As an insulation contractor, we get asked tons of questions about foam insulation for existing homes, including the foam insulation installation process, cost, safety, and worst-case scenarios.

RetroFoam of Michigan has been installing existing home insulation across the Lower Peninsula since 2002. We are licensed, insured, and don’t subcontract the job out. All of our crews are trained by our foam manufacturers -- because foam insulation is all we do.

Top FAQ About Foam Insulation for Existing Homes

If you're looking to improve energy efficiency and comfort in your home, foam insulation can be a game-changer.

But if your house is already built, you may be wondering whether it's still an option. 

The good news? Foam insulation for existing homes is not only possible, but it can also significantly enhance your home's insulation without the need for major renovations.

Here we'll answer some of the most frequently asked questions about injection foam and spray foam insulation, their benefits, cost, and how it compares to other insulation options.

What’s the difference between RetroFoam injection foam and spray foam insulation?

The key difference between RetroFoam injection foam and spray foam insulation lies in their application methods, rather than their efficiency.

Spray foam insulation is typically used in new construction homes, as well as open cavities in existing homes such as attics, crawl spaces, and rim joists. It expands upon application, creating an airtight seal in open areas.

RetroFoam injection foam, on the other hand, is designed specifically for existing homes. It is injected into enclosed walls through small drilled holes, allowing homeowners to improve their insulation without major renovations.

READ MORE: Injection Foam Insulation vs Spray Foam Insulation: What's the Difference?

How much money does spray foam insulation save on monthly energy bills?

Our customers have reported energy savings ranging from 15 to 50 percent on their monthly bills.

The exact amount saved depends on several factors, including the age and construction of the home, thermostat settings, and individual lifestyle habits.

READ MORE: 5 Common Comfort and Energy Bill Savings According to RetroFoam of Michigan Reviews

How does the cost of spray foam insulation compare to fiberglass and cellulose?

Foam insulation typically costs two to three times more than blown-in cellulose or fiberglass.

However, while the initial investment is higher, foam insulation provides a superior air seal that helps reduce energy costs over time, leading to significant savings on monthly utility bills.

READ MORE: The Total Lifetime Cost of Foam Insulation: It’s Less Than You Think

What financing options are available for existing home insulation?

Homeowners have several financing options to make their insulation projects more affordable.

Michigan Saves provides low-interest loans specifically for energy-efficient home improvements, helping you upgrade your insulation with manageable payments.

Additionally, we partner with GreenSky to offer flexible financing solutions, making it easier to invest in energy savings for your home.

Does old insulation need to be removed before installing foam insulation?

Whether old insulation needs to be removed depends on the area of your home being insulated.

• Attics, crawl spaces, and rim joists -- Existing insulation must be removed to allow spray foam to properly adhere and create an effective air seal.
• Exterior walls -- In most cases, old insulation can remain in place. Injection foam compresses the existing material as it fills the cavity, ensuring complete coverage without requiring removal.

READ MORE: Do I Need to Remove Old Insulation Before Installing New?

Which type of spray foam insulation is best for your home: Open cell or closed cell?

For most homes, open cell spray foam is the preferred choice over closed cell insulation.

Both types create an effective air seal, but open cell offers additional benefits including sound dampening, flexibility, and the ability to identify leaks more easily. It is also a softer, more pliable material that works well in residential applications.

Closed cell spray foam, on the other hand, is denser, more rigid, and higher in cost. It conceals leaks and provides additional structural reinforcement, making it a better choice for pole barns, commercial buildings, and areas requiring extra durability.

READ MORE: Open Cell vs Closed Cell Foam Insulation: Which is Better for My Home?

Can injection foam cause drywall to crack or pop off during installation?

Although uncommon, injection foam can sometimes cause slight bowing or cracking drywall.

The good news is that reputable contractors will repair any damage at no cost to the homeowner. At RetroFoam of Michigan, we stand by our work with a lifetime warranty, ensuring homeowners are fully covered for any potential issues.

How long does it take to install spray foam insulation in an existing house?

In most cases, spray foam insulation can be installed in a single day.

However, larger projects or those requiring the removal of old insulation -- such as in attics -- may take up to two days to complete.

What factors affect the cost of foam insulation in an existing home?

The primary factor influencing the cost of foam insulation is the size of the area being insulated.

Additional factors include the type of insulation material used, the required application thickness, and the type of siding on your home, all of which can impact pricing.

READ MORE: How Much Does Foam Insulation Cost for an Existing Home?

How much is your minimum charge?

Like other contractors, foam insulation companies have a minimum charge, which can vary based on several factors.

At RetroFoam of Michigan, our minimum charge is $2,000, depending on the project scope and the type of foam insulation used. This is important to consider if you're planning to insulate a small area.

How do you ensure a wall cavity is completely filled with foam insulation?

The foreman carefully inserts the injection hose from the top to the bottom of the exterior wall cavity to ensure even coverage.

If any obstructions or blockages are encountered, an additional hole is drilled above or below the obstruction, allowing more foam to be injected and ensuring the cavity is completely filled.

Is foam insulation safe and free of harmful chemicals?

Yes. Both injection foam and spray foam insulation are safe for use throughout your home.

The spray foam insulation we use is Gold Green certified and has low VOCs, ensuring minimal impact on indoor air quality. RetroFoam injection foam is completely non-toxic and produces no off-gassing, making it a safe and eco-friendly insulation choice.

How does siding affect the installation of injection foam insulation?

The process of installing injection foam insulation varies depending on the type of exterior siding your home has.

Most homes feature aluminum, vinyl, wood, or brick siding, and each requires a unique approach.

• Aluminum or Vinyl Siding -- A section of siding is carefully removed, and holes are drilled into each stud cavity. The foam is then injected, the holes are plugged, and the siding is reattached seamlessly.
• Brick Exteriors -- Small holes are drilled into the mortar joints at the top, middle, and bottom of each stud to inject the foam. Once the insulation process is complete, the holes are filled with mortar to match the existing points.
• Wood Siding -- If the siding can be removed, the process is similar to aluminum or vinyl siding. If removal isn't possible, holes are drilled directly into the wood siding, foam is injected, and the holes are sealed with wood plugs to maintain the home's appearance.

READ MORE: Installing RetroFoam into Exterior Walls with Different Siding Types

Can injection foam insulation be installed from the inside?

Yes, injection foam insulation can be installed from the inside of your home, though it requires additional preparation due to its more intrusive nature.

Before installation, the area must be cleared, with furniture moved at least six feet away from the walls, and floors and surfaces covered for protection.

Small holes are then drilled into the drywall at each stud cavity, allowing the foam to be injected. Once the cavities are fully insulated, the holes are sealed with plugs, and a rough coat of drywall mud is applied to prepare for final finishing.

Will plaster or paneling affect injection foam installation?

Can injection foam cause bowed paneling or cracked plaster?

While it's possible, it's not common with proper installation.

Plaster walls trend to be stronger than drywall, making them less likely to crack during the process. Paneling, on the other hand, requires a more delicate approach due to its flexibility. A skilled insulation contractor will carefully control the pressure inside the wall cavity to prevent damage, ensuring a smooth and safe installation.

What rebates are available for home insulation?

Homeowners in Michigan may qualify for energy-efficiency rebates from providers like Consumers Energy, DTE, and SEMCO, among others.

Rebates can range from up to $50 for rim joist insulation, $250 for attic insulation, and up to $1,000 for whole-home insulation.

During your consultation, your project manager will review available rebates and help determine which ones you may qualify for, maximizing your savings.

READ MORE: Finding Insulation Rebates to Lower the Cost of Home Insulation

How does foam insulation help with sound reduction?

The thick, soft structure of open cell foam absorbs sound waves, helping to reduce outside noise and create a quieter indoor environment.

While foam insulation effectively dampens sound, it does not provide complete soundproofing.

READ MORE: Soundproofing vs Sound Dampening a Room: What's the Difference?

How do you insulate a cathedral ceiling with no attic access?

There are a few methods for insulating cathedral ceilings in existing homes.

• Roof Injection -- Some contractors install the foam by drilling through the roof. This process requires coordination with a roofing contractor to ensure proper sealing and roof integrity.
• Ceiling Cut Method -- The most effective and our preferred approach involves cutting strips into the ceiling and spraying foam into each cavity. After insulation is applied, the drywall is replaced, and a rough patch of mud is applied over the seams. The homeowner will need to complete the final finishing and painting.

Learning More About Spray Foam Insulation for Existing Homes

If you would like to continue your educational journey in regards to foam insulation for existing homes, head on over to the Learning Center on our website.

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