Everything You Need to Know About Injection Foam Insulation For Your Home

Insulation is crucial for eliminating drafts and maintaining a consistent temperature in your home. With properly installed and highly effective insulation, you’ll see a reduction in energy bills, can keep out unwanted outdoor noises and allergens, and even fireproof your home. One of the most effective types of insulation that checks all these boxes (and more) is called injection foam insulation.

But what is injection foam insulation, and how do you install it? Below, we’ll explore everything you need to know about injection foam insulation.

Key Characteristics of Injection Foam Insulation    

Injection foam insulation is a type of foam insulation that can fill cavities in existing walls. Unlike other types of foam insulation, injection foam doesn’t expand much, which means you can fill cavities entirely without worrying about the expansion pressure later cracking or damaging the walls.

Injection foam has a consistency similar to shaving cream and takes about 24 hours to harden. Only professionals should install this material, which is ideal for hard-to-reach nooks and crannies between wiring and piping.

Injection foam has a high R-value (between R-4 and R-5 per inch), which makes it highly effective at maintaining interior temperatures and eliminating drafts.

The Benefits of Injection Foam Insulation

There are several advantages to installing injection foam insulation in your home, including:

• Effectiveness as an insulator: Injection foam insulation is one of the most effective types of insulation on the market. It creates an amazing air seal that maintains interior temperatures without forcing your AC and furnace to constantly run. Injection foam companies claim you can reduce your energy bills by up to 50% after installation.

• Soundproofing and fireproofing: While the core objective of installing injection foam insulation is to create an air seal to stop drafts and slow heat transfer, injection foam is also an excellent soundproofing material. Even more importantly, the material acts as a fire barrier that will slow the spread of flames if your house catches fire.

• Air quality improvement: Injection foam also serves to keep out unwanted allergens and pollutants, improving the interior air quality of your home.  It’s also a moisture barrier, meaning you don’t need to worry about mold and mildew growth.

• Clean installation: While you’ve got to leave the installation to the pros, the process is fast and clean. In most cases, all the work is done outside the home, so there’s no need to clear rooms and ventilate the house while the contractors work.

The Disadvantages of Injection Foam Insulation

You’ll also want to consider some downsides to injection foam insulation, including:

• The high cost: Injection foam is one of the most expensive insulation materials. You’ll need to budget double or even triple the cost of other insulation types. However, its superior effectiveness as an insulator could pay off in the long run through reduced energy bills.

• The installation: While the installation is mess-free, it’s also complex and dangerous. You’ll have to call in a team of pros to do this work.

• Not ideal for new construction: Injection foam is designed to fill existing, closed wall cavities. You won’t be able to use this material if insulating a new construction home that is currently being built.

Insulation Types Comparison

Injection foam insulation is just one of many types of insulation. It’s most similar to spray foam, but there are still some key differences between injection foam and spray foam insulation.

Injection Foam vs. Spray Foam

Injection and spray foam are both designed with air sealing and thermal locking properties, but where they are used and how they are installed differ. 

Spray foam is composed of isocyanate and polyol resin, which react when mixed—creating an expanding foam that fills the area it’s applied to, which then hardens to create a seal. This seal protects against thermal transfer and air leakage. Spray foam is designed for use in open cavities and is most often applied in new builds and then covered with another material like drywall.        

Injection foam does not expand, making it suitable for filling closed cavities. It can be used to fill small areas and is often used in the nooks between pipes and wiring. Injection foam can be installed from your home’s exterior so you won’t need to open any walls or tear down any drywall.

Safety and Health Considerations of Injection Foam Insulation

Once injection foam is installed, it’s a very safe material to use as insulation. In fact, it can slow the spread of flames in the event of a fire, keep out unwanted allergens and pollutants, and does not encourage mold and mildew growth.

The material is dangerous during installation, however. Professionals will wear proper safety gear when installing injection foam, which happens outside where it’s safer to breathe.

How Injection Foam Insulation Is Installed

Photo: corlaffra / Adobe Stock

Installing injection foam insulation is a complex process that involves drilling into siding, using special (and expensive equipment) and exposure to hazardous chemicals. Incorrect installation can be ineffective and even dangerous in the long term. That’s why you’ll need to contact a spray foam insulation company near you to handle the work—this is not a DIY project.

Still want to know how this insulation is installed? Here are the basic steps your contractor will take to inject foam insulation into your wall cavities:

1. The Pros Will Mix the Insulation on Site

When the contractors arrive, they’ll mix a fresh batch of the injection foam. It’s important to mix it right before installation, as it will harden within 24 hours.

2. Contractors Will Remove a Strip of Siding

This step depends on what type of siding you have. In homes with vinyl or aluminum siding, the pro will simply remove a strip to access the sheathing beneath. They can then drill holes into each wall’s stud cavities.

For homes with brick walls, contractors will drill into the mortar joints to access wall cavities. If the home has non-removable wood siding or concrete blocks, the contractor will drill directly into the wood or concrete. In some cases, like with stone or slate siding, the contractor will have to work from inside your home to add insulation. In this case, they’ll drill through your drywall, and you’ll have to touch up the paint later.

3. The Insulation Installers Will Use a Hose to Fill the Cavities

Next, the installers use special equipment to run the injection foam insulation material through a hose and directly into the wall cavities through the holes they’ve just drilled. Injection foam insulation can be installed in walls with existing fiberglass and cellulose insulation, so there’s no removal process for the existing insulation. (Note: If the wall cavity has glued-in cellulose, you may not be able to install injection foam.)

4. The Crew Cleans As They Go

While one pro is injecting the foam insulation, another crew member will clean up any messes before it hardens. A third crew member will clean up any drips or wood shavings that fall to the ground.

5. The Team Will Plug Up the Holes

After every cavity is filled completely, the team will begin replugging the holes:

• For aluminum and vinyl siding, they’ll use styrofoam plugs and reinstall the strip of siding back over top.

• For wood siding, they’ll use wood plugs and stain them to match the rest of the house.

• For brick and concrete, they’ll re-mortar the holes they drilled.

The whole process will take between 3 and 5 hours, depending on the size of your house and the size of the installation team. The foam will harden over the next 24 hours.

Injection Foam Insulation Costs

It’s clear that injection foam has lots of benefits, and it’s also best left to professionals for installation. That begs the question: How much does injection foam insulation cost?

Installing injection foam insulation in a home costs between $4,000 and $9,675, but these costs can vary dramatically depending on a number of factors—primarily the size of your house. The more stories and exterior wall square footage your home has, the higher your costs will be. Location, time of year, and your home’s accessibility can also impact the cost.

That’s significantly more expensive than cellulose or fiberglass insulation costs and even more than the cost of blown-in insulation. It’s more comparable to the cost of spray foam insulation, though still higher. But for many homeowners, it’s well worth the investment. The installation is a lot less disruptive to your home, and the insulation material is one of the most effective in the industry. That means lower energy bills, more soundproofing, better fireproofing, and no insulation settling over time.

DIY Perspectives

While it’s possible to install some types of insulation yourself, injection foam insulation should absolutely be left to a local insulation professional. The work is complex and requires expensive equipment, and the insulation material can contain toxic emissions. Pros will have the proper safety gear to keep them safe during installation.

Is Injection Foam Right for Your Home?

Wondering if injection foam insulation makes sense for your home? Here are a few reasons you might want to consider this insulative material:

• You have fiberglass or cellulose insulation, but it’s old and not as effective as you’d like—and it shows in high energy bills.

• Your home is prone to fluctuating temperatures and uncomfortable drafts.

• You don’t want to have to make a mess inside your home to install new insulation.

• You want an effective insulation that also doubles as fireproofing and soundproofing and isn’t conducive to mold, mildew, and condensation.

• You plan to live in this house for a while, so you don’t mind spending more on a quality insulation material.