Do I Need Planning Permission for External Wall Insulation?

External Wall Insulation (EWI) is one of the most effective ways to improve the energy performance of existing homes and housing portfolios. It can significantly reduce heat loss, improve comfort, and help properties move towards EPC C and beyond.

One of the most common questions landlords, housing providers, and property owners ask is: “Do I need planning permission before installing external wall insulation?” 

The answer is:

sometimes...

...depending on the building type, location, and the extent of the works.

While we are not planning consultants, Target Green works on retrofit projects across the UK and regularly supports clients through the design, coordination, and planning stages of EWI projects. Below is a practical guide to help you understand when planning permission may be required and when it may not.

When planning permission is usually NOT required

In many cases, installing EWI on houses can fall under permitted development, meaning formal planning permission may not be required.

This is typically the case where:

• The building is not listed

• The property is not located within a conservation area

• The installation does not significantly change the external appearance in a way considered inappropriate by the local authority

• The insulation thickness and detailing remain proportionate to the existing building form

Even where permitted development applies, it is still good practice to obtain written confirmation from the local planning authority through a Lawful Development Certificate, particularly for larger or funded projects.

When planning permission is likely to be required

Planning permission is more likely to be needed where:

• The property is listed

• The building is located within a conservation area

• The façade forms part of a uniform streetscape where material changes may be controlled

• The insulation significantly alters the external appearance, building line, or architectural detailing

• The project involves multi-dwelling buildings, flats, or estate-wide upgrades

Another specific instance where planning may be required, is if the proposed External Wall Insulation will protrude by more than 16cm from the original wall.

Housing association and local authority retrofit programmes often require planning engagement early in the process, especially where aesthetic considerations or heritage constraints are involved.

A recent example of EWI with planning on one of our projects

A recent example is our work at The Retreat in Monmouthshire, where we delivered a deep retrofit programme across a row of bungalows that had previously suffered from poor thermal performance.

The project secured full planning approval for a coordinated package of upgrades, including External Wall Insulation (EWI), improved roof insulation, upgraded windows and doors, and associated external works.

By obtaining planning approval early and integrating the retrofit design strategy from the outset, the scheme progressed smoothly while significantly improving both energy efficiency and the long-term performance of the buildings.

Why planning should be considered early in retrofit design

EWI interacts with many other building elements including:

• Roof overhangs and eaves

• Window reveals and cills

• Rainwater goods and service penetrations

• Entrance canopies and façade detailing

• Boundary clearances and building lines

Because of this, planning considerations are often closely linked to the retrofit design strategy, not just the visual finish. Early coordination between retrofit designers, architects, and planning advisors helps avoid redesign, delays, and funding risks later in the programme.

Practical advice for landlords and housing providers

If you are considering EWI across a property or housing portfolio:

1. Check planning constraints early: Confirm whether the properties sit within conservation areas or have any heritage designations.

2. Engage your architect or planning consultant: They can advise whether permitted development applies or whether a planning application is recommended.

3. Coordinate planning with retrofit design: Planning drawings, façade treatments, and insulation specifications should be aligned from the outset.

4. Allow planning time in your programme: This helps avoid installation delays, especially for funded retrofit projects.

How Target Green supports EWI planning stages

Although we are not planning consultants, Target Green regularly works alongside architects, planning advisors, and local authorities to support the design, coordination, and technical delivery of EWI projects. Early involvement helps ensure that planning considerations, technical detailing, PAS 2035 requirements, and installation sequencing are aligned from the beginning.

If you are exploring an external wall insulation project and want early design input to understand feasibility, programme implications, and compliance considerations, our team is happy to discuss how we can support the process alongside your planning team.

Important note: Planning requirements vary between local authorities and individual sites. Always confirm requirements with your architect, planning consultant, or local planning authority before starting works.