“Penny wise and pound foolish.” Robert Burton coined the phrase in 1621 to describe people who submit to the allure of upfront savings at the risk of incurring more significant expenses down the road.

To be sure, cheaper is sometimes better – but rarely when it comes to insulation. You want the insulation at your home, place of work, or agricultural building to excel at its job for many years to come. You also want it to safeguard your property against water infiltration. In this case, being pound-wise means investing in spray foam insulation.

Rigid Foam Insulation: Cheap With Many Shortcomings

Rigid foam insulation (RFI) is the primary alternative to spray foam. It is available as expanded polystyrene (EPS), extruded polystyrene (XPS), or polyisocyanurate (polyiso). Still, regardless of its composition, RFI is installed as solid sheets. 

Different types of RFI have varying R-values. Newly installed EPS’ R-value is usually 3.8 per inch, and XPS is 5 per inch, but polyiso leads the pack at 6.8 per inch. Sheets of RFI are typically available in thicknesses ranging between 0.5 and 2 inches, allowing you to install thicker sheets when you desire more excellent insulation. 

In addition to its versatility, RFI is also easy to remove – a great benefit when you wish to avoid making permanent changes to a historic structure. Better yet, RFI rarely costs more than $0.75 per square foot. EPS, the least expensive form of RFI, may cost as little as $0.25 per square foot.

While inexpensive and unarguably effective, RFI comes with many drawbacks. First of all, it takes more effort, so more time. Any gaps could permit air infiltration. Sheets and boards are methodically taped for the same reason. RFI will degrade in response to sun exposure to ultraviolet (UV) light and must be protected accordingly. Air bubbles within RFI can retain moisture which compromises its insulation properties, often necessitating an additional moisture barrier. RFI is typically too brittle for underground installation. Perhaps worst of all, RFI’s R-value significantly diminishes over time.

Open Cell Spray Foam: More Expensive Than RFI, but Worth It

Open-cell spray foam (OSSF) is the more affordable form of spray foam insulation, typically costing between $1 and $1.25 per square foot. Its R-value, which ranges between 3.6 and 3.9, is lower than that of some types of RFI, although its benefits significantly compensate for its relatively lower insulation properties.

Chief among OSSF’s benefits is its easy installation. OSSF expands immediately following air exposure, enabling it to quickly fill any nooks and crannies it is installed around. OSSF also forms an excellent barrier against sound, making it a natural choice for homes or businesses located near busy roads. And like the more affordable spray foam option, it is an attractive option for property owners adhering to a strict budget.

But compared to the superior (and costlier) type of spray foam, OSSF has one significant shortcoming: Just like RFI, it is permeable to water. This means an extra vapor barrier must be installed over OSSF, or its R-value will decline due to water retention.

Closed Cell Spray Foam: Most Expensive, but the Best of All Worlds

At approximately 6.5, closed-cell spray foam (CCSF) boats an exceptional R-value. When it comes to retaining heat and reducing energy costs, CCSF is the king of spray foam insulations. But with its cost of $2 to $3 per square foot, CCSF also represents the greatest upfront investment. Is it worth it?

Beyond a doubt, yes. CCSF’s outstanding R-value makes it the ideal choice for insulating areas of a building that have very limited space. It packs nearly twice as much insulation into the same space that OSSF could. And like OSSF, CCSF is far easier to install on vertical surfaces than RFI. 

Unlike the alternatives, CCSF is not water permeable. It cannot trap water vapor, so it retains its R-value over time while simultaneously creating a barrier that safeguards the structure against water infiltration. And unlike spongy OSSF, CCSF is rigid and exceedingly strong. It literally acts like a glue that holds a structure together and will fortify any surface it coats. This is why CCSF is the preferred choice in areas that are frequently racked by powerful storms, the Midwest included.

In summary, closed-cell spray foam offers more than enough value to justify its greater upfront cost!

The NIJAC team specializes in spray foam insulation. Our industry-leading spray foam products and installation techniques make our team the one to count on. We’ve got you covered when you want to insulate a residential, commercial, or agricultural property anywhere in the Midwest or nationwide. To learn more about how we can create outstanding and long-lasting value by insulating your property, we welcome you to contact us today!