How to Lay Acoustic Underlay — Step by Step

Apr 7, 2026

Written by our acoustic insulation specialist — 15+ years experience supplying soundproofing to UK homeowners, developers and contractors. About our experts.

Installation guide from our acoustic insulation specialist.

Laying acoustic underlay correctly is as important as choosing the right product. Follow this guide to get the full performance from your underlay.

Step-by-Step

  1. Prepare substrate — clean, level, dry
  2. Lay from one wall, leaving 10mm perimeter gap
  3. Butt joins tightly — no gaps, no overlaps
  4. Tape all joins with acoustic tape
  5. Turn up at perimeters by 10mm (acoustic break)
  6. Lay floor finish as floating floor — no rigid fixings through the underlay
  7. Trim perimeter, seal with acoustic sealant, fit skirting

Common Mistakes

  • Gaps at joins — even 5mm gaps significantly reduce performance
  • Not turning up at perimeters — flanking path that undermines the system
  • Rigid fixings through the underlay — creates sound bridges
  • Installing on damp substrate

Using our 6mm acoustic underlay or 3mm option? Contact us for free installation advice.


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