Rockwool from international (China) suppliers It seems that a simple internet search turns up hundreds of sources of rockwool from China. This seems like a product which is dominated by a few (1?) suppliers here in North America. With some sleuthing, it seems like something that could be had for a lot less money per inch... I understand the possible downsides of unknown suppliers, but this seems like a widely used product outside of the NA market. I also remember horror stories about Chinese drywall and laminate flooring. I am only considering this for subslab and exterior foundation insulation. I don't like getting everything from China, but I also don't like how just a few suppliers/brands are able to dominate certain markets. The rockwool industry in China sort of resembles the EPS market here in NA. I will be getting a free sample from a few manufacturers and see i fit looks like Roxul.

Look at the density too, not just the thickness (and get thermal performance specs too, if you can). Mid to high density rock wool is usually more than R4/inch from N. American manufacturers, but it's possible to buy low density stuff that's in the ~R3/inch range (or lower) in other parts of the world. Most rigid rock wool will be of sufficiently high density, but try to figure that out.

There's nothing inherently wrong with building materials sourced in China- many of the large multi-nationals with rock wool products such as ISOVER (Saint-Gobain) have manufacturing capacity there. (It only makes sense, in a country with an extremely large amount of new construction.) The quality of the smaller competition may vary, but it's a competitive market.