It seems like historically people underestimated the insulation value of polyurethane because apparently it doesn't necessarily do well on the conventional R-va

It seems like historically people underestimated the insulation value of polyurethane because apparently it doesn't necessarily do well on the conventional R-value score. Apparently a solid inch of sprayed polyurethane can provide 90% insulation, and 2 inches gets you to 99% insulation. https://www.monolithic.org/blogs/presidents-sphere/r-value-fairy-tale-the-myth-of-insulation-values https://www.monolithic.org/blogs/presidents-sphere/r-value-f...