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Why Spray Foam is The Best Insulation for a Barndominium?

Spray foam is considerably the best insulation for a barndominium.

But why?

We know that there are 5 more types of insulation and there are a few reasons that make spray foam your ideal choice as an insulating material.

In this article, we will try to examine those reasons and will justify the grounds that made spray foam so popular as the top-notch barndominium insulator.

Why does insulation matter?

Proper insulation for a house in USA (or in other countries) is crucial for the following reasons:

  • Insulation protects the house temperature from sudden or abnormal deviation by changes in outdoor ambiance.
  • It offers weatherproofing which directly contributes to the durability of the house, and the wellbeing of the family members and protects the steel frames from corrosion.
  • Proper insulation ensures energy efficiency by reducing the use of heating or cooling appliances as it aims to protect indoor temperature for the longer term.
  • To noise-proof a house, insulation plays a vital role. Insulators such as cellulose, fiberglass, and spray foam create a noise-proof boundary that effectively helps especially for the steel structures.
  • Proper insulation blocks outdoor moisture from entering into the home which is an essential safeguard for the allergic people since it reduces molds and fungus.
  • More importantly, proper insulation would offer you a tax credit because you are saving energy by keeping the indoor temperature constant. As per the tax authority, you may receive upto $1,200 or 30% of the insulation cost if you insulate as per the authority’s guideline.
  • Last but not least, good insulation will always keep the future resale value high as the future owners would not prefer to reinvest in insulation.

What is spray foam insulation?

Spray foam insulation is a type of insulation with maximum resistance to the outdoor temperature. In this process, a mixture of isocyanate and polyol resin is sprayed onto the wall and floor which creates a polyurethane foam barrier.

More importantly, spray foam is the only insulator that creates expansion after spraying (like shaving foam). Such minor expansion helps to cover tiny areas that can not be seen with the naked eye. By covering a lot of hidden areas, spray foam ensures that there is not a single gap uninsulated especially on the wall. Due to its nature, this insulation offers air sealing which is highly essential for the homes in USA.

Spray foam insulation advantage

Types of spray foam

There are two types of spray foam insulation: open-cell and closed-cell.

Open-cell spray foam is much more flexible and dense compared to closed-cell spray foam. Open-cell foams offer considerably good insulation but are not capable of offering a water vapor barrier.

Also, open-cell spray foam is cheap, which is why it is used as insulation for indoor walls as it creates a heavy noise barrier. Alternatively, open-cell spray foam is a very good choice as a soundproofing material.

In contrast, the closed-cell spray foam is much more rigid and offers a greater R-value. The R-value measures how strong the insulation can resist the outdoor temperature deviation.

Open cell vs closed cell spray foam insulation

More importantly, the closed-cell spray foam creates greater thermal resistance and fills air gaps. Filling up the small air gaps helps in securing the house free from moisture and water vapor. And this is why closed-cell spray foam insulation is widely preferred for outdoor wall insulation.

Why spray foam insulation is popular for banrdominium?

Spray foam (especially closed-cell insulation) is the most popular insulator for barndominium due to the following reasons:

  • Spray foam offers the highest R-value which helps to comply with the building codes.
  • This is energy efficient compared to other types of insulation.
  • It suits floors, walls, and other areas due to its flexible nature. As a reference, other insulators such as blanket insulation or rigid foam come in shapes and you need to match the shape by cutting or squeezing.
  • Spray foam insulation is easier and effective for window and door gaps which is impossible with other insulators, except for the blown-in insulation.
  • Open-cell spray foam offers an R-value of R-3.2 per inch and the closed-cell spray foam offers even R-6 which is considered to be the highest R-value among the peers.
  • Spray foam insulators create air, sound, and moisture barrier. Such comprehensive insulation advantage is impossible with other types of insulators such as blown-in insulation or rigid foam.
  • Due to becoming more rigid, the closed-cell spray foam reinforces the structural strength which is a plus point.
  • Spray foam lasts longer than other types of insulation. For instance, the closed-cell spray foam would last about 20 to 30 years whereas the fiberglass insulation would last around 10-20 years and the cellulose insulation would last for 15 to 30 years. More importantly, neither the fiberglass nor the cellulose would give you the moisture barrier and extended air sealing.
  • Lastly, spray foam would create better indoor air since it clocks all the moisture and water vapor.
Spray foam insulation key takeaways

Open-cell vs closed-cell foam insulation

Let’s explore the core differences between open-cell spray foam and closed-cell spray foam insulation.

  • From the structural point, the open-cell spray foam is more flexible than the closed-foam. This is why the open-cell foams are used in indoor walls and the closed-cell spray foam is applied on the outdoor walls. So, closed-cell spray foam will eventually strengthen your structure.
  • Closed-cell spray foam offers double R-value than the open-cell spray foam. For example, the closed-cell foam offers R-value of R-6, and the open-cell foam delivers R-3.2 roughly.
  • Closed-cell spray foam is rigid and more stronger which is the main reason of creating a moisture barrier.
  • Closed-cell foams are more expensive than open-cell foam.

So, these were the overall differences. But, only based on the differences you cannot consider one good and the other bad. Both are top-notch insulation just applicable in different aspects depending on climate and structural strength.

How much does spray foam insulation cost for barndominium?

The cost of the spray foam insulation varies depending on the factors such as:

  • Size of the barndominiu
  • Thickness of the foam
  • Type of spray foam (open-cell or closed-cell)
  • Regional labor costs.

Let’s give you an idea about their costs.

Open-cell spray foam is cheaper. It would cost around $0.35 to $0.55 per board foot (one board foot is a square foot that is one inch thick).

In contrast, closed-cell spray foam insulation is more expensive. It costs around $1.00 and $2.00 per board foot.

Let’s take a hypothetical example: for a 2,000-square-foot barndominium with a 10-foot ceiling, you’d have 20,000 board feet. If you decide to insulate with open-cell foam, the insulation could cost between $7,000 and $11,000. If you choose closed-cell foam, it could cost between $20,000 and $40,000.

Disclaimer: The cost is an approximate figure and may not match your local vendors’ quotation. Furthermore, these costs are subject to change in other variables such as season, location, cost of raw material, and so on.

So, it is important to receive quotations from multiple vendors and cross-varify among them.

When can you choose other insulation over the spray foam?

These are the situations when the spray foam may not be a suitable option for you.

  • If you are targeting DIY insulation
  • If you have budget constraints
  • When you do not need stronger thermal resistance
  • When the local building code does not demand for stringer R-value
  • If you need to move the insulation from one home to another, batt insulation can be preferred over the spray foam


If you are building a metal barndominium, we strongly suggest using closed-cell spray foam insulation. It might cost you a little bit high but the future return would be much greater than what you are paying now.

If your barndominium is located in an area with less weather volatility, you may try installing other insulation such as batt or rigid foam. But always remember, only the spray foam would offer you moisture protection, not anything else.

Brian Cooper
Brian Cooper

I'm Brian, an architectural engineer from the University of Texas

Writing about barndominium is my passion. I try to bring informative and technical contents on barndominium so that the entire sourcing and construction process seems easy.

As an architectural engineer, I do have expertise of designing and building using prefabricated steel structures. Moreover, I am connected with 500+ prefabricated steel structure experts that helps me to gather and prepare the relevant information for your help.

I have experience of 250+ barndominium contrustion of which 75% are built with metal structure. Moreover, I am a trained energy audit professional, and with that specialization I can help you to bring your barndo's energy consumption at minimum level.

I hope you like my write-ups which is my greatest inspiration.

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