Spray Foam vs Batt Insulation for Steel Buildings

When insulating a steel building in Canada, spray foam insulation and batt insulation are the two main contenders. Here’s what you need to know:

Spray Foam Insulation: Best for energy efficiency, moisture control, and long-term durability. Closed-cell spray foam seals gaps, prevents condensation, and eliminates thermal bridging, making it ideal for heated spaces and harsh Canadian climates. However, it’s more expensive upfront at CA$1.50–$3.50 per square foot.
Batt Insulation: A budget-friendly option for unconditioned spaces like garages or barns. Fibreglass batts cost CA$0.30–$0.80 per square foot but struggle with thermal bridging and moisture issues, reducing their effectiveness over time.

Quick Comparison

Feature	Spray Foam (Closed-Cell)	Batt Insulation (Fibreglass)
R-Value per Inch	R-6.0 to R-6.5	R-2.9 to R-3.8
Thermal Bridging	Eliminates heat pathways	Steel remains exposed
Moisture Resistance	Excellent	Poor without vapour barrier
Cost (30×50 ft)	CA$3,150–$7,350	CA$600–$1,700
Durability	Lifetime performance	Degrades after 10–15 years
Best Use	Heated spaces, harsh climates	Storage, barns, low budgets

Bottom Line: Choose spray foam for conditioned spaces and long-term savings. Opt for batts if cost is the priority and temperature control isn’t critical.

Spray Foam vs Batt Insulation for Steel Buildings in Canada

Spray Foam and Batt Insulation: An Overview

Spray Foam Insulation

Spray foam insulation is a two-part mixture that expands into a solid layer, adhering directly to surfaces. It comes in two varieties: open-cell and closed-cell.

Closed-cell spray foam (CCSF) is particularly well-suited for steel buildings. It’s dense, resists water, and provides an excellent R-value of 6.0 to 6.5 per inch. When applied at a thickness of 5 cm (2 inches) or more, it serves as both a complete air barrier and a Class II vapour retarder, eliminating the need for a separate vapour barrier. One of its standout features is its ability to coat the steel frame itself, which is key to addressing thermal bridging.

"Closed-cell spray foam is the preferred choice for metal buildings. It prevents condensation on steel framing, acts as a vapor barrier, eliminates thermal bridging through the frame, and delivers R-6.5/inch." – Kraken Bond Team

Open-cell foam, on the other hand, has a lower R-value of 3.5 to 3.7 per inch and doesn’t include a vapour barrier. This makes it better suited for indoor applications or soundproofing, but it’s not ideal for the cold conditions often found in Canadian winters.

When applying spray foam, the steel surface should be between 10°C and 32°C (50°F–90°F). If the steel drops below 4°C (40°F), adhesion issues can arise. Additionally, to meet building codes, a thermal barrier like 12 mm gypsum board or an intumescent coating must be applied.

While spray foam offers impressive performance, batt insulation follows a different approach with its own set of pros and cons.

Batt Insulation

Batt insulation, typically made of fibreglass, is sold in panels or rolls and installed between framing members like purlins and girts. It’s straightforward to install and is priced between $0.30 and $0.80 per square foot.

Fibreglass batt insulation has an R-value range of 2.9 to 3.8 per inch. However, in steel buildings, this number can be misleading. Since batts are placed between the framing, the steel remains exposed. Steel conducts heat about 400 times more efficiently than mineral wool insulation, which leads to thermal bridging. This can reduce the insulation assembly’s effective R-value by 30% to 50%.

Batt insulation is also air-permeable, so a separate vapour retarder – such as kraft-faced batts or a polyethylene membrane – is necessary to prevent moisture from reaching the steel. Without this barrier, condensation can form on the cold metal, leading to "morning drip" and potentially causing corrosion.

How Spray Foam and Batt Insulation Compare for Canadian Steel Buildings

Thermal Performance and Energy Efficiency

One key difference between spray foam and batt insulation lies in how they handle thermal bridging. Batt insulation leaves steel elements exposed, allowing heat to escape through these pathways. On the other hand, closed-cell spray foam adheres directly to the steel frame, effectively breaking those heat pathways.

"Without thermal breaks, steel purlins and girts act as thermal bridges that can reduce an assembly’s effective R-value by 30 to 50 percent compared to the nominal rated R-value of the insulation alone." – National Insulation Authority

Air leakage is another major source of energy loss in metal buildings, accounting for 25% to 40% of total energy loss. Fibreglass batts, being air-permeable, don’t stop drafts, while spray foam seals every gap and seam, creating a complete air barrier. In Canada’s colder climate zones, such as zones 7 and 8 (covering northern Ontario, the Prairies, and much of the territories), building codes often require roof assemblies to achieve R-38 or higher. Batt insulation struggles to meet these standards reliably, especially when factoring in thermal bridging losses.

But energy efficiency isn’t the only factor to consider – moisture management is equally important for steel buildings in Canada.

Condensation and Moisture Control

Steel cools rapidly, which can lead to condensation. For example, on a typical Canadian winter morning with exterior temperatures around −1°C and an interior temperature of 21°C at 50% relative humidity, steel panels and framing can drop below the dew point. This results in moisture forming on the metal, potentially leading to dripping, rust, and even structural corrosion over time.

Closed-cell spray foam provides a protective thermal buffer, preventing condensation from forming on steel surfaces. Fibreglass batts, however, don’t offer this benefit. Without a proper vapour retarder, moisture can pass through the batt material and condense on the cold steel behind it. Even with a vapour barrier, the steel framing remains vulnerable. In Canadian climate zones, vapour retarders are a mandatory requirement, and spray foam naturally meets this standard when applied at a thickness of 5 cm (2 inches) or more.

Cost and Return on Investment

The upfront cost of spray foam is significantly higher than batt insulation. Batt insulation typically costs CA$0.30–$0.80 per square foot, while closed-cell spray foam ranges from CA$1.50–$3.50 per square foot. Shaun Falls, Owner & Founder of Spray Foam Kings, estimates the installed cost of spray foam in Ontario to fall between:

"Between $4.00 and $8.00 per board foot installed."

For a 30 × 50 ft. (9 × 15 m) steel building with 195 m² (2,100 sq. ft.) of surface area, this cost difference is substantial. However, spray foam’s durability and performance make it a worthwhile investment, especially in Canada’s colder regions. Fibreglass blankets often lose their effective R-value within 10 to 15 years in metal buildings, while spray foam retains its installed R-value for the structure’s lifetime. Proper insulation can result in 25% to 50% energy savings compared to an uninsulated steel building, making spray foam a smart long-term choice for energy efficiency and moisture control.

When Spray Foam Is the Right Choice

High-Performance Applications

Spray foam insulation stands out as a practical solution for applications where thermal bridging and condensation are significant concerns. Steel buildings, known for their high thermal conductivity, benefit greatly from spray foam. It’s particularly effective in structures like heated barndominiums, workshops, and commercial offices, where maintaining consistent interior temperatures year-round is essential. Closed-cell spray foam directly coats the steel framing, breaking thermal bridges and ensuring steady indoor temperatures.

Moisture-heavy environments also make a strong case for spray foam. Facilities used for activities such as welding, woodworking, or housing livestock often generate substantial moisture. Spray foam’s built-in vapour barrier prevents condensation, a common issue in these settings.

Take the example of Brad and Shirley Houlden, who built a 22,200-square-foot hybrid steel facility in Cambridge, Nebraska, in November 2019. This area experiences extreme winter conditions similar to those in the Canadian Prairies. By applying Lapolla FOAM-LOK 2000 4G closed-cell spray foam (6.5 inches on the roof underside and 2 inches on the walls), they managed to keep their winter heating bills under $100 per month. In contrast, a nearby 8,000-square-foot shop insulated with fibreglass had monthly heating costs exceeding $250.

"Insulation performance is properly assessed by reviewing the combination of air movement, moisture control, health, safety, durability, comfort and energy efficiency with SPF scoring high marks in all categories when applied in metal buildings." – Rick Duncan, Ph.D., PE, Technical Director, Spray Polyurethane Foam Alliance

Spray foam doesn’t just tackle energy efficiency and moisture issues – it also brings additional physical benefits to the table.

Structural Benefits

Closed-cell spray foam does more than insulate – it strengthens steel structures. Once applied, it bonds seamlessly to steel panels, increasing racking resistance by 200–300% while sealing gaps that could allow air, insects, or rodents to enter. This added rigidity is especially valuable in regions prone to heavy snow and strong winds, such as Saskatchewan, Manitoba, and northern Ontario. By reinforcing walls and roofs, spray foam helps buildings withstand these harsh conditions.

"The rigid nature of closed-cell spray foam adds strength and rigidity to the walls and roof, making the building more resistant to wind and snow loads." – Shaun Falls, Owner & Founder, Spray Foam Kings

For steel buildings facing Canada’s challenging climate, spray foam provides a comprehensive solution, combining energy efficiency, moisture control, and structural durability in a single application.

Fake News Series | 1 | Comparing the R-Value of Batts to Spray Foam Insulation.

When Batt Insulation Is the Right Choice

While spray foam delivers high performance, batt insulation stands out as a budget-friendly and DIY-friendly option for the right applications.

Cost-Effective Uses

For many Canadian steel building owners, fibreglass batts are an affordable alternative – costing about 3 to 5 times less upfront than closed-cell spray foam. To put this into perspective, insulating a 30×50 ft building with batts might cost around CA$600–$1,700, whereas spray foam could run from CA$3,150–$7,350. This makes batts a sensible choice for buildings like vehicle storage garages, metal sheds, or agricultural pole barns where strict temperature regulation isn’t a priority.

If you’re on a tight budget, you can still improve energy efficiency by using spray foam cans (costing roughly CA$200–$500) to seal gaps and seams before installing batts. This small step can make a noticeable difference in performance without significantly increasing costs.

DIY and Accessibility Benefits

Fibreglass batts are a go-to for DIY enthusiasts because they’re easy to handle and install. They fit snugly between standard framing members and don’t require any special tools, saving you CA$0.30–$0.50 per square foot in labour costs compared to hiring a contractor. For larger areas, insulation rolls can be a better option, offering more seamless coverage and reducing the chances of gaps.

That said, fibreglass batts perform best in dry environments. Since they don’t naturally prevent condensation on exposed steel surfaces, it’s smart to use a kraft-faced product or add a polyethylene vapour barrier – especially crucial for DIY projects in Canada’s varied climates. Keep in mind that without proper upkeep, batts can sag and lose efficiency over a span of 10–15 years.

Choosing the right insulation ultimately comes down to your building’s purpose, local climate, and how much you’re willing to spend – topics that will be covered in the next section.

Choosing the Right Insulation for Your Steel Building in Canada

Climate and Building Use Considerations

The insulation you choose depends heavily on where your building is located and how it will be used.

For example, coastal areas in Canada face high humidity levels, making closed-cell spray foam or mineral wool batts excellent options due to their moisture resistance. On the other hand, the Prairies experience extreme temperature shifts, ranging from −30°C in winter to +30°C in summer. In such conditions, spray foam stands out for its consistent R-value and airtight properties.

The building’s purpose is just as important. If you’re insulating a simple vehicle storage garage or agricultural barn, fibreglass batts might be enough. Temperature control isn’t as critical in these spaces, and the lower upfront cost makes it a practical choice. However, for workshops, barndominiums, or commercial spaces where maintaining a consistent temperature is key, spray foam is invaluable. Its dual role as an air and vapour barrier makes it a smart investment. Any conditioned space also needs insulation that actively addresses thermal bridging, not just something that fills the gaps.

Think of it this way: If your building is unconditioned, batts will do the job. If it’s conditioned, spray foam is worth the extra cost.

These considerations are essential for selecting insulation that complements your steel building.

Integrating Insulation with Steel Building Kits

It’s crucial to factor insulation into your plans early – ideally during the design and ordering phase. This is especially true when working with steel building kits, as the framing dimensions, purlin spacing, and panel depth all influence which insulation systems will work best.

"The best approach for insulating cold-formed steel framed walls in Canada combines exterior continuous insulation with cavity insulation while carefully integrating air, vapour, and moisture control." – YPP Canada

For instance, if you’re planning to use a high-R-value batt system, your framing cavities need to be deep enough to accommodate the insulation’s thickness. Specifying these details during the ordering process can save both time and money.

A great resource for Canadians considering steel building kits is Canadian Buildings. They offer guidance on customization options, including insulation compatibility, for various building types like garages, workshops, barns, and barndominiums. This can help you integrate insulation into your build plan before construction begins.

Comparison Table: Spray Foam vs Batt Insulation

Feature	Closed-Cell Spray Foam	Fibreglass Batts
R-Value per Inch	R-6.0 to R-7.0	R-3.2 to R-3.8
Thermal Bridging	Eliminated – covers steel frame fully	Frame left exposed; spacers needed
Air Barrier	Built-in	Requires separate sealing
Vapour Barrier	Integrated at 2"+ depth	Requires separate installation
Moisture Resistance	Excellent	Poor when wet; loses R-value
Upfront Cost (30×50 ft building)	CA$3,150–$7,350	CA$600–$1,700
Durability	Permanent; maintains R-value for life	Can sag or compress over 10–15 years
DIY-Friendly	No – professional installation recommended	Yes – no special tools required
Best For	Conditioned spaces, extreme climates, moisture-prone areas	Unconditioned storage, agricultural buildings, tight budgets

Conclusion

Choosing the right insulation is all about finding the balance between performance and budget. Neither spray foam nor batt insulation is a one-size-fits-all solution – it really depends on your specific needs. For example, closed-cell spray foam shines in cold Canadian climates, conditioned spaces, and buildings where controlling moisture is critical. On the other hand, fibreglass batts are a cost-effective choice for unconditioned spaces like storage or agricultural buildings where tight temperature control isn’t a priority.

Since steel is highly thermally conductive, proper insulation is essential to prevent energy loss. Thermal bridging, a common issue in steel buildings, can lead to significant inefficiencies. Spray foam is uniquely suited to solve this problem because it covers the steel frame directly, breaking those thermal bridges and boosting energy efficiency. This is especially important in Climate Zones 5–8, which include most of Canada.

While batts might have a lower upfront cost, spray foam’s longevity and energy efficiency can lead to substantial savings over time. Quality insulation can cut energy use by 25–50% compared to an uninsulated building. The best choice ultimately comes down to your building’s purpose, climate, and the long-term savings you aim to achieve. A workshop in northern Ontario, for instance, will have vastly different insulation needs compared to a seasonal storage shed in southern British Columbia.

Make sure to plan your insulation early – before ordering your kit – to save both time and money.

FAQs

How thick should closed-cell spray foam be in a steel building?

Closed-cell spray foam in a steel building is usually applied at a thickness of 1 to 2 inches. The specific thickness can vary based on your climate zone and what you’re aiming to achieve with insulation. It’s important to factor in local conditions to ensure the best performance and energy efficiency.

Do I still need a vapour barrier with batt insulation in Canada?

In Canada, whether to use a vapour barrier with batt insulation largely depends on the climate and how the wall is constructed. In colder regions, it’s generally advised to have a vapour control layer on the interior side of the wall to stop condensation from forming inside the structure. For steel buildings, combining a vapour barrier with other moisture management strategies – such as continuous exterior insulation and effective sealing – can help improve both durability and energy efficiency.

Can I combine spray foam and fibreglass batts to cut costs?

Using both spray foam and fibreglass batts is a smart way to cut costs while improving insulation performance. This method, often called "flash and batt", involves applying a thin layer of spray foam to create an effective air and moisture barrier. After that, fibreglass batts are added to boost the overall R-value.

This approach works well because it reduces the amount of spray foam needed, which helps keep expenses in check. Plus, it effectively addresses thermal bridging in steel buildings by sealing the framing and adding an affordable layer of insulation. It’s a practical solution that balances cost and efficiency.