Foam Board vs Spray Foam Insulation: A Detailed Comparison

When it comes to insulating your home, you have plenty of options to choose from. One option, foam board insulation, has some clear benefits compared to other insulation materials, while another type of insulation, spray foam insulation, may offer even better results. 

So, which material is the best option? Keep reading to find out more details of each insulation material and how they stack up against each other. This information will help you choose between them based on what’s most important to you and how much you want to spend on your insulation project.

Spray Foam InsulationFoam Board Insulation
Usually made with polyurethaneMade with either polystyrene, polyisocyanurate, or polyurethane
Easier to install. Polyurethane comes as two liquid sprays. When applied, it expands and solidifies into a thick foamy layer A bit difficult to install in comparison. Usually available in 4×8 foot sheets with ¼ to 2 inches thickness and can be cut to fit in different spaces
Can be used in hard to reach places and around pipes to seal holes and cracksMostly used for insulating exterior walls, especially basement walls
Has a higher R-value of 5 to 6.5 inchesIts R-value ranges from 3.6 to 5 per in
Provides perfect insulation by sealing challenging corners, cracks, and holes Cannot provide airtight insulation on its own and may need spray foam or other insulations to seal the joints and cracks
Highly resistant to flood water damage. Class 4 material on FEMA listHighly water-resistant but needs higher-density foam boards for below-grade installation
Spray foam vs foam board insulation
spray foam insulation
Spray foam insulation
a room full of rigid foam insulation
Foam board insulation

Comparison between foam board and spray foam insulations

Spray foam insulation and foam board insulation are designed to keep your home warm in the winter and cool in the summer. Each has its own set of benefits that may make it more desirable than the other, depending on your needs. However, spray foam insulation has some great benefits over foam board insulation, including fewer installation steps and more versatility of use, but it’s also more expensive upfront.

Let’s see how they compare with each other!

Insulation Efficiency

Both spray foam and foam board insulation come with impressive thermal insulation scores. It’s hard to pick a clear winner here as both products give you excellent R-values and are very energy efficient. However, one key point influencing your buying decision is that a crack or gap between the foam boards can affect its whole insulation performance. On the other hand, spray foam efficiently seals all holes and cracks.

Installation methods

One of spray foam’s greatest assets is its ease of use as you simply spray it into a cavity where it expands and solidifies to fill any holes. But it is a messy process and needs lots of cleaning afterward. One thing worth mentioning here is that you need protective clothing and a full-face supplied air respirator when working with spray foam insulation. So, it’s more logical to hire an experienced professional to do the job instead of DIYing. 

In comparison, installing foam boards is very straightforward as it only needs cutting the boards to fit in specific places. Also, there isn’t any mess during installation compared to spray foam application. 

Usage flexibility

Foam board can be used only in limited spaces because of this rigidity but still has many uses in the insulation planning for many homes. Compared to that, spray foam is more flexible insulation with many uses while insulating a home.

Moreover, spray foam fills in gaps between building materials, making for a more energy-efficient and quieter home. It can also cover large surfaces like ceilings and walls to save on installation costs. It means spray foam can be efficiently used in large and small areas such as tricky corners and even around pipes. So, if you’re looking to fill multiple crevices in your home, then it pays to use spray foam insulation. Plus, homeowners will love how it improves their resale value when planning on selling their homes later.

R-value per inch

Spray foam insulation typically boasts an R-value of 5 to 6.5 per inch, as opposed to foam board with an R-value of 3.6 to 5 per inch. It requires less material to do its job because it expands during installation and fills any cracks or crevices in your walls. Spray foam weighs only 2 pounds per cubic foot. Also, its medium-density makes it a valuable part of any successful air sealing strategy.

Similarly, foam boards also have an impressive R-value, though not equal to spray foam, making them suitable for many applications.


Spray foam provides an airtight barrier between your living space and outdoor temperatures. It works as a thermal break that helps keep heat inside during cold weather and keeps heat outside during warm months. Additionally, its airtight seal also reduces moisture levels in your home, making it an excellent choice for moisture-prone areas. The reduced moisture means you’ll see fewer molds, mildew, and pests like termites.

Contrary to spray foam, foam board insulation doesn’t provide airtight insulation on its own. Using spray foam on the joints and gaps provides more airtight and effective insulation in many areas.

Water resistance

Spray foam is made of closed-cell polyurethane, which makes it very strong. It is a class 4 material that is resistant to flood water damage. No other cavity insulation has made it to this list from FEMA (Federal Emergency Management Agency).

Likewise, foam board is also very much water-resistant, even though not on the level of spray foam insulation. So, if you are using foam board insulation in a flood-prone area, go for higher-density boards to minimize water damage.

Fire Resistance

Unlike fiberglass or cellulose, which is flammable, closed-cell spray foam provides excellent fire resistance. During manufacturing, closed-cell spray foam insulation is treated with fire retardants and has a class 1 fire rating making it a highly fire-resistant insulation material.

Foam board manufacturers are also adding fire retardant to the foam boards, reducing the chances of fire hazards.


Both spray foam and foam board are incredibly durable but in different ways. A layer of spray foam is slightly thicker than a layer of foam board, which means it will probably last longer. Foam board can also last more than a hundred years if external factors don’t make it deteriorate. So, if you plan to move within a few years, you can rest assured that these insulations will for quite a long time!


In terms of cost per square foot, spray foam costs more than traditional insulation and foam board insulation. Plus, you will need an insulation professional to do the work, which will increase the overall cost. However, this investment is worth it as spray foam insulation will reduce your energy bills, especially during winters, by eliminating the heat loss from your home.


Foam board insulation and spray foam insulation are two of the most popular insulation choices available on the market today, and people often wonder which one they should choose. Both foam board and spray foam insulation are solid home insulators. The better option depends on what you are building and your personal preferences. 

If you’re looking for an affordable way to improve your home’s energy efficiency, foam board insulation is a great option. Best of all, foam board insulation provides permanent, adequate protection against drafts and heat loss. However, spray foam insulation has a few advantages over foam board.

Each type of insulation has its advantages and disadvantages, which are outlined in this detailed comparison above so you can make an informed decision.

Charles John

Experienced HVAC technician with 8 years of experience in the industry. Capable of handling all sorts of heating and cooling equipment as well as proficient in operational management, construction-related techniques such as preventative maintenance, electrical troubleshooting and AutoCAD

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