I've been reading a lot of info from Europe on rock wool. It is claimed to be close in R-value to foam and much greener with open vapor. I am interested in using for exterior and basement insulation. Does anyone have experience using rigid rock wool? Thanks.
Rock wool is available in rigid product, with various densities, depending on application.
There is a product designed as drain board for foundations.
It's available in pipe insulation, batts, and blown in. Although you may have a hard time finding or getting.
Look for industrial / commercial / wholesale insulation suppliers.
It's fireproof & waterproof, lower embodied energy than foam, but has formaldahyde glues still.
I have used a few brands of rigid batts for air sealing and found the Roxul brand better. Roxul is more dense and easier to cut and we use it frequently for air sealing in areas where foam will not work and some chase areas. Most brands are marketed as acoustical batting, however I have seen Roxul reps at the big box stores promoting the product for general attic/wall insulation against fiberglass. For attics cellulose is more cost effective and any rigid batt (rock wool or fiberglass) used in attic insulation is problematic. Rock wool has great thermal characteristics and does not wick water making it a good choice for basements and exterior applications. My only complaint is rock wool (slag) fibers are nasty.
For exterior application do you attach directly or with drainage plane?
I have not used Roxul for exterior applications- only airsealing and basements. Check their website as I believe Roxul offers additional products specifically for exterior applications