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What is Open Cell Spray Foam Insulation? What it’s Made of, How it Works, & More

spray foam insulation

What is Open Cell Spray Foam Insulation? What it’s Made of, How it Works, & More Blog Feature
Amanda Ringler

By: Amanda Ringler on September 30th, 2020

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As a homeowner, you are looking into new or updated insulation for your home. However, you still have questions about open cell spray foam.

With more than 17 years of experience insulating homes across Michigan’s lower peninsula with spray foam, RetroFoam of Michigan can answer all your questions about open cell foam insulation as well as its benefits as an insulation material.

We're on a constant mission to educate homeowners on all things spray foam insulation. As part of this mission, we will discuss what open cell foam is, what it's made of, and how it works.

What is Open Cell Foam?

Open cell spray foam is a very pliable, light-weight insulation material best suited for attics, rim joists, crawl spaces, or open wall cavities.

A few other qualities of open cell spray foam include its sound dampening qualities, the air seal it creates, and that its blowing agent is water.

As an insulation material, open cell spray foam is known to maintain a constant home temperature while creating an air seal. This helps in reducing monthly energy bills as the air conditioner and furnace don't run constantly.

How Open Cell Foam Insulation Works

Open cell spray foam helps to improve the energy efficiency in the home by filling in gaps and cracks while expanding 100 times, thus limiting air loss.

This expansion fills all of the nooks and crannies, preventing air movement where the spray foam has been applied.

The insulation material can also play a role in moisture management. It allows leaks to move through it so the trouble areas can be identified and fixed. It also helps to reduce the occurrence of ice dams and also limits the air leakage through the attic.

Not only does it help minimize air leaks, but open cell spray foam insulation also helps to maintain an even temperature throughout the home where it has been applied, making the space more comfortable.

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What Open Cell Spray Foam Has to Offer

Open cell spray foam insulation is more than just an air barrier and insulating material. Here is what open cell has to offer.

  • Open cell can be installed at a lower cost while providing the same coverage as closed cell.
  • Open cell will accommodate seasonal movement, so when your house shifts and settles the foam will move with it.
  • The spray foam allows water to move through it without retaining it or losing insulation properties.
  • It has vapor permeability.
  • Open cell spray foam cannot sustain mold.
  • Its blowing agent is water.
  • Open cell has sound dampening qualities.

Open Cell vs Closed Cell Foam Insulation: What is the Difference?

There are two types of spray foam insulation offered here at RetroFoam of Michigan -- closed cell and open cell spray foam.

  • Open cell spray foam outperforms traditional insulation like fiberglass and cellulose. Open cell provides high-performance thermal insulation and air sealing. The material can also provide a sound barrier. Another bonus of open cell spray foam insulation is it allows leaks to drain through, letting you identify trouble spots sooner for repair. A safety feature of open cell is it typically uses water as its blowing agent.
  • Closed cell spray foam is made to be a tougher insulation. This rigid spray foam performs great in flood-prone areas since it can reject bulk water. Closed cell spray foam insulation uses a chemical agent that can put off a temporary odor.

What is Open Cell Spray Foam Insulation Made Of?

Spray foam insulation is a more modern and energy-efficient way to keep homes cool in the summer and warm in the winter. It also reduces sound transmission while minimizing air loss.

But what exactly is it made of?

Open cell spray foam insulation is a combination of two liquids – a polyisocyanurate (ISO) and a resin. The two compounds are kept separate until it’s time to use them. They are then sprayed onto a surface, creating the foam product.

Spray foam insulation is made when:

  • Two liquid components (ISO and resin) are mixed together. The components are mixed at the site where the insulation will be installed. The two liquids come in different drums or containers and are usually referred to as container “A” and container “B.”
  • The “A” container is usually made up of methylene diphenyl diisocyanate and polymeric methylene diphenyl diisocyanate.
  • The “B” container is typically a blend of polyols, catalysts, blowing agent, flame retardant, and surfactants.
  • The reaction of the “A” and “B” happens when the two are combined and, in a matter of seconds, expands to create the foam.
  • The foam then seals the gaps and forms a barrier wherever it is applied.

The “A” container and “B” container are both proprietary to each spray foam manufacturer. Most “A” barrels will share components, but each manufacturer will have its own proprietary blend.

What is the Process of Installing Open Cell Spray Foam?

Once a homeowner has received an estimate and signs a contract, the work is ready to begin.

In most cases, RetroFoam of Michigan uses open cell spray foam insulation in the attic, exposed walls, crawl spaces, rim joists, and in pole barns and concrete block walls.

In an existing home, the day before installation, a crew will come to the house to remove any old insulation in the area that is to be insulated. A good contractor will remove the insulation and dispose of it for the homeowner.

On the day of installation, crews will prep the area where the spray foam will be installed. This includes moving furniture and other large items to the middle of the room, then covering them in plastic. Any surfaces and flooring are also covered to ensure the foam doesn't end up any place it's not supposed to be.

After the prep work is complete, the crew will run a hose to the area that is to be insulated. They will then suit up and begin spraying the areas. When the team is finished, they will clean up the area, so it looks just like it did before the work started.

How Does Open Cell Spray Foam Insulation Affect Energy Cost?

About 40 percent of energy cost comes from heating and cooling your house as air is leaking out, according to the Department of Energy.

That is just like leaving one window open in your house for 24 hours a day all year long.

Only spray foam insulation protects against the single biggest source of heat flow – air leakage – because it forms an effective air barrier.

Getting Started with a Free Estimate

You’ve now learned all there is to know about open cell spray foam insulation and are a step closer to deciding what is the best material for your project.

If you live in Michigan’s lower peninsula or the greater Toledo area and are ready to schedule a free in-home estimate give us a call at 866-900-3626, or fill out the form on our website.

You can also check out our budget calculator to give you a rough idea of the cost to insulate your home or pole barn.

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About Amanda Ringler

Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor in Flint and Detroit. Throughout her career as a journalist, she has won several awards from The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. As part of the RetroFoam of Michigan family, Amanda uses her experience as a journalist to write content that will help educate homeowners on the benefits of foam insulation. When Amanda isn’t writing, she’s spending time with her husband and rescued huskies. She also loves knitting, making art, cooking, and hosting dinner and a movie night for friends and family.