Wave Dynamics GuidesTGD E Explained: Sound Insulation in Irish Buildings
A plain-English guide to Technical Guidance Document E (2014): what it covers, the airborne and impact criteria, common areas and how compliance is shown.
In Short
TGD E is the Technical Guidance Document that shows how to meet Part E (Sound) of the Irish Building Regulations. It sets the sound insulation performance expected between dwellings, at least 53 dB DnT,w for airborne sound and no more than 58 dB L′nT,w for impact sound through floors, and covers reverberation in common areas.
- Part E has two requirements: E1 sound insulation between dwellings, and E2 reverberation in common internal areas.
- Separating walls and floors: DnT,w of 53 dB or more. Separating floors: L′nT,w of 58 dB or less.
- Applies to new dwellings and dwellings created by a material change of use.
- Compliance is shown through good design and detailing, confirmed by pre-completion testing.
What Is TGD E?
Part E of the Second Schedule to the Building Regulations sets the legal requirement: dwellings must be designed and built to give reasonable resistance to sound from neighbouring dwellings, and common internal parts must limit reverberation. Technical Guidance Document E (2014) is the official guidance on how to meet that requirement. Following it is the usual way to show compliance, although other approaches can be used if they achieve the same result.
Requirement E1: Sound Insulation Between Dwellings
E1 covers walls and floors that separate one dwelling from another, and from other spaces such as corridors, stairwells, plant rooms and commercial units in the same building. TGD E sets the following minimum on-site performance:
| Element | Airborne (DnT,w) | Impact (L′nT,w) |
|---|---|---|
| Separating walls | 53 dB or more | Not applicable |
| Separating floors | 53 dB or more | 58 dB or less |
These are mean values for a set of tests on each construction type. The guidance also gives example constructions and junction details that, if built well, are expected to achieve these values.
Requirement E2: Reverberation in Common Areas
E2 deals with echo and reverberation in shared internal circulation areas such as entrance halls, corridors and stairwells serving flats. Hard, reflective surfaces build up noise that carries to apartment doors. TGD E sets out how much sound-absorbing finish is needed, typically through an absorptive ceiling, and gives a calculation method to check the amount provided.
How Compliance Is Shown
Good acoustic design starts at planning or early design stage, when wall types, floor build-ups and junctions are chosen. TGD E then asks for pre-completion sound insulation testing on a sample of each separating construction, carried out by a competent tester. The results go into the completion documentation for Building Control. Our guide to sound insulation testing explains what happens on the day.
Flanking: Why Junctions Matter
Sound does not only travel straight through a separating wall or floor. It also travels around it through connected walls, floors, ceilings and façades. This is called flanking transmission, and it is the most common reason a good wall still fails on site. TGD E gives junction details for exactly this reason, and they should be followed closely on drawings and on site.
Frequently Asked Questions
Does TGD E apply to commercial buildings?
TGD E applies to dwellings. Where a dwelling shares a wall or floor with a commercial unit or other non-domestic space, that separating element must still meet the TGD E criteria.
Is TGD E the same as Approved Document E?
No. Approved Document E applies in England and Wales and uses different ratings (DnT,w + Ctr) and criteria. See our guide to Approved Document E vs TGD E.
Does TGD E cover noise from outside, such as roads?
No. External noise intrusion is dealt with through planning conditions and guidance such as ProPG and BS 8233, not Part E.
This guide gives general information and is not a substitute for project-specific advice. Requirements change, so always check the current regulations, guidance and your planning conditions. Ask our team about your project.
Jon Maguire (BSc Hons MIOA) brings over 8 years of expertise in acoustic consultancy, specialising in environmental acoustics with a focus on 3D modelling, assessments, and detailed design for industrial, commercial, and energy projects. He has lead noise assessments for key clients while thriving in multidisciplinary environments. Jon’s diplomatic communication skills are ideal for stakeholder consultation.
Jack is a Field Engineer at Wave Dynamics, supporting the delivery of environmental monitoring and acoustic consultancy services through detailed on-site fieldwork. He has hands-on experience in noise monitoring, vibration monitoring, and dust monitoring across a variety of infrastructure, construction, and environmental projects. Jack is involved in the setup, operation, and maintenance of monitoring equipment, ensuring accurate data collection in line with relevant standards and project requirements. He works closely with consultants and project teams, providing reliable field support that underpins high-quality assessments and reporting.
Aidan is the Director for all U.K Operations and has worked in multiple industries including for clients in the UK and internationally operating in the residential, industry, healthcare, education, and construction sectors.
