ROCKWOOL Multirock is a light-weight water repellent slab for partition walls , ceilings and pitched roofs. Multirock is generally used for excellent  thermal insula­tion and acoustics purposes  in partition walls , attics and pitched roofs where it can be installed as an additional layer below rafters on the in­ner side of the room. Like all Like all ROCKWOOL products it protects against fire; provides acoustic comfort due to its fibrous structure; is uniquely durable against all forms of weather and is only sourced from sustainable materials.