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Answers to the Most Frequently Asked Questions About Foam Insulation for Existing Homes
Amanda Ringler

By: Amanda Ringler on March 14th, 2018

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Answers to the Most Frequently Asked Questions About Foam Insulation for Existing Homes

injection foam insulation  |  spray foam insulation  |  FAQ  |  existing home insulation



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

RetroFoam of Michigan has been insulating existing home 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.

Since we get so many questions, we have compiled a list of the most frequently asked to help homeowners get all the information they need as they consider making their home more comfortable and energy efficient.

RELATED: Clearing Up Misconceptions about Spray Foam Insulation

Top FAQ About Foam Insulation for Existing Homes

How much is your minimum charge?

All foam insulation contractors, like other contractors, will have a minimum charge that can vary depending on a number of variables. Our minimum charge is between $1,200 and $1,600 depending on the project and type of foam insulation used. This is important to keep in mind if you only plan to insulate a small contained area.

What’s the difference between RetroFoam and spray foam?

The difference comes down to the way the two materials are installed, because there is no difference in the efficiency of the products. Spray foam insulation can be used in new build homes or in the attic, crawl space, or rim joist, as well as any open cavity. RetroFoam is an injection foam that can be injected into the walls of an existing home.

How much money can I save on monthly energy bills with foam insulation?

Our customers have said they saved anywhere between 15 to 50 percent on their monthly energy bills depending on certain factors, like the age of the home, construction, thermostat settings, and lifestyle preferences.

How does foam insulation compare in price to blown-in cellulose or fiberglass?

Foam insulation is two to three times more expensive than blown-in cellulose and fiberglass. While foam is more expensive, it pays you back with the air seal it creates which saves you money on monthly energy bills.

What type of financing is available for insulating my home?

There are a few options for financing your insulation project. EnerBank USA offers a 12-month same-as-cash or low monthly payment traditional term loan financing. Michigan Saves also offers a low-interest loan for energy efficient home updates.700x468_BlownInsulation_jpg.png

Does old insulation need to be removed before foam insulation can be installed?

It depends on the area of the home that is being insulated. If you are insulating the attic, crawl space, or rim joist, then the old insulation must be removed for the spray foam to work properly. If you are insulating your exterior walls, in most cases the old insulation can stay where it is, as the injection foam will compress it as it fills the cavity.


Is open cell or closed cell insulation better to use in my home?

In the majority of cases, open cell spray foam is the better option to use in your home compared to closed cell. While both create an air seal, open cell has sound dampening qualities, doesn’t conceal leaks, and is a softer more pliable material. Closed cell will conceal leaks in the home, is more rigid, more expensive, and doesn’t dampen sound. Closed cell is a much better option for pole barns or commercial buildings.

Can the drywall pop off or crack in existing walls during the installation process?

While rare, this can happen. The good news is any good contractor will make repairs at no cost to the homeowner. At RetroFoam of Michigan, we offer a lifetime warranty.

How long does the install take?

Most houses can be insulated in a day or less, but there are instances where it can take two days especially if old insulation is being removed from a large area like the attic.

What factors impact the cost of foam insulation?

The size of the area to be insulated is the number one factor that determines cost. The material used, application thickness, and the type of siding you have on your home are other determining factors.

RELATED: Spray Foam Insulation Cost and Budget Calculator

How do you know when a wall cavity is completely full of foam?

The foreman at the job will run the injection hose all the way to the top of the exterior wall cavity and then all the way to the bottom. If the foreman runs into any obstructions or blockages, another hole will be drilled either above or below it and more foam will be injected to ensure the cavity is completely filled.

Is foam insulation free of toxins and harmful chemicals?

The quick answer is yes, both injection foam and spray foam insulation are safe to have in every area of your home. The spray foam insulation we use is certified Gold Green and has low VOC. RetroFoam injection foam has no off-gassing and is completely non-toxic.RFM_InjectionCloseUp_jpg-300x169.png

How does siding effect how you insulate exterior walls?

Most houses have either aluminum, vinyl, wood, or brick siding. The process for installing injection foam for each of these is different.

For homes that have aluminum or vinyl siding, a piece is removed from the side of the home and a hole is drilled into each cavity. Foam is injected into the holes, the hole is plugged, and the siding is replaced.

For brick exterior, small holes are drilled through the mortar joints between every stud to inject the foam insulation. When the cavities are full, the holes are re-mortared and matched closely to the existing mortar.

Wood siding is handled differently, if the siding can be removed, it is handled similarly to aluminum or vinyl siding. If it can’t be removed, holes must be drilled through the wood siding, the foam is injected into the cavities, and the holes are filled with wood plugs.

What rebates are available for insulating my home?

There are rebates available to residential customers who make energy efficient home improvements from Consumers Energy, DTE, and SEMCO, as well as a few other companies across Michigan. Rebates could be up to $50 for insulating a rim joist, $250 for an attic, or up to $1,000 for insulating the entire house. During your estimate, your estimator will discuss what insulation rebates you may qualify for.

How does foam insulation work for sound deadening?

The thicker, softer material of open cell foam reduces sound waves keeping outdoor noise out where it belongs. The foam insulation will deaden the sound but won’t sound proof it.

RELATED: 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 ways to insulate cathedral ceilings in existing homes. In some cases, you can drill through the roof to inject foam insulation. In this case the work would need to be coordinated with a roofing contractor.

The most effective option is to cut strips into the ceiling and spray foam into each cavity. The ceiling drywall is then replaced and a rough patch of mud is spread on the seams. The homeowner will need to finish it off and paint.

Learning More About Foam Insulation in 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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Spray Foam Insulation for New Build Homes: Answers to Frequently Asked Questions

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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 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.