Basement Conversion Pricing
Basement Conversion Pricing London
Basement conversion pricing in London decoded by local architects. Learn what’s worth the investment and how to avoid cost traps.
We prepare detailed Planning Applications, Building Regulation Drawings, and Structural Calculations to achieve consent for your project with our extensive knowledge and experience dealing with a basement conversion. Please see our fee guidelines below;
Basement Conversion Pricing London
Basement conversion pricing in London decoded by local architects. Learn what’s worth the investment and how to avoid cost traps. We prepare detailed Planning Applications, Building Regulation Drawings, and Structural Calculations to achieve consent for your project with our extensive knowledge and experience dealing with a basement conversion. Please see our fee guidelines below;
Site Survey
From £350
£0
- We provide a full measured site survey with photography
- Free site survey worth of £350 ( Discount end date 21.10.2025)
Planning Application Drawings
From £1,100
- Existing Floor Plans, Elevations and Sections to 1:50 or 1:100 scale @ A3
- Proposed Floor Plans, Elevations and Sections to 1:50 or 1:100 scale @ A3
- Prepare Ordnance Survey map, block plan and site plan
- Providing a design options to the client with full expert support and advice
- Electronic submission of the planning application, fill in application forms and CIL questions.via the Planning Portal ( Planning application Fee to the council not included)
- Management of the planning application including liaison with the Local Planning Authority until your application has been decided
- Existing Floor Plans, Elevations and Sections to 1:50 or 1:100 scale @ A3
- Proposed Floor Plans, Elevations and Sections to 1:50 or 1:100 scale @ A3
- Prepare Ordnance Survey map, block plan and site plan
- Providing a design options to the client with full expert support and advice Electronic submission of the planning application, fill in application forms and CIL
- questions.via the Planning Portal ( Planning application Fee to the council not included)
- Management of the planning application including liaison with the Local Planning Authority until your application has been decided
Structure Calculations
From £1,200
- Structural elements drawings (walls, beams, columns, foundation,roof etc.), including their size and design
- Structural elements drawings (walls, beams, columns, foundation,roof etc.), including their size and design
- Providing a design options to the client with full expert support and advice
Building Regulation Drawings
From £1,200
- Building Regulation Drawings with the details
- Structural calculation report
- We will complete building control application forms and act as your agent to your local council or private building control inspectorate
- Providing a design options to the client with full expert support and advice
Studio20 architects
Here’s what our clients have to say.
This was my first project and I was nervous at the beginning as every thing was new to us. Nadir was very helpful in guiding us through the entire project from planning stages to choosing materials to assigning builders; giving us assurances that the project would be finished on time and on budget. He also provided us with ideas for interior design. The build was of high quality with great care taken throughout. Geroge and his team were excellent builders and really gave us a peace of mind. There were issues with some of the materials (not their faults but due to Covid restrictions and the subcontractors), all of which were sorted out by Nadir and George between themselves. I’m hugely impressed by the after build care (nagging jobs and other issues). They were all addressed without fuzz.
A true test of a beautiful house is whether you are proud of showing it to guests. I’d say this project has passed this test with the highest score. We are still in love with the extension 3 years after it has finished. We’ve also received a lot of compliments from our guests.
I highly recommend both Nadir and George for their service.
Frequently Asked Questions – Basement Conversion Pricing
What affects the basement conversion price for my home?
The basement conversion price varies depending on site conditions, waterproofing requirements, structural support, access, and finish quality. Excavation depth, drainage solution,s and party wall agreements can also influence the final price. Early architectural input helps clarify these variables before build costs are confirmed.
How is the price of a basement conversion typically calculated?
The price of a basement conversion is usually estimated based on the project’s scale (size and complexity), the level of finishes you want, and the technical challenges involved. Most professional architects provide a detailed cost breakdown once they’ve completed a measured survey and concept design.
What is included in the basement conversion cost?
Your basement conversion cost typically includes design and planning fees, structural engineering, waterproofing systems, drainage, excavation, internal fittings, and finishes. Studio20 Architects can help you understand where each element fits into your budget and how to optimise cost without compromising quality.
Why does a basement conversion vary between practices?
A basement conversion company’s cost can vary because practices offer different levels of service, design quality, and technical support. Some firms include full project management, engineering coordination, and builder tender support, while others may only provide drawings. Transparent pricing from the outset helps you compare like-for-like services.
How can I get an accurate cost of a basement conversion estimate?
To get a reliable cost of a basement conversion estimate, you should start with a measured survey and concept design from an architect. Once the design parameters and technical requirements are clear, your architect can produce a tailored cost estimate — often before detailed planning or contractor tendering begins.
Does Studio20 provide a breakdown of the basement conversion price?
Yes. At Studio20 Architects, we explain how the basement conversion price is structured, from architectural design fees and planning support to technical drawings and build-stage consultancy. So you can make informed decisions at each stage of your project.
Can design decisions influence the basement conversion cost significantly?
Absolutely. Design elements like ceiling height, lightwells, waterproofing strategies, bespoke finishes, or structural solutions can affect the overall basement conversion cost. Working with an architect early helps balance design aspirations with realistic cost expectations.