Sound and vibration control

Plant on a roof, a gym above an office, a dance floor over a restaurant, a lift beside a bedroom: in each case energy enters the structure and re-radiates somewhere else as noise. Adding mass to a partition does nothing about it, because the sound never used the partition. The path has to be broken where the energy enters.

• Vibration isolation — machines and plant set on isolators chosen for their running speed.
• Floating floors — a floor built clear of the structural slab.
• Dance floors — sprung and isolated floors for clubs, studios and halls.

1. Identify the source and how it is coupled to the structure.
2. Measure what arrives in the receiving space, and when.
3. Select isolation for the frequencies that actually matter.
4. Detail every rigid bridge out — pipes, conduits, skirtings, thresholds.
5. Inspect before the finishes close the work in.
6. Measure again once complete.

Rarely because the isolator was wrong; nearly always because something rigid was left connecting the two structures. A screed touching a wall, a pipe cast through a floating slab, a skirting screwed to both sides, a duct strapped hard to the soffit. One bridge can undo an entire floated build, which is why the inspection before the finishes go down is part of the work rather than an extra.

One rigid connection undoes an entire floating build. Most failures are a bridge, not a specification.