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Polystyrene Insulation vs. Polyurethane

Do you want your Minneapolis or St. Paul area home to be more comfortable and less expensive to heat and cool? If so, you might be interested in the benefits of foam insulation. You have two main types to choose from: rigid foam (polystyrene) and spray foam (polyurethane).

These two insulation materials sound similar but they have their differences! Learn more about your options to help you make the best choice.

Polystyrene Rigid Foam Insulation

Rigid foam is primarily installed in unfinished walls, roofs and foundations. The dense product provides a higher R-value than other types of insulation, allowing for excellent performance with very little thickness. Installing rigid foam reduces thermal bridging, raises the R-value of a wall or roof assembly, and greatly reduces air leaks.

There are two types of polystyrene rigid foam insulation:

  • Expanded polystyrene (EPS): With an R-value of 3.6 to 4.2 per inch, EPS is an effective way to insulate a home. It’s the less expensive option of the two and is most appropriate for above-grade applications.
  • Extruded polystyrene (XPS): An impressive rating of R-5 per inch combined with high compressive strength and water resistance makes XPS the perfect insulation for below-grade slabs and foundation walls.

Polyurethane Spray Foam Insulation

Spray foam is the best type of insulation for reducing air leaks. It foams in place, allowing you to fill every nook and cranny. This makes spray foam ideal for oddly shaped spaces and filling gaps around floor and wall penetrations. However, because spray foam must be mixed on site and applied while wearing special protective clothing, you must leave installation to the professionals.

There are two types of polyurethane spray foam insulation:

  • Open-cell polyurethane foam: Expect an R-rating of about 3.6 per inch. Open-cell foam is permeable to moisture but impermeable to air. This makes it ideal for insulating roof assemblies that need to dry inward.
  • Closed-cell polyurethane foam: At about R-6.5 per inch, closed-cell foam offers the best R-value per thickness of any insulation. It has a glue-like consistency, adding structural integrity to any wall or ceiling you apply it to. This option is pricier than open-cell foam, but because it provides better R-value per inch and also acts as a vapor retarder, it may be the better option for your situation.

Install Foam Insulation in Minneapolis-St. Paul

Although polystyrene insulation (rigid foam) is often installed during new construction, there are sometimes exceptions for retrofit projects. For help choosing between polystyrene rigid foam and polyurethane spray foam, and then installing the insulation, contact Metro Home Insulation!


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– Sara in Prior Lake, MN
Products We Install

We install blown and batt fiberglass in homes and buildings.


Environmentally friendly and effective, cellulose works well in homes and buildings.

Spray Foam

Our team installs energy-efficient spray foam insulation to keep homes and buildings more comfortable.


Help prevent mold and moisture infiltration in homes you build with our waterproofing services.

Insulation Removal

Metro Home Insulation provides home insulation removal services.

Air Sealing

We include air sealing in our insulation projects to help maximize your energy efficiency.

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