What sound insulation do separating walls need?

New-build separating walls between dwellings must achieve a minimum airborne sound insulation of DnT,w + Ctr >= 45 dB when pre-completion tested. For conversions (material change of use), the target is DnT,w + Ctr >= 43 dB. These values are set out in Table 0.1 of Approved Document E (2003 edition incorporating 2015 amendments).

What is the difference between DnT,w and DnT,w + Ctr?

DnT,w is the weighted standardised level difference measuring airborne sound insulation. The Ctr spectrum adaptation term adjusts for low-frequency sounds (bass, traffic noise). DnT,w + Ctr gives a more realistic single-number rating. Part E specifies DnT,w + Ctr as the performance standard because it better represents real-world complaints like bass music and traffic.

When is pre-completion testing required?

Pre-completion testing (PCT) is required for all new-build dwellings with separating walls or floors, unless the builder uses Robust Details (www.robustdetails.com) which are pre-approved constructions that have been demonstrated to meet Part E without on-site testing. PCT must be carried out by a member of a UKAS-accredited body or registered scheme.

Do internal walls and floors within a dwelling need sound insulation?

Part E Section 0 deals only with separating elements between dwellings and between dwellings and common areas. Internal walls and floors within a single dwelling have no statutory acoustic requirement under Part E, though good practice is to use similar specifications particularly between bedrooms and noisy rooms.

Does Part E apply in Scotland and Northern Ireland?

Scotland has its own acoustic requirements under Technical Handbook Section 5 (Noise), with similar but not identical performance standards. Northern Ireland uses Technical Booklet G which broadly aligns with AD-E. Requirements may vary slightly — always check the relevant jurisdiction's documents.

Part E Acoustic Performance Standards

Airborne and impact sound insulation requirements for separating walls and floors, referencing Approved Document E: Resistance to the Passage of Sound (2003 edition incorporating 2004, 2010, 2013, and 2015 amendments).

Minimum Performance Standards (AD-E Table 0.1a & 0.1b)

Element	Test Parameter	New Build	Conversion
Separating wall (airborne)	DnT,w + Ctr	≥ 45 dB	≥ 43 dB
Separating floor (airborne)	DnT,w + Ctr	≥ 43 dB	≥ 43 dB
Separating floor (impact)	L'nT,w	≤ 64 dB	≤ 64 dB
Wall between dwelling and common area (airborne)	DnT,w + Ctr	≥ 43 dB	≥ 43 dB
Floor between dwelling and common area (airborne)	DnT,w + Ctr	≥ 43 dB	≥ 43 dB

Internal Walls and Floors Within a Dwelling (AD-E Section 3)

Element	Requirement
Walls between bedrooms and bathrooms/WCs	Good practice guidance only (no statutory minimum)
Floors between rooms in dwellings formed by conversion	Rw ≥ 40 dB recommended
Walls between rooms and refuse chutes/lifts	See AD-E Section 4 for specific guidance

Pre-Completion Testing (PCT) Requirements

Requirement	Detail
When required	All new-build dwellings unless using Robust Details
Test standard	BS EN ISO 16283 (replaced BS EN ISO 140)
Sample rate (first dwelling type)	1 set of tests per dwelling type per site
If test fails	Remedial work required, then re-test
Tester accreditation	UKAS-accredited or registered with ANC/ATTMA scheme

Related Calculators

Use the Sound Insulation Calculator for estimating acoustic performance. See the Part E Sound Reduction page for wall and floor construction specifications.

Always check the latest edition of Approved Documents on the Planning Portal (planningportal.co.uk) as regulations are updated periodically.