What Is Foam Board Insulation and How Much Does It Cost?

By Elizabeth Michael

October 22, 2026

If you've noticed a not-so-pleasant musty odor in your home (particularly your basement or other rooms with concrete walls) but there's no sign of a water leak, it may be a good time to install foam board insulation.

This May Also Interest You: How to Use Insulation to Save Energy and Money

When humid air touches cold concrete, it can create moisture and trigger mold growth. Foam board insulation solves the problem by creating a barrier that stops condensation in its tracks, and it can cost anywhere from around $3,400 to $6,750 (CAD 4,849 to CAD 9,626) or more to install.

What Is Foam Board Insulation?

Foam board insulation consists of rigid, preformed plastic panels that resist heat and moisture. Unlike flexible insulation materials, foam board is installed as solid sheets, making it an ideal option for exterior sheathing, basement walls and roofs. Here's a breakdown of how foam board insulation differs from other insulation types:

How Is It Different From Fiberglass Insulation?

Crafted with fine glass fibers, fiberglass is flexible, cheap and easy to install in standard wall cavities. However, it tends to sag over time, which can reduce its overall effectiveness.

How Is It Different From Spray Foam Insulation?

Applied as a liquid that expands into a thick, airtight seal, spray foam fills every nook and cranny. Spray foam contains some plastic materials similar to foam board, but foam boards are rigid panels while foam is a flexible liquid.

How Is It Different From Batt Insulation?

Consists of pre-cut fiberglass or mineral wool blankets designed to fit securely between framing studs. Batt insulation is a low-cost option that's best suited for do-it-yourself (DIY) projects, while foam insulation sheets offer superior rigidity and higher insulation value per thickness.

How Much Does Foam Board Insulation Cost to Install?

On average, foam board insulation costs $2.20 to $4.50 (CAD 3.14 to CAD 6.42) per square foot and $3,400 to $6,750 (CAD 4,849 to CAD 9,626) or more to install. Factors that can affect pricing include your home's square footage, overall board thickness and the total insulation coverage area.

What Are the Main Types of Foam Board and How Do They Differ?

Foam board insulation comes in three main types, each made of different plastics and offering varying levels of moisture protection and insulating power. Here's a look at the different types.

Expanded Polystyrene (EPS)

Similar in look and texture to a plastic foam coffee cup or cooler, EPS has the lowest insulating power per inch when compared to its counterparts.

Extruded Polystyrene (XPS)

Commonly found in hardware and home improvement stores, XPS blocks water more effectively and offers better insulating power than EPS.

Polyisocyanurate (Polyiso)

Offering the highest insulation power per inch, Polyiso is typically utilized in commercial buildings and structures that require maximum warmth without extra thickness.

More Related Articles:

What R-Value Does Foam Board Insulation Offer?

R-value (thermal resistance) is a measurement of how well insulation resists heat flow. A higher R-value number means better performance. For example, foam board insulation typically has an R-value of R-4 to R-6.5, depending on the specific insulation type. The thicker the board, the higher the R-value.

Is Foam Board Insulation Waterproof/Moisture-Resistant?

Unlike regular fiberglass, foam board is highly waterproof and moisture-resistant, meaning it won't sag or become soggy when it comes into contact with water or moisture. All three types of foam board (EPS, XPS, Polyiso) are considered heavy-duty water blockers, and their materials won't crumble when wet.

Is Foam Board Insulation Fire-Resistant, or Does It Need a Fire Barrier?

No, foam board insulation is not fire-resistant. Since it's made of plastic, it can easily melt or catch fire when it comes into contact with a spark, flame or heat. It always requires a fire barrier, such as a layer of regular drywall, to eliminate fire risk and protect homes.

All CAD conversions are based on the exchange rate on the date of publication.

Follow us