Essential Guide to Double Storey Extension Seven Dials: Design & Costs

A double‑storey extension is one of the most powerful ways to expand your living space, avoid moving, and increase value — but it’s complex. In this post, we walk you through the design considerations, cost drivers, planning steps, and practical tips specifically for a double-storey extension in a location like Seven Dials.

Introduction to Home Extensions

A double storey extension is a great way to add space to your existing house without sacrificing garden space.
Double storey extensions offer more living area and can increase the value of your property.
When planning a double storey extension, consider the design, cost, and building regulations.
It’s essential to work with a reliable builder and architectural team to ensure a successful project.
Double storey extensions can be a cost-effective way to expand your home, especially when compared to single storey extensions.

Double Storey Extension Seven Dials: Benefits of Extending Your Home

Extending your home can provide additional space for a growing family or changing lifestyle.
A double storey extension can add a new bedroom, bathroom, or living area to your existing house.
Double storey extensions can also increase the natural light and ventilation in your home.
With careful planning, a double storey extension can be designed to blend seamlessly with the existing building.
A well-designed extension can also enhance the exterior of your property and increase its value.

Types of Home Extensions

There are several types of home extensions, including single storey and double storey extensions.
Double storey extensions are ideal for homes with limited garden space, as they provide additional space without taking up too much land.
Two storey extensions can be built to the rear or side of the existing house, depending on the design and planning permissions.
It’s essential to consider the roof pitch and eaves height when designing a double storey extension to ensure it complies with building regulations.
A double storey extension can be a more cost-effective option than moving to a new house.

Extension Options

When planning a double storey extension, consider the available space and the design of the existing house.
A double storey extension can be built to the rear, side, or even as a wraparound extension, depending on the available land and planning permissions.
It’s essential to work with an architectural team to design an extension that complements the existing building and meets your needs.
Double storey extensions can be designed to include additional features such as balconies, although these may require additional planning permissions.
A well-designed extension can enhance the overall appearance of your property and increase its value.

Planning and Permission

Planning permission is required for most double storey extensions, especially if they exceed certain limits and conditions.
It’s essential to check with your local authority to determine if planning permission is required for your double storey extension.
Permitted development rights allow for some extensions to be built without planning permission, but these rights are subject to certain restrictions.
Conservation areas and national parks have stricter planning rules, and it’s essential to work with planning consultants to ensure compliance.
A reliable builder can help guide you through the planning and permission process.

Building Regulations and Compliance

Building regulations approval is mandatory for all double storey extensions to ensure they are structurally sound and meet safety standards.
It’s essential to work with a reliable builder who is familiar with building regulations and can ensure compliance.
Building control fees apply to all double storey extensions, and these fees vary depending on the local authority.
A double storey extension must be designed and built to meet the required building regulations, including those related to insulation, drainage, and fire safety.
Regular inspections and testing are necessary to ensure the extension meets the required standards.

Party Wall Considerations

A party wall agreement may be required if your double storey extension is built near a boundary or shared wall.
It’s essential to work with a reliable builder who is familiar with party wall agreements and can guide you through the process.
Party wall agreements can help prevent disputes with neighbours and ensure a smooth construction process.
A party wall agreement can also help protect your interests and ensure that the extension is built to the required standards.
Neighbours must be notified and agree to the party wall agreement before construction can begin.

Working with a Reliable Builder

A reliable builder is essential for a successful double storey extension project.
It’s essential to work with a builder who is familiar with double storey extensions and has experience with similar projects.
A reliable builder can guide you through the construction process, ensure compliance with building regulations, and provide a high-quality finish.
When selecting a builder, consider their reputation, experience, and previous work.
A reliable builder can also help you navigate the planning and permission process.

Understanding the Costs

The cost of a double storey extension varies depending on the design, materials, and location.
On average, the cost of a double storey extension can range from £1,500 to £2,500 per square metre.
It’s essential to work with a reliable builder who can provide a detailed breakdown of the costs and help you stay within your budget.
Additional costs such as building control fees, party wall agreements, and planning permissions should also be considered.
A double storey extension can be a cost-effective way to expand your home, especially when compared to moving to a new house.

Conservation Area Considerations

Conservation areas have stricter planning rules, and it’s essential to work with planning consultants to ensure compliance.
The design of the extension should consider the local authority’s conservation area policies and restrictions.
It’s essential to preserve the character and appearance of the conservation area when designing a double storey extension.
A reliable builder can help guide you through the conservation area considerations and ensure compliance.
Additional restrictions may apply to listed buildings or properties in areas of outstanding natural beauty.

Project Management and Timeline

A double storey extension project can take several months to complete, depending on the complexity of the design and the construction process.
It’s essential to work with a reliable builder who can provide a detailed project timeline and manage the construction process.
Regular inspections and testing are necessary to ensure the extension meets the required standards.
A reliable builder can help guide you through the project management process and ensure a smooth construction process.
Delays can occur due to weather conditions, material availability, or unforeseen site issues.

Pre-Construction Preparation

Pre-construction preparation is essential for a successful double storey extension project.
It’s essential to work with a reliable builder who can guide you through the preparation process.
The preparation process includes obtaining planning permission, building regulations approval, and party wall agreements.
A reliable builder can help ensure that all necessary preparations are made before construction begins.
Site preparation, including demolition and excavation, must be carefully planned and executed.

Inspections and Testing

Regular inspections and testing are necessary to ensure the extension meets the required standards.
It’s essential to work with a reliable builder who can guide you through the inspection and testing process.
The inspections and testing include checks on the foundation, framing, roofing, and installation of windows and doors.
A reliable builder can help ensure that all necessary inspections and testing are completed before the project is finished.
Final inspections are crucial to ensure the extension is safe and meets the required standards.

Warranty and Maintenance

A reliable builder should provide a warranty for the double storey extension, which typically ranges from 1 to 10 years.
It’s essential to understand the terms and conditions of the warranty and what is covered.
Regular maintenance is necessary to ensure the extension remains safe and meets the required standards.
A reliable builder can help guide you through the maintenance process and provide advice on future repairs.
Maintenance costs should be factored into your budget, and a reliable builder can provide guidance on expected costs.

Party Wall Agreement

A Party Wall Agreement (or Party Wall Award) is a legal document required under the Party Wall etc. Act 1996 (UK) when you carry out certain types of building work that affect a shared wall, boundary, or structure with a neighbour.

What Is a Party Wall?

A party wall is a wall shared by two properties — typically in semi-detached or terraced houses. It can also include:

Shared floors/ceilings between flats
Boundary walls between two gardens (built astride the boundary line)
Any structure near (within 3 or 6 metres) of a neighbour’s property where foundations may affect theirs

Party Wall Process (Step-by-Step)

Serve Notice: You must serve written notice to your neighbour(s) at least 2 months before work begins.
Wait for Response:
- If they consent in writing, you can proceed — but it’s best to record the building condition first (Schedule of Condition).
- If they dissent or don’t respond in 14 days, a Party Wall Award must be agreed (see below).
Appoint Surveyor(s):
- Each party can appoint their own surveyor (you pay for both unless neighbours agree to use the same one).
- The surveyor(s) will prepare a Party Wall Award — this sets out what work is allowed, how it must be done, and protections for both parties.
Work Can Start: Once the Award is finalised, work can begin — but you must follow all conditions set by the surveyor(s).

Building Control Fees

Building Control Fees are the charges paid to your local authority (or an approved private inspector) to inspect and approve your construction work to ensure it complies with UK Building Regulations.

What Do Building Control Fees Cover?

Building Control ensures your project is safe, structurally sound, energy efficient, and meets UK legal standards. The fee typically covers:

Plan checking – reviewing your architectural & structural drawings
Site inspections – at key stages like foundations, drainage, insulation, roofing, etc.
Final sign-off – when work is complete and meets all regulations

You must either go through:

Your Local Authority Building Control (LABC), or
A private Approved Inspector (who may charge differently)

Single Storey Extension

A single storey extension adds extra space to your home on ground level only — typically at the rear, side, or wrapping around the corner.

Common uses:

Kitchen-diners
Utility rooms
Living space extensions
Ground floor bathrooms or home offices

Pros of a Single Storey Extension

More straightforward than double-storey (less structural work)
Often permitted development
Less disruption to upstairs rooms
Usually cheaper per square metre to build

What is Permitted Development?

Permitted Development Rights are granted by national legislation (The Town and Country Planning Act) and let homeowners carry out specific types of work without applying for formal planning permission — as long as the work meets strict size, height, location, and design rules.

It applies mainly to houses, not flats or maisonettes, and excludes listed buildings or homes in conservation areas (e.g. parts of London like Seven Dials, Bloomsbury, or Covent Garden may have restrictions).

What’s Not Allowed Under Permitted Development?

You’ll likely need full planning permission if:

You live in a listed building, flat, or conservation area
Your extension is too large, tall, or close to a boundary
You want a wraparound extension (rear + side)
You’re adding a balcony, veranda, or raised terrace
The extension would result in covering more than 50% of your garden

Final Thoughts: Making the Most of Your Double Storey Extension in Seven Dials

A double-storey extension is a bold yet rewarding move—offering you more space, higher property value, and the opportunity to truly customise your home to your lifestyle. In a tightly packed urban area like Seven Dials, it can be a smart alternative to moving, especially with rising property prices and the costs associated with relocation.

However, success depends on three critical factors:

Thoughtful Design – Work with an experienced architect who understands both aesthetics and practical layout. The best extensions feel seamless and intentional.
Realistic Budgeting – Include a proper contingency, and be prepared for higher costs in areas with tight access or planning constraints.
Expert Project Management – From party wall notices to planning permissions and contractor coordination, staying organised can make or break the experience.

If you’re in Seven Dials and considering a double-storey extension, treat it as both a home upgrade and an investment decision. With the right team and planning, you can unlock new potential in your property—and enjoy the process along the way.

FAQs

1. Do I need planning permission for a double-storey extension in Seven Dials?

Yes, in most cases.
While some extensions may fall under Permitted Development Rights, double-storey builds often exceed the limitations—especially in urban or conservation areas like Seven Dials. Always check with your local planning authority or consult an architect before starting.

2. How long does a double-storey extension take to complete?

Typically 6 to 12 months from design to finish.
This includes:

1–3 months for design and planning approval
1–2 months for contractor tendering
3–5+ months for on-site construction
Larger or more complex projects (or those in tight urban areas) may take longer.

3. How much does a double-storey extension cost in Seven Dials?

Expect £2,000 to £3,000 per square metre as a general guide (excluding high-end finishes).
For example, a 60 m² extension (30 m² on each floor) might cost between £120,000 and £180,000+, depending on design, access, and specification level. Always budget an extra 10–15% for unforeseen costs.

4. Will a double-storey extension add value to my property?

Yes, often significantly.
In high-demand areas like Seven Dials, increasing your home’s usable space—especially bedrooms and bathrooms—can greatly boost market value. However, overcapitalising (spending more than you’ll recoup) is a risk if the extension exceeds the area’s price ceiling.

5. Can I live in my home during the construction?

Sometimes—but expect disruption.
If the extension is at the rear or side, and structural alterations are limited, you might be able to remain in part of the home. However, there will be dust, noise, and possible utility shutoffs. Many families choose to move out temporarily during heavy works.

You can find more information on our website, Create