Acoustic quilt and impact sound in a loft room
A converted loft used as a bedroom or study is normally expected to meet a level of impact sound insulation to the ceiling below, which is usually achieved through a combination of mineral wool or acoustic quilt between the joists and an acoustic-rated underlay under the finished floor.
Neither layer alone tends to give the same result as the two working together, so flooring underlay should be treated as part of the acoustic package rather than a separate, optional extra chosen purely for comfort underfoot.
- Acoustic underlay under carpet or LVT works alongside quilt between joists, not instead of it
- Skipping the underlay upgrade to save build-up height can undermine the sound insulation the conversion was designed to achieve



