Underfloor Insulation & Soundproofing — Lifted Floor, Insulation Between Joists, New Acoustic Deck

The customer needed the existing finished floor lifted so that proper insulation could be installed between the joists — to reduce heat loss into the cold void below and improve airborne and impact noise transmission from the room below.

On-site assessment of the existing suspended-timber floor and the void beneath, followed by a four-stage underfloor build-up: lift existing floor → install mineral wool insulation between joists → fix resilient acoustic bars across the joists → lay new moisture-resistant acoustic boards (RW5 system) as the new deck.

The existing floor build-up offered virtually no thermal or acoustic insulation: heat was being lost downward into the void, and sound was transmitting directly through the joists as both airborne and impact noise. The joists themselves were sound and reusable, so the optimal solution was an insulated, decoupled new deck rather than a full replacement.

Lifted the existing floor and exposed the joists; installed mineral wool insulation between the joists (thermal + acoustic); fixed resilient acoustic bars across the joists to decouple the new deck from the structure; finished with moisture-resistant acoustic boards (RW5 system) ready for the floor finish. Every stage was photographed for the client's records.

A warmer, measurably quieter room with a clean, fully-documented build-up. The client confirmed they would happily reuse RetrofitIQ for similar works or general construction — verified in his Checkatrade review.