Spray Foam vs. Rigid Board: Which One Wins for Maximum Energy Efficiency?

When it comes to insulating your home or building, two of the most talked-about options are spray foam insulation and rigid foam board. Both have their place — but if you’re aiming for long-term performance, airtightness, and serious energy savings, spray foam takes the crown.

Let’s break down the differences, where each works best, and why spray foam is the smarter choice for most Nova Scotia homes.

🧱 First Things First: What Are They?

Rigid foam board insulation (often called “rigid board” or “foam board”) comes in large, flat panels made from polystyrene, polyisocyanurate, or polyurethane. It’s commonly used on exterior walls, under slabs, or in certain retrofit projects.

Spray foam insulation, on the other hand, is applied as a liquid that expands into a thick, seamless layer — sealing every crack, gap, and cavity it touches.

It comes in two main types:

• Closed-cell foam: Dense, strong, and acts as both an insulator and moisture barrier.

• Open-cell foam: Softer and more flexible, great for interior walls and soundproofing.

Both materials insulate, but how they perform is where things really start to differ.

💨 The Airtightness Factor (Where Spray Foam Shines)

Rigid boards can deliver good R-values per inch — but they don’t air seal. Every board has seams, and every seam can leak air unless it’s perfectly taped or foamed around. Over time, those joints can shift, crack, or pull apart slightly, creating small gaps where air sneaks in or out.

Spray foam, on the other hand, is completely seamless. It expands to fill every void, creating an airtight barrier that prevents drafts, moisture infiltration, and heat loss all in one step.

That means no taping, no gaps, and no thermal bridging. Just pure, continuous insulation from top to bottom.

✅ Winner: Spray Foam — by a long shot.

⚡ Energy Efficiency and R-Value

Rigid foam boards typically have an R-value of R-4 to R-6 per inch, depending on the type. Closed-cell spray foam, meanwhile, delivers around R-7 per inch — but that’s not the whole story.

Because spray foam also air-seals as it insulates, the effective R-value of your entire wall or attic system is much higher. Rigid board may look good on paper, but if air is moving behind

or between panels, those numbers drop fast.

✅ Winner: Spray Foam — real-world performance beats theoretical numbers every time.

🧊 Moisture & Weather Resistance

Here in Nova Scotia, moisture is no joke — between ocean air, humid summers, and cold winters, insulation needs to handle it all.

Rigid board can absorb moisture around edges and seams if it’s not perfectly sealed. Over time, this can lead to reduced performance, mold growth, or even rot if it’s installed against wood framing.

Closed-cell spray foam, however, is completely moisture-resistant. It creates a vapor barrier that keeps humidity and condensation out — ideal for basements, rim joists, and coastal homes.

✅ Winner: Spray Foam — especially in Maritime climates.

🔧 Installation and Long-Term Durability

Rigid board needs to be cut, fitted, and sealed with tape or spray foam around every joint. It’s time-consuming and easy to install imperfectly (especially on irregular surfaces).

Spray foam, on the other hand, adapts to any surface — stone, wood, steel, or concrete — and creates a tight, uniform layer. It won’t sag, shift, or deteriorate over time, meaning it performs just as well in year 20 as it does on day one.

✅ Winner: Spray Foam — fast install, lifetime performance.

🏡 Real-World Impact: Comfort You Can Feel

A lot of homeowners don’t realize how much a proper air seal impacts comfort until they experience it.

Spray foam helps:

• Eliminate cold drafts and uneven room temps

• Reduce outside noise

• Keep humidity levels balanced

• Make your HVAC system run more efficiently

Rigid board might insulate, but spray foam transforms how your home feels. That’s something you’ll notice every single day.

✅ Winner: Spray Foam — comfort you can literally feel.

💰 Cost vs. Value

It’s true — spray foam can cost more upfront than rigid board. But when you factor in:

• Reduced energy bills (often 30–50% lower)

• Long-term durability

• No need for additional air sealing

• Possible Efficiency Nova Scotia rebates

…the numbers start to balance out fast. In most cases, spray foam pays for itself within just a few years.

✅ Winner: Spray Foam — better investment, bigger savings.

🌿 The Final Verdict

Rigid board has its place for exterior applications or certain building assemblies, but when it comes to whole-home energy efficiency, airtightness, and long-term comfort, spray foam insulation wins hands down.

It’s the smarter, cleaner, and more effective way to insulate — especially in Nova Scotia’s unpredictable climate.

✅ Ready to Upgrade Your Home’s Efficiency?

If you’re ready to say goodbye to cold drafts and rising energy bills, our team can help. We specialize in closed-cell spray foam insulation for attics, basements, crawl spaces, and full-home upgrades across Nova Scotia. As proud partners with Efficiency Nova Scotia, we’ll even help you access rebates to make your project more affordable.

📱 Call or text: 902-918-0405

📧 Email: sales@sprayfoamsquad.ca

🌐 www.sprayfoamsquad.ca