Very similar to fiberglass, rock wool or mineral wool is made from slag, the remains of the steel making process.
- Handles heat very well.
- Used as a fire-stop in commercial buildings.
- Good sound absorption, the best by a small margin.
- High recycled content.
- Somewhat hard to find.
- Rare in blowing wool form.
- Does not prevent radiant heat transfer – the primary source of heat-flow in and out of buildings.