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London Heritage: Tips for Listed Building Extensions 2025

Reading time: 10 minutes Author: Zak Gilby Date: 12 January 2025

Renovating a listed building is no small feat, especially in London where historic architecture is part of the city’s identity. While these projects can be incredibly rewarding, they also come with unique challenges. Whether you’re planning an extension, a conversion, or a full-scale refurbishment, understanding the complexities of listed building consent, listed building planning permission, and the regulations surrounding listed building extensions is essential. In this guide, we’ll walk you through the process, offering practical tips and showcasing how DeVis Architecture can help you turn your vision into reality.

In This Article:

1. What Is a Listed Building?
2. The Importance of Listed Building Consent
3. How to Get Listed Building Planning Permission
4. Challenges of Extending a Listed Building
5. Tips for Successful Listed Building Extensions
6. Types of Listed Building Extensions
7. Case Study: Listed Building Renovation in Wimbledon
8. Costs of Listed Building Extensions in 2025
9. What If I Don’t Get Listed Building Consent or Listed Building Planning Permission?
10. Building Control Exceptions for Listed Buildings
11. How DeVis Architecture Can Help
12. Conclusion & Next Steps!

What Is a Listed Building?

A listed building is one officially recognised as being of historical or architectural significance. These properties are protected under the Planning (Listed Buildings and Conservation Areas) Act 1990 to ensure their character and heritage are preserved for future generations.

Listed buildings fall into three categories:

  • Grade I: Buildings of exceptional interest (e.g., Buckingham Palace).
  • Grade II*: Particularly important buildings of more than special interest.
  • Grade II: Buildings of special interest, making up around 92% of all listed properties in England.

If your home is listed, any modifications – from replacing a window to adding an extension – will require listed building consent. Failure to comply can lead to severe penalties, including fines or even undoing unauthorised works.

Contemporary Conservation Area Extensions - Copper House - Listed Building Extensions
Contemporary Conservation Area Extensions – Copper House

The Importance of Listed Building Consent

Unlike regular planning permission, listed building consent is specific to alterations that affect the building’s character. This applies not only to external changes like extensions but also to internal modifications, such as removing walls or updating fixtures.

When applying for listed building consent, local planning authorities (LPAs) consider:

  • The historical and architectural significance of the building.
  • The impact of proposed changes on its character.
  • The materials and methods being proposed to ensure they align with the property’s heritage.

For example, replacing a timber sash window with a modern uPVC version would likely be rejected, as it undermines the building’s authenticity.

Traditional Conservation Area Wraparound Extension - Walnut House - Conservation Area Extensions
Traditional Conservation Area Wraparound Extension – Walnut House

How to Get Listed Building Planning Permission

In most cases, you’ll need both listed building consent and standard planning permission for extensions or significant works. The process involves submitting detailed plans to your local council, including:

  1. Drawings and Design Proposals: These should highlight how your project respects the building’s historical features.
  2. Heritage Impact Assessment: A report outlining how your plans will preserve the property’s heritage.
  3. Materials Specifications: Details of traditional materials and construction methods you’ll use.

At DeVis Architecture, we excel in crafting plans that meet these stringent requirements while maximising your property’s potential. Our experience with listed building extensions ensures we strike the perfect balance between modern functionality and historical integrity.

Challenges of Extending a Listed Building

Restrictions on Design and Materials

Planning authorities often insist on using traditional materials and techniques, which can drive up costs. For example, extending a Georgian terrace in London might require handmade bricks and lime mortar to match the original construction.

Limitations on Size and Placement

Extensions must complement the existing structure rather than overshadow it. This means a modern glass box extension might not get the green light, but a discreet rear extension with period-appropriate features could.

Conservation Area Overlap

Many listed buildings in London are also in conservation areas, adding another layer of regulations. In these cases, external changes that affect the area’s overall appearance will be scrutinised even further. Check if you are in a conservation area using our expert guide!

Contemporary Extension & Basement in a Conservation Area - Monument House - Conservation Area Extensions
Contemporary Extension & Basement in a Conservation Area – Monument House

Tips for Successful Listed Building Extensions

Engage Experts Early

Working with professionals experienced in listed buildings is non-negotiable. At DeVis Architecture, we work with expert heritage consultants who can guide you through the entire process, from initial designs to securing approval.

Understand the Property’s History

Researching your building’s historical significance can help you create a proposal that’s more likely to be approved. For example, if your property once had a particular architectural feature (like a garden room), restoring it as part of your extension could appeal to planners.

Communicate with the Local Planning Authority

Engage your local council’s conservation officer early to discuss your plans. Their feedback can help you refine your design and avoid costly delays.

Use Traditional Methods and Materials

Where possible, the LPA particularly appreciates incorporating original materials or high-quality replicas. This also ensures your extension feels like a natural evolution of the building rather than an afterthought.

Be Patient and Flexible

The process can be lengthy, with planning applications often taking 8–12 weeks or longer if revisions or further reports/investigations are needed. Keep an open mind and be prepared to adapt your plans to align with heritage requirements. Listed properties may not be ideal if you are a developer looking for a quick exit strategy.

Types of Listed Building Extensions

1. Rear Extensions

These are among the most common types of extensions for listed properties. Discreet rear additions such as a 3 meter house extension can offer extra living space without impacting the street-facing façade. Design elements such as in-keeping roof designs, timber-framed windows, and matching brickwork are often required. It is key to have a good idea of the house extension materials you are looking for before discussing with your design team.

2. Basement Conversions

Expanding downward is a popular option in London, particularly for Georgian and Victorian home extensions where there is limited outdoor space. However, basements in listed buildings can be complex cases due to concerns about structural integrity, services and drainage.

3. Linking Modern Additions

Glass connectors are a clever way to integrate modern home design ideas with historical structures. They preserve the original building’s character while adding a contemporary flair, and we find that local councils tend to prefer this option.

4. Loft Conversions

Loft conversions in listed buildings are subject to strict regulations, as permitted development cannot be utilised for typical dormer loft conversions or L-shaped loft conversions. Externally, dormer windows must blend seamlessly with the existing roof, while internally, historic beams or trusses may need to be retained, potentially disrupting your proposed new space.

Conservation Area House Extension Plans - Monument House - Conservation Area Extensions
Conservation Area House Extension Plans – Monument House

Case Study: Listed Building Renovation in London

One of our previous projects involved extending a Grade II listed property in London. The homeowners wanted to create an open-plan kitchen at the rear by means of a single storey rear extension. We worked closely with the local conservation officer and heritage consultant to design a single-storey extension that complemented the property’s Georgian aesthetic.

Key challenges included:

  • Specifying similar reclaimed bricks to match the original structure.
  • Maximising glazing to avoid impacting the original appearance.
  • Retaining original interior features, such as ceiling mouldings, and incorporating them into the new design.

The result was a seamless blend of old and new, providing the homeowners with a modern space that respects the building’s history.

Sleek Conservation Area Extension Design - Stage House - Listed Building Extensions
Sleek Conservation Area Extension Design – Stage House

Costs of Listed Building Extensions in 2025

Extending a listed building is often more expensive than extending a standard property due to:

  • Planning and Consent Fees: Applications for listed buildings typically require additional reports and more detailed drawings.
  • Specialist Contractors: Heritage projects demand skilled craftsmen familiar with traditional construction methods. If in doubt, ask your builders before starting!
  • High-Quality Materials: Using bespoke or reclaimed materials can significantly increase costs.

In London, you can expect to pay £2,500–£4,500 per square metre for a listed building extension, depending on complexity. For more details on costs take a look at our other blog on House Extension Costs for 2025!

What If I Don’t Get Listed Building Consent or Listed Building Planning Permission?

Renovating a listed building without obtaining the proper listed building consent or planning permission can have serious consequences, both legally and financially. Whilst it is possible to achieve retrospective planning permission, it cannot be guaranteed, so it’s advisable to go through the process beforehand. Listed buildings are protected to preserve their unique historical and architectural value, so any unauthorised changes – no matter how small – can lead to enforcement action.

Legal and Financial Repercussions

If you carry out work without consent, your local planning authority (LPA) could issue an enforcement notice requiring you to undo the changes. Restoring the building to its original condition can be extremely costly, especially if it involves removing modern materials and replacing them with heritage-approved ones. On top of that, you could face hefty fines or even prosecution, as unauthorised works to a listed building are treated as a criminal offence.

Devaluation of Your Property

Unauthorised changes can make it difficult to sell later on, and may also affect your property’s market value. Buyers and lenders may steer clear of a property with unresolved planning issues, fearing the potential costs of putting things right. Even if the changes seem minor, they can make selling the property more difficult and potentially lower its value instead of adding value.

Loss of Historical Charm

Listed buildings have unique character and heritage that unauthorised works can damage or erase. For example, swapping out traditional timber windows for modern uPVC ones might seem like a practical choice but could harm the building’s aesthetic and historical significance.

How to Avoid These Risks

Working with experts is key. At DeVis Architecture, we guide you through the planning process, liaising with conservation officers to ensure your project meets all the necessary requirements. With our help, you can achieve your dream renovation while preserving your property’s charm and avoiding unnecessary headaches.

Building Control Exceptions for Listed Buildings

Building Control requirements can be strict, but listed buildings often benefit from certain exceptions. Since these properties are legally protected under the Planning (Listed Buildings and Conservation Areas) Act 1990, preserving their historical character takes priority. For example, modern insulation standards of the current approved documents might be relaxed if they would compromise original features like timber-framed windows or decorative plasterwork.

These exceptions ensure that the building’s heritage isn’t lost to meet contemporary regulations. However, it’s not as simple as a free pass; you’ll still need to demonstrate with building regulations drawings that alternative solutions maintain safety and functionality. For instance, fire safety measures might be adapted to suit the building’s unique layout.

How DeVis Architecture Can Help

At DeVis Architecture, we specialise in creating bespoke designs for London’s most characterful homes. Our team has extensive experience navigating the challenges of listed building planning permission and listed building consent, ensuring your project runs smoothly from start to finish.

We pride ourselves on blending contemporary living with architectural heritage, delivering solutions that respect the past while embracing the future. Whether you’re planning a modest single storey rear extension or a complete home renovation, our tailored approach ensures your home’s unique character shines through.

Meet the Founders, Zak & Lina - DeVis Architecture
Meet the Founders, Zak & Lina – DeVis Architecture

Conclusion & Next Steps!

Renovating a listed building is a unique journey, combining creativity, patience, and an appreciation for history. By understanding the complexities of listed building consent, planning ahead, and partnering with the right experts, you can create a stunning space that balances modern functionality with timeless charm.

At DeVis Architecture, we’re here to make that journey as seamless as possible. If you’re considering a listed building extension or refurbishment in 2025, get in touch to discuss how we can help bring your vision to life.

FAQs

What is Listed Building Consent, and why do I need it?
Listed Building Consent is a legal requirement for any alterations that affect the character of a listed building, including extensions, conversions, or even minor internal changes. This consent ensures that your proposed works respect and preserve the building's historical and architectural significance. Without it, you risk enforcement action, hefty fines, or even having to reverse the changes. At DeVis Architecture, we guide you through this process, liaising with conservation officers to create designs that align with heritage requirements while fulfilling your vision. Securing consent is essential to protect your property’s value and avoid legal complications.
Can I extend my listed building without compromising its character?
Yes, you can extend a listed building while preserving its character with the right design approach. The key is to ensure the extension complements the original structure using period-appropriate materials and styles. Modern features, like glass connectors, can also work if they clearly distinguish old from new. At DeVis Architecture, we specialise in blending contemporary functionality with historic charm, creating bespoke designs that meet planning requirements. By working with experienced professionals and consulting your local conservation officer, you can achieve a harmonious extension that enhances your home’s value and usability without losing its heritage appeal.
What challenges might I face when extending a listed building?
Extending a listed building involves unique challenges, such as stricter planning regulations, the need for listed building consent, and higher costs for using traditional materials and skilled craftsmen. You may face limitations on size, placement, and design to ensure the extension blends seamlessly with the original structure. Conservation officers often scrutinise proposed changes to protect the building’s character. However, with proper planning, patience, and expert guidance, these challenges can be overcome. DeVis Architecture helps navigate these complexities, delivering designs that respect your property’s heritage while meeting modern living needs.
How long does the listed building consent process take?
The listed building consent process typically takes 8–12 weeks from submission, but this can vary depending on the complexity of your project and local authority workload. Delays may occur if additional reports, such as a Heritage Impact Assessment, are required or if revisions are needed to meet conservation officer feedback. To streamline the process, it’s crucial to provide detailed, accurate plans from the outset. At DeVis Architecture, we ensure your application is comprehensive and tailored to heritage requirements, helping to minimise delays and secure approval as efficiently as possible. Planning ahead is key to a successful project timeline.
Interested? Contact Us Today!
Interested? Contact Us Today!
We are located at:
7a Holland Road, Kensington, London W14 8HJ

Call or email us at:
+44 (0) 7494 162409
info@devisarchitecture.com
We are located at:
7a Holland Road, Kensington, London W14 8HJ
Call or email us at:
+44 (0) 7494 162409
info@devisarchitecture.com
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