Foam Insulation and R-Value — A False Measurement

When asked to insulate commercial buildings, we often recommend SPF (spray polyurethane foam) insulation. R-value, the commercial rating for insulation, isn’t the reason.

R-value is an out-of-date calculation originally meant to rate the efficiency of insulation products and was adopted by the Federal Trade Commission (FTC) to protect consumers against false sales claims.

Foam Insulation — R-value Is Out of Date

Even though SPF has the highest R-value per inch, it gets an inaccurate rating.

R-value is based almost entirely on the thickness of the wall filled with spun fiberglass batt insulation, measured in inches. Thicker insulation material always receives a more favorable final R-value rating, no matter how efficient the material itself actually is.

The problem is that the core concept behind this rating hasn’t evolved with major technological advances in the industry.

So, that means any comparison between fundamentally different types of insulation, such as fiberglass batt insulation and SPF, is like comparing apples and oranges.

Industry practices have been completely changed by more modern methods and materials like polyurethane coating and spray foam insulation.

But, R-value remains important in the minds of customers, as well as those who write commercial building codes.

Once we move away from spun fiberglass as the base material, R-value becomes a meaningless number.

Besides, being able to keep the layer of insulating material thin makes SPF more versatile.

Foam Insulation and R-Value — The Importance of Air Leaks

R-value is calculated in ideal laboratory settings and fails to take into account one of the main advantages of SPF insulation — its airtight seal.

You might think your commercial building is pretty efficient when it comes to heating and cooling, but consider that air moves just like water.

If we filled your building full of water and turned it upside down, would it leak?

It would if you’re using traditional insulation — an indication that you’re losing money on your utility costs to heat and cool your building. Air you have paid to heat or cool is constantly escaping.

A 20-mph wind drastically reduces the effectiveness of batt-insulated walls.

Walls filled with professionally applied, closed-cell SPF insulation are sealed nearly airtight, cutting down on wasted energy.

If used on the outside of the building, the water-repellent wrapping is not required. The SPF insulation cannot be left exposed, so it must be covered with a 1/2” drywall or an approved 15-minute thermal barrier.

Foam Insulation and R-Value — Don’t Forget Humidity

Dampness leaves fiberglass batting still less effective against weather. Don’t forget that wherever there is airflow, humidity also seeps through.

(You can read more about weatherization of your commercial building here.)

It’s not a question of thickness, but effectiveness.

Compare a cotton ball with a styrofoam cup.

It’s easy to see which of those choices would be more effective at keeping out wind and moisture, and that means that, when comparing fiberglass batting to a superior material like foam insulation, R-value is pointless.

Spray foam insulation, R-value aside, is simply superior for these everyday, practical reasons that are not accounted for in perfect laboratory conditions.

SPF is used in cold storage warehouses, freezer cases at your local grocery store, food processing plants, and ice cream plants — all of the refrigerated trailers on our highways are filled with closed cell polyurethane foam.

Learn more about SPF insulation here.

Additional Advantages of SPF Insulation

There are even more reasons to choose spray polyurethane foam insulation, R-value aside.

Consider these characteristics:

  • Durability — When applied professionally, there is no sagging
  • Toughness — It has been used on all NASA space shuttles because of its ability to adhere to the surface up to 210 degrees, and it’s the only insulation that can get wet and still insulate
  • Air freshness — Due to the airtight seal, fumes and smells do not permeate inside
  • Comfort — SPF insulated buildings are free of drafts, unlike air passing through seams and then through the batt insulation
  • Cleanliness — Dust, dirt, and allergens stay outside
  • Quiet — SPF has a natural noise-dampening quality that keeps unwanted sound out; it’s ideal for buildings built near highways or in high-traffic areas

Simply put, there are a lot of reasons we recommend spray polyurethane foam, and R-value isn’t one of them.

Foam Insulation and R-value — Actual Savings

There’s actual savings for commercial building owners who are building new air-conditioned offices and warehouses using SPF insulation. The amount of A/C can be reduced by 20%, potentially saving thousands of dollars — we have seen cost savings of up to 40% annually.

In addition, the building will be quieter and more comfortable inside.

So, we can confidently say that our clients’ savings and satisfaction back that conclusion up!

It’s an easy way to be “green” and save your company a lot of money over the life of your building.

Let’s Talk About SPF Insulation for Your Commercial Building

We hope you will not be misled by the out-of-date R-value rating.

Instead, we encourage you to learn more about materials that are fundamentally superior.

Give DFW Urethane a call (or contact us here), and we will be happy to help you with your high-tech green insulation needs.

Instead of choosing foam insulation for R-value, let’s find a solution for your commercial building insulation needs that meets more modern standards.


  1. John Stockton on March 19, 2021 at 3:09 pm

    At the end of the day, engineers still need to be able to calculate heat loss and for that, they need a thermal conductivity value which has traditionally been the R-Value. Which material is superior is not the issue (although SFP is clearly superior), the designers need a value which has typically bee R5/inch.

  2. SPF on November 3, 2023 at 4:03 pm

    Quite a bit of information here. Always looking to learn more. Thanks for the education.

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