What type of insulation provides the best soundproofing?

The best choice for soundproofing insulation is rock wool insulation. Rock wool, also known as mineral wool, is composed of natural rock and minerals. Its dense and fibrous structure effectively dampens sound waves, making it an excellent choice for reducing noise transmission between rooms or from outside. Unlike fiberglass, which is less dense and can be more effective for thermal insulation, rock wool's superior sound-absorbing properties stem from its ability to trap sound waves within its composition.

In addition to soundproofing, rock wool insulation also has fire-resistant properties, which makes it doubly beneficial in construction. It has a higher density compared to fiberglass batts, which contributes to its effectiveness in controlling sound transmission. While cellulose insulation and spray foam insulation have their benefits, they do not offer the same level of sound dampening as rock wool insulation.