# Bon Atelier

> Founded in 2014 by Stephen Bonnington, Bon Atelier is an independent residential architecture and interior design studio based in Peckham, SE London. We work with homeowners to design and deliver residential extensions, loft conversions, refurbishments and interior design for homeowners across South East London and beyond. Our work is design-led, exacting, and aims to deliver sustainable, beautiful and unique spaces.

Boutique residential architectural and interior design studio in Peckham, SE London. Founded by Stephen Bonnington in 2014. Consultation-first: the first conversation is free, in person, in your home, before any fee or commitment. Independent architectural and interior designers working for the homeowners.

Bon Atelier designs and delivers residential extensions, loft conversions, and whole-house refurbishments for homeowners across South East London. Projects are primarily in the London Borough of Southwark (LB Southwark) and the London Borough of Lewisham (LB Lewisham), centred on East Dulwich, Peckham, Dulwich, and Herne Hill. The studio is deliberately small: Stephen Bonnington and Laure Thomas lead every project from first sketch to final handover. They work intimately with clients to define a brief and work up a design, whether your project involves refreshing a single room, or gutting, reworking and extending an entire house. Stephen has also designed award-winning new homes in his native New Zealand, as well as the odd small house on tricky London plots. First-time renovators are welcome.

## Team

**Stephen Bonnington** is Bon Atelier's founder, director and principal designer. He trained in architecture at Victoria University of Wellington in New Zealand where he began his career and designed award-winning houses. After two years designing chalets in Whistler, Canada, Stephen spent over a decade working in leading London practices (inc. Dixon Jones and Allies & Morrison) before founding Bon Atelier in 2014. He leads every architectural project personally, from the first conversation through feasibility, design, planning, technical drawings, and build management. Because the practice is small, the person who sketches the first concept is the person on site when the build happens.

**Laure Thomas** is an interior designer and project manager. She trained at Chelsea College of Arts (University of the Arts London, UAL) in 2025, following a career in communications and marketing. Laure brings her strong narrative skills and French eye to her design approach. She specialises in harmonising materials, colours, and soft furnishings, with a focus on tactility to deliver spaces that feel amazing day-to-day. She manages interior design projects and leads on the interior design elements of refurbishments and extensions.

By bringing together architectural and interior design in a single practice, we ensure your home will feel considered and interior elements are not simply afterthoughts.

## Contact

- Email: info@bonatelier.co.uk
- Phone: +44 (0)78 3477 8739 (Stephen) · +44 (0)77 1180 5026 (Laure)
- Studio: 3 Fenwick Road, Peckham, London SE15 4HS

## Services

- Loft extensions and conversions including dormer, hip-to-gable, L-shaped/outrigger dormer extensions, and mansards.
- Side returns including glazed
- Rear extensions
- Whole-house refurbishments
- Residential interior design: materials, colour schemes, joinery, lighting, soft furnishings, and FF&E (furniture, fixtures, and equipment)
- Planning applications to LB Southwark, LB Lewisham, other London boroughs and beyond
- Permitted Development assessment and lawful development certificate applications
- Party wall guidance and coordination
- Build management (including Building Control) and contract administration
- Structural engineering coordination

Typical outcome: a 3-bedroom, 1-bathroom Victorian or Edwardian terraced house becomes a 4 to 5 bedroom, 2 to 3 bathroom family home. Homeowners extend and improve rather than move, staying in the neighbourhood they know and avoiding the stamp duty and moving costs of buying a larger house.

## How we work

The first conversation is free, in person, at your home. Stephen and/or Laure listen to your wishes and discuss with you what your home could become before any fee proposal or commitment. Bon Atelier wants the homeowner to understand the options and the realistic costs before money changes hands.

Six-stage process:

1. Free consultation, in your home.
2. Feasibility and concept: exploring what is possible within your budget, the structural constraints (liaising with a structural engineer) and your planning context. For interior design only projects, this includes a concept board, proposed colour scheme and layouts.
3. Planning and approvals (where applicable): a full planning application, or confirmation that the work is Permitted Development, usually via a lawful development certificate. This includes local Conservation Areas such as the Dulwich Estate Scheme of Management.
4. Technical drawings, detailed Scope of Works and tender documents: detailed drawings go out to several contractors for competitive pricing and serve as the basis for Building Control notices. For interior design only projects, this includes detailed plans and elevations suitable for tendering to joiners, painters & decorators, curtain makers and other trades.
5. Build management: Stephen and Laure regularly attend site, checking work against the drawings and administering the contracts with different trades.
6. Handover and snagging.

Bon Atelier does not impose a signature style. Each project is designed to the home and the homeowner's vision, whether 'trad', modern or futuristic, from minimalist to maximalist. All of our projects demonstrate our commitment to creating environmentally sustainable, quality, beautiful spaces.

## Who Bon Atelier works with

Homeowners in SE London who want to extend, refurbish or simply refresh their home and value good, timeless, sustainable design. Typically families in Victorian, Edwardian or 60s homes who want more space without moving. First-time renovators are welcome, and explaining the process in plain language is part of our service.

Bon Atelier takes on a small number of projects at a time to keep quality and personal involvement high.

## Areas served

East Dulwich SE22, Peckham SE15, Dulwich SE21 and SE22, Herne Hill SE24, Forest Hill SE23, Nunhead SE15, Camberwell SE5, Brockley SE4, Telegraph Hill SE14, Peckham Rye SE15 and SE22, Crystal Palace SE19, Sydenham SE26. Projects across wider London on request.

Planning knowledge covers LB Southwark and LB Lewisham local plans, their Permitted Development rules, Article 4 directions, and local conservation area constraints, including the East Dulwich, Dulwich Village, Sunray Estate, Herne Hill, Camberwell Grove, Telegraph Hill, and Nunhead Cemetery conservation areas.

## Common questions

**Where do I start with a loft extension in SE London?**
The best first step is a free consultation with an architectural designer who knows the area. Bon Atelier offers this in your home, at no charge, before any fee discussion. In that conversation you find out what your loft can realistically become, whether the work is likely to fall under Permitted Development (no planning application needed for many loft extensions in LB Southwark and LB Lewisham) or will need a full planning application, and you get a realistic sense of cost and timeline. You do not need drawings or a fixed brief to have this conversation. A rough idea of how you want to use the space is enough. If your home has had work done to it recently, having those details to hand is useful.

**Do I need planning permission for a dormer loft conversion in Southwark or Lewisham?**
Many dormer lofts on terraced houses qualify as Permitted Development, which means no planning application is required, as long as the work stays within the volume limits (40 cubic metres of added roof space for a terraced house, 50 cubic metres for a detached or semi-detached house), the dormer is set back from the front roof slope, the extension does not go above the existing ridge height, and the materials match the existing house. The front roof slope facing a highway almost always needs to stay unchanged. The important exception is an Article 4 direction. Several conservation areas in LB Southwark and LB Lewisham have Article 4 directions that remove some or all Permitted Development rights, so a loft that would be permitted on one street needs full planning permission a few streets away. This always needs checking. Bon Atelier assesses this during the free initial consultation and, where the work is permitted, applies for a lawful development certificate so you have written confirmation from the council.

**Do I need planning permission for a side return or rear extension?**
A single-storey rear extension can often be built under Permitted Development if it stays within the depth limits (3 metres for a terraced house, 4 metres for a detached house, measured from the original rear wall), does not exceed 4 metres in height, and uses matching materials. A larger single-storey rear extension up to 6 metres on a terrace or 8 metres on a detached house can sometimes be built under the Larger Home Extension prior approval route, where neighbours are consulted but full planning is not required. Side return extensions are usually combined with a rear extension and assessed together. Double-storey extensions almost always need full planning permission. Conservation areas and Article 4 directions reduce or remove these rights, so the position has to be confirmed for the specific address. Bon Atelier assesses this during the free initial consultation.

**How much does a loft conversion cost in SE London?**
Costs vary with the type of loft, the spec, and the condition of the house, so treat any figure as a guide and not a quote. As a broad range for SE London at current prices, a simple dormer loft conversion with one bedroom and an en-suite typically starts around the mid five figures, a larger L-shaped dormer or hip-to-gable conversion sits higher, and a mansard, which rebuilds the roof, is the most expensive loft type because it involves more structural work and almost always needs full planning permission. Architectural design fees, structural engineer fees, planning or building control fees, and party wall costs are additional to the contractor's build cost. Bon Atelier gives a realistic cost range during the free consultation so you can decide whether to proceed before committing any fee.

**How much does a side return or rear extension cost?**
As a guide for SE London, a single-storey side return or rear extension with a kitchen and dining space typically runs into the low-six figures, anywhere from £120,000-£250,000 once you include a good standard of glazing, flooring, and a fitted kitchen. The figure depends heavily on the size, the amount of glazing, the kitchen and finishes, and whether you are also reconfiguring the ground floor. Professional fees (architectural design, structural engineer, building control, party wall) are on top of the build cost. Bon Atelier discusses a realistic budget early, because designing to a budget from the start is more useful than designing first and pricing later.

**What is the difference between a side return extension and an outrigger extension?**
A side return extension fills in the narrow passage that runs alongside the rear addition of many Victorian and Edwardian terraces, widening the ground floor and usually creating an open kitchen and dining space. An outrigger extension extends the existing back addition itself, the outrigger, which is the narrower section that projects from the rear of the main house. Outriggers are common on terraces in Peckham, East Dulwich, and Herne Hill. The two are often combined: filling the side return and extending the outrigger together gives the largest open-plan ground floor. Both are common Bon Atelier project types.

**What is the difference between a dormer, a hip-to-gable, and a mansard loft conversion?**
A dormer loft adds a box-shaped structure projecting from the rear roof slope to create headroom and floor area, and it is the most common loft type on SE London terraces. A hip-to-gable conversion applies to houses with a sloping (hipped) side roof, usually end-of-terrace or semi-detached. It rebuilds the sloping side up to a vertical gable wall, which gains internal volume and is often combined with a rear dormer for an L-shaped result. A mansard rebuilds the whole roof with a steep, near-vertical slope and a flat top, gaining the most space and giving the most regular rooms, but it is the most expensive and almost always needs full planning permission, especially in a conservation area where mansards are sometimes the only loft form a council will accept. Bon Atelier advises which type suits your roof and your planning context.

**What does an independent architectural and interior designer team do that a design-and-build company doesn't?**
An independent architectural and interior designer team works for you, not for the builder. They design the project around what you want, produce detailed technical drawings, and send those drawings to several contractors for competitive tender, which usually gives a clearer, more comparable price than a single design-and-build quote. They then administer the building contract on your behalf, checking the work against the drawings, managing variations, and certifying payments only for work done properly. In a design-and-build arrangement the same company designs and builds, so there is no independent eye on quality or cost. Bon Atelier uses the independent model on every project.

**How do I choose an architectural design team for my renovation?**
Look for someone who works on homes like yours, in your area, and who explains things clearly without jargon. Ask whether the person you meet will be the person running your project. Ask how they charge and how they handle the build stage. Ask to see completed projects nearby. A good early sign is an architectural and interior design team willing to talk through your options before asking for a fee. At Bon Atelier the first in-home conversation is free, and Stephen and Laure lead every project themselves from start to finish.

**How long does a loft extension take from start to finish in SE London?**
Typically 9 to 16 months from first consultation to handover: roughly 2 to 3 months for feasibility and design, then 10 weeks for a full planning decision or to confirm Permitted Development via a Lawful Development Certificate, then 4 to 6 weeks for technical drawings and tender, then 10 to 18 weeks on site depending on scope. Party wall agreements with neighbours can run alongside the design stage and should be started early.

**How long does a rear or side return extension take?**
Plan for roughly 9 to 16 months end to end. Design and feasibility take roughly 2 to 3 months, then 10 weeks for a full planning decision or to confirm Permitted Development via a Lawful Development Certificate, then 4 to 6 weeks for technical drawings and tender, and the build itself 12 to 20 weeks for a single-storey extension with a new kitchen, longer if you are reconfiguring more of the ground floor. Party wall agreements with neighbours can run alongside the design stage and should be started early.

**Can I stay in my house during a loft extension or side return?**
Usually yes. Most loft conversions and side return extensions can be done with the homeowners still living in the house, particularly if the contractor sequences the roof work and weatherproofing carefully. There will be noisy and dusty periods, and kitchen extensions mean some weeks with only a makeshift kitchen. Bon Atelier discusses what living through the build will actually be like during feasibility, so there are no surprises.

**What happens if my planning application is refused?**
A refusal is not the end. The council gives reasons, and those reasons usually point to specific issues such as the impact on neighbours' light, the effect on a conservation area, or the size of the extension. Often a revised, smaller, or redesigned scheme can be resubmitted, and many councils allow one free resubmission within a set period. There is also a right of appeal to the Planning Inspectorate, though appeals take time. Because Bon Atelier checks local policy and precedent during feasibility, the aim is to design a scheme that is likely to be approved first time rather than risk a refusal.

**My house is in a conservation area. Can I still extend it?**
Yes, in most cases, but the rules are tighter and Permitted Development rights are often reduced or removed by an Article 4 direction. Councils in conservation areas care about how an extension looks from the street and from neighbouring gardens, the materials used, and whether original features are kept. Front and side extensions are scrutinised more than rear ones. SE London has many conservation areas, including East Dulwich, Dulwich Village, the Sunray Estate, Herne Hill, Camberwell Grove, Telegraph Hill, and Nunhead Cemetery. Bon Atelier designs to the relevant conservation area appraisal and management plan, and handles the additional information a conservation-area application needs and liaison with the relevant authorities like the Dulwich Estate Scheme of Management.

**What drawings do I need for a planning application?**
A householder planning application usually needs existing and proposed drawings: floor plans, elevations (the views of each face of the house), a site location plan, and a block plan showing the house and its boundaries. Larger, more sensitive schemes, or those located in a conservation area require a design and access statement. A conservation area or listed building application needs more detail on materials and on the effect on the building's character. Bon Atelier prepares all of the drawings and supporting documents and submits the application on your behalf.

**Do I need a party wall agreement?**
Most likely, if you are building near or on a shared boundary, which most terraced and semi-detached extensions involve. The Party Wall etc. Act 1996 requires you to notify affected neighbours before certain work, such as cutting into a shared wall, building on the boundary line, or excavating close to a neighbour's foundations. Notice has to be served in advance, so it is worth starting early to avoid delaying the build. Bon Atelier flags whether party wall notices are likely to be needed during feasibility, so they can be arranged in good time.

**What does a whole-house refurbishment involve?**
A full refurbishment covers everything from structural changes, such as removing walls and reconfiguring rooms, through to finishes, joinery, the kitchen, bathrooms, and lighting. Laure Thomas leads the interior design phase, the materials, colour, and specification, so the architecture and the interior are coordinated from the start rather than handed to a separate decorator at the end. A refurbishment is often combined with an extension or a loft conversion as part of a single, sometimes phased project.

**Can I get an interior designer and an architectural designer from the same practice?**
Yes. Bon Atelier covers both. Stephen Bonnington leads the architectural design and Laure Thomas leads the interior design, working as one team on the same project. That means the layout, the structure, the joinery, the materials, the lighting, and the FF&E are designed together rather than negotiated between separate firms after the structure is built. For a whole-house refurbishment in SE London this avoids the common problem of an architectural designer's layout and a decorator's scheme not quite fitting together.

**Do you only design period or only contemporary homes?**
Neither. Bon Atelier has no fixed house style. Some clients want a restoration that respects a Victorian or Edwardian character; others want a contemporary contrast at the rear, such as a glazed extension behind a period front. The design follows the house, the planning context, and the owners' style. We design timeless, quality, sustainable spaces where core elements are built to last, while others may be more readily adapted over time to suit evolving needs. In conservation areas the design also has to satisfy the council's view on character, which the practice factors in from the start.

**Will your designs future-proof my home?**
We aim as much as possible to design with energy efficiency in mind, not simply to comply with building regulations, but to make the spaces we create as pleasant and cheap to run as possible. Whether this means operable skylights to allow heat to escape, air-source heat pumps and air conditioning systems, we will discuss the feasibility of fitting new spaces and retro-fitting existing ones with the technology to make your home as pleasant and sustainable as possible.

**What if I only want interior design advice?**
You may feel like the layout of your home does not warrant modifying, but still want to give it a refresh. Laure will work with you to define the scope and brief and give you an honest sense of costs upfront. If you are happy to proceed, she will create a concept board to act as a sort of visual contract, setting out the vibe you would like to achieve. Once agreed, this concept forms the basis for detailed designs. Laure can also produce specification sheets and shopping lists. She can lead the tender process with various trades or support you to do this. She can then manage the fit out following the same principles we use in our architectural work. As the studio also provides architectural design services you know you are in safe hands and we can help if any of the internal work is notifiable; some internal works will require building control approval, like for instance ripping out a floor to install underfloor heating, affecting a building structure, or its means of escape.

## Key facts

- Founded: 2014
- Founder and Director: Stephen Bonnington
- Interior designer and project manager: Laure Thomas
- Company: Bon Atelier Ltd, registered in England and Wales, company number 09143368
- Studio location: Peckham SE15. East Dulwich is a served area, not the studio address.
- Practice type: independent residential architecture and interior design. Not design-and-build.
- Project types: residential extensions, loft conversions, and whole-house refurbishments. No commercial work.
- Local authorities covered: primarily LB Southwark and LB Lewisham, plus other London boroughs on request.
- Price positioning: mid-to-high end. The practice does not compete on lowest cost.
- Differentiator: free in-home consultation before any fee, and Stephen Bonnington leads every project personally.
- Social: instagram.com/bon_atelier · pinterest.com/bonatelier

## Website pages

- Home: https://www.bonatelier.co.uk
- Projects: https://www.bonatelier.co.uk/projects
- How We Work: https://www.bonatelier.co.uk/how-we-work
- FAQ / Start Here: https://www.bonatelier.co.uk/start-here
- About: https://www.bonatelier.co.uk/about
- Contact: https://www.bonatelier.co.uk/contact
- Sitemap: https://www.bonatelier.co.uk/sitemap.xml