What is Part E and when does it apply?

Part E of the UK Building Regulations covers resistance to the passage of sound. It applies to separating floors between flats and dwellings formed by conversion. New-build flats must achieve minimum airborne sound insulation of 43 dB DnT,w and impact sound insulation of 64 dB LnT,w. Acoustic underlay and decoupling mats help meet these requirements.

Do I need acoustic underlay for laminate flooring?

Yes, acoustic underlay is strongly recommended for all laminate and engineered wood flooring. It reduces impact noise transmitted to rooms below, improves the feel underfoot, and most laminate warranties require an underlay. For flats with separating floors, acoustic-rated underlay is a Building Regulations requirement.

What is a decoupling mat?

A decoupling mat (also called an acoustic mat or isolation membrane) sits between the subfloor and the flooring to break the direct transmission path for sound. It absorbs impact energy before it reaches the structure. For tiled floors in flats, a decoupling mat is essential for Part E compliance and also prevents grout cracking from substrate movement.

What thickness acoustic underlay do I need?

For laminate/engineered wood: 3-5mm foam or rubber crumb underlay. For vinyl/LVT: 1.5-2mm self-adhesive acoustic underlay. For tiles: 5-6mm decoupling mat. For carpet: 8-11mm impact-rated underlay. Thicker is not always better — check the flooring manufacturer's maximum underlay thickness recommendation.

Do I need a resilient perimeter strip?

Yes, for Part E compliance. A resilient perimeter strip (usually 5-10mm thick closed-cell foam) is fitted around the room edges between the floating floor and the walls. It prevents flanking sound transmission — sound bypassing the floor through the walls. Skirting boards then cover the strip.

TradeCalculator

Acoustic Flooring Calculator — Underlay, Mat & Adhesive

Calculate acoustic underlay, decoupling mat and adhesive quantities for sound-rated flooring. Covers Part E compliance for flats.

Room Area

Floor area of the room

Floor Type

Type of flooring being installed

Building Regs Requirement

Part E applies to separating floors in flats

How We Calculate This

This calculator works out acoustic flooring material quantities based on your room area, floor type and Building Regulations requirement.

What we calculate

Underlay: Roll count based on room area plus overlap allowance
Adhesive: For vinyl/LVT and tile installations (kg per m²)
Acoustic mat: For Part E and BREEAM compliance — added as a separate layer
Perimeter strip: Resilient foam strip around room edges
Joining tape: Foil tape for sealing underlay sheet joints

Overlap allowance

Underlay sheets must overlap at the joints to prevent sound leakage. The default is 100mm overlap, which adds approximately 10% to the total underlay area. Some manufacturers specify different overlap requirements — check their installation guides.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.