How does spray foam insulation work

How does spray foam insulation work

As homeowners, people face a lot of difficulties insulating their homes to lower their energy bills and increase overall comfort. That’s why it is extremely important to choose the right kind of insulation in your house. One of the best kinds of insulation money can buy is spray foam insulation. But how does spray foam insulation work?

Spray foam insulation is a mixture of two kinds of chemicals. These chemicals are mixed on the spot and create a foam that hardens as soon as it applies. Once applied on a surface, the foam covers every bit of area of the surface, and every hole and crevice is covered by it. As a result, heat, wind, and moisture can not pass through the barrier created by the foam and keeps the home properly insulated. 

Let’s take a deeper look at the working procedure of spray foam insulation. 

Working procedure of Spray Foam Insulation

Nowadays, spray foam insulation is very common in houses all over the world, as they are replacing fiberglass and cellulose quite quickly. But what is the cause of such an increase in their popularity?

To know this, we must first understand how spray foam insulation works and what is spray foam insulation made of.

Spray foam insulation, which is industrially known as Spray Polyurethane Foam or SPF, is actually a mixture of two substances. These two substances are MDI (Methyl Diphenyl Diisocyanate) and various Polyols. When these two chemicals mix, they instantly form a foam that we know as SPF. 

MDI (Methyl Diphenyl Diisocyanate) and various Polyols

One of the unique spray foam insulation properties is that it spreads and hardens as soon as it is applied on a surface. So when the experts use this mixture, the foam keeps spreading and hardening, occupying every nook and cranny of the wall, roof, or loft. This creates a barrier that doesn’t allow any heat, air, or moisture to pass through.

How many layers of spray foam insulation you will need to apply on a surface depends on what kind of SPF is being used on it. There are two types of spray foam insulation out there. They are:

Open-cell SPF

Open-cell SPF is applied to various open spaces on the building envelope’s surface. They are cheaper than the closed-cell SPF which we will discuss in just a minute.

Once applied, their volume increases almost 100 times and they seal off the open cavities on the surface. They are also a lot flexible, so even if the surface moves around a little, they allow it to happen without cracking or damaging the surface. As they are thinner, you need to apply multiple layers of them.

They also provide better sound and air barriers, so if you want to keep your home calm and free of noise, open-cell foams should be your go-to SPF. But there are some disadvantages as well since open-cell SPF has a lower thickness, they have a lower moisture resistance. Also, due to their greater flexibility, they are not very strong. 

Closed-cell SPF

Closed-cell foam insulation is applied with a spray foam insulation kit onto the surface to seal off any open pores or cavities on it. Once applied, they keep expanding and hardening until they seal off every cavity they find.

They are thicker than their counterparts and have greater moisture resistance. You don’t have to put that many layers of closed-cell SPF on a surface. 

Unlike the open-cell foams, they are quite durable, so if you leave them open, they won’t be damaged right away. They are also very thick, which provides greater rigidity than open-cell foams. But there are some drawbacks to using closed-cell SPF as well. The first of these is the price. Closed-cell spray foam insulation is costlier than open-cell one. 

The spray foam insulation cost for open-cell SPF is between $0.44 and $0.65 per board foot, while that of the closed-cell SPF is between $1.00 to $1.50. Also, due to greater rigidity, the closed-cell SPF allows for less flexibility. It also doesn’t repel sound as well as open-cell foams.

What are the benefits of spray foam insulation?

There are a whole host of benefits to using spray foam insulation in your homes. They are:

Increases Energy Efficiency:

One of the main goals of insulating your home is to ensure it is energy efficient. Since the SPF creates an air barrier, it doesn’t allow heat to get into the house during summer, while also keeping cooler air out during winter.

As a result, the home remains cooler when it is summer, and warm when winter comes around. This allows you to minimize the use of various electrical appliances such as fans, AC units, heaters, etc. This ensures your energy consumption is kept to a minimum and your house is an energy-efficient one. 

Ensures maximum comfort:

If a house is not properly insulated, the heat during summer and cool air during winter come in contact with the air inside the house, warming up and cooling down the home’s interior respectively. This is extremely uncomfortable for the inhabitants of the house.

Insulating with spray foam insulation ensures the air and heat outside don’t come in contact with the interior air of a house, making it very comfy for people to live in. 

Prevents Water Damage:

One of the biggest issues houses face is the damage caused to the walls and roofs due to coming in contact with water. Not only does water damages the materials of the walls and roofs, but it also causes mold top to grow in the house, which is a major health hazard, causing respiratory diseases. 

Since spray foam insulation creates a seal, water is absorbed by the foam, so it can not come in contact with the wall or roof. SO water damage is minimized and the growth of mold is stopped completely. 

Blocks out the noise:

Sound needs a medium for it to be able to pass. But as the air can’t pass through the spray foam-created air seals, noise coming from outside is greatly reduced. This makes the home increasingly quiet and calm. 

Increases home value:

If you want to sell your home, then there’s no better insulation choice than SPF. As it blocks out noise, heat, and cold, prevents water damage and makes the home comfortable, the value of the house increases by a lot. This allows you to sell your home at a better price. 

Final Words

If you are new to the concept of spray foam insulation, you might often wonder, “How does spray foam insulation work?” But once you see how our experts work, you will be able to see how it is prepared and how its working procedure. Contact us to know more about SPF and to insulate your home with it. 


1. Is spray foam insulation safe?

Spray foam insulation is in most parts, safe. But it depends on by whom it is being installed. If an unlicensed individual installs the SPF, then it might cause some structural and health issues down the line.

2. What is the spray foam insulation mortgage problem?

Although spray foam insulation has a lot of upsides, it is a serious issue when it comes to getting a mortgage. This is because when the insulation restricts airflow, it can cause condensation, rotting the wood in the process.

Using closed-cell SPF can also cause the structure to crack, break or warp. These make a house risky as an investment, so the mortgage is refused. 

3. What are the disadvantages of spray foam insulation?

There are a few disadvantages of spray foam insulation that makes homeowners have second thought before installing them. First, they can be quite costly, especially when compared to fiberglass.

Also, you can rarely install the SPF by yourself, unless it is a very small job. So the cost keeps rising. Additionally, using SPF causes the mortgage to be denied.