drafts that batts cannot fully address.
• In simple, open wall cavities with no odd angles or penetrations, batt insulation often performs nearly as well for a fraction of the cost, making spray foam a less necessary upgrade there.
Is spray foam better than batt insulation really comes down to where it is being used, not which product is universally superior. Matching material to application matters more than picking one type for the whole house.
Can You Use Spray Foam And Batt Insulation Together?
Yes, and it is actually a common approach. Many homes combine spray foam or fiberglass insulation strategically rather than choosing only one type for the entire building.
• Spray foam gets used at rim joists, around plumbing and electrical penetrations, and in basement walls where air sealing and moisture control matter most.
• Batt insulation gets used in open attic floors and standard wall cavities, where cost effective coverage over a large area is the priority.
This hybrid approach often delivers the best balance of performance and cost, giving you targeted air sealing where it matters most without paying spray foam prices across the whole home.
Which Insulation Is Better For Your Home?
When To Choose Spray Foam
• Basements, crawl spaces, and rim joists where moisture control matters
• Attics or walls with irregular framing, pipes, or wiring that batts cannot fit around cleanly
• Homes with a history of drafts, ice damming, or high energy bills tied to air leakage
When To Choose Batt Insulation
• Open, standard sized wall cavities with no obstructions
• Projects with a tighter budget where upfront cost matters most
• Large attic floors where depth can be added easily to reach target R values
Conclusion
There is no single winner in the spray foam vs batt insulation debate, it depends on the space, the budget, and the problem you are trying to solve. Spray foam offers a higher R value per inch and built in air sealing, while batt insulation remains more affordable for open areas. Many Ottawa area homes end up using a mix of both.
If you are not sure which option fits your home, our team can walk you through it. Learn more about our spray foam insulation services or our batt insulation services, or visit jarrahcs.com for a free, no pressure quote.
Frequently Asked Questions
Which is cheaper, spray foam or batt insulation?
Batt insulation is cheaper upfront. Fiberglass batts typically cost 0.50 to 1.50 dollars per square foot installed, while spray foam runs 1.00 to 3.00 dollars per square foot depending on type.
Does spray foam have a higher R value than fiberglass batts?
Yes. Closed cell spray foam rates around R-6 to R-6.5 per inch, compared to R-3 to R-4 per inch for fiberglass batts.
Does batt insulation stop air leaks?
Not on its own. Batt insulation slows heat transfer but does not seal air movement the way spray foam does. It usually needs separate air sealing for best results.
Is spray foam worth the extra cost?
Often, yes, in basements, rim joists, and areas with irregular framing where moisture control and air sealing matter most. In simple open cavities, batts can be more cost effective.
Can you use spray foam and batt insulation together?
Yes, this is common practice. Spray foam handles tricky spots like rim joists and penetrations, while batt insulation covers larger, open areas at lower cost.