How are Clopay Intellicore garage door R-values so high

garage-doorinsulationpolyurethane

Clopay's garage doors with their proprietary "Intellicore" polyurethane foam insulation claim R-values as high as 20.4 in a 2" thick door, or R-10.2 per inch.

State-of-the-art spray polyurethane insulation has an initial R-value up to 6.7 per inch, or about 65% of what Clopay claims (in a best-case scenario).

Clopay's technology is proprietary, but how is such a high R-value even technically possible for a polyurethane foam?

EDIT 1:

I realize that there are other elements besides foam in the door, but their cross section illustration (top of page) depicts polyurethane foam injected into a steel shell. The steel certainly does not increase the R-value, so the R-value apparently comes solely from the foam.

EDIT 2:

Some context for posterity: I'm considering building my own insulated garage door, and through some research I found that Clopay appears to lead the market in garage door R-values. Trying to see if (and how) I can get anywhere close to their R-values.

Best Answer

Note the fine print in the chart: "Calculated door R-Value is in accordance with DSAMA TDS-163". Here is DSAMA TDS-163.

From the PDF:

Refer to Figure 1. A typical insulated door has an exterior surface, interior surface, and an insulating core material. Also present is the insulating effect of air on a vertical surface, termed “air film”. Each of these elements has a unique R-value that added together create the door section R-Value. Rsection = Rair films + Routside surface + Rinsulation +Rinside surface

So the 20.4 value includes not only the 2" of foam, but the R values from the outside surface, inside surface, and some air films that are assumed not to be moving. I expect you're correct that the foam alone would provide a value more in line with the typical 6-7 R/inch you're used to.

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