Transparent, fixed-fee pricing for rear extensions, side returns, kitchen extensions and more across London and the South East.
Our single storey extension packages cover everything from the initial measured survey through to planning submission and structural engineering. All prices are fixed-fee with no hidden costs.
Accreditations & Education
Our team’s background combines architectural design, structural engineering and construction delivery.
Institution of Civil Engineers
The Institution of Structural Engineers
Academic excellence in the built environment
Academic excellence in design & innovation
Academic excellence in architecture & engineering
Institution of Civil Engineers
The Institution of Structural Engineers
Academic excellence in the built environment
Academic excellence in design & innovation
Academic excellence in architecture & engineering
Every package is designed to give you everything you need, with no surprises.
From your first enquiry to submission and support, our process is designed to keep your project clear, organised and moving forward.
An appointed surveyor will carry out a full measured survey of your property, noting down all your desired requirements for your proposal.
Your project is allocated to one of our architectural designers who will design it from the ground up, taking into account all your needs.
Your first draft is typically ready in 7 working days, and within 10 at the latest. Review the designs, send us any changes, and we’ll finalise your drawings for submission.
Your plans will be submitted strategically for swift council approval. Expect a decision in 6–8 weeks. We handle any required changes for free.
Once plans are approved, our Structural Engineers and Architects will manage the Structural Design and Building Regulations compliance. You can also get construction quotes from us to compare.
If you decide to build with us, we arrange a detailed consultation to finalise your requirements and ensure everything aligns perfectly with your vision.
Ready to start your project?
Get a Free ConsultationWhy Choose Us
From planning strategy to technical design and construction support, we combine practical experience with clear communication at every stage.
Our team brings extensive experience working with local authorities across London and beyond. From Lambeth to Hillingdon, we understand how different councils approach planning decisions.
We moved beyond 2D drawings years ago. Our 3D designs let you see the before and after of your property long before construction begins, so there are no surprises.
A dedicated project manager keeps your project on track with clear communication at every milestone. We maintain one of the fastest turnaround times in the industry.
Our guidance goes well beyond planning and architecture. We support you through the entire journey, from initial concept through to construction and completion.
Structural engineers, architectural designers and construction managers work side by side from day one, keeping your project coordinated, efficient and on brief.
With thousands of completed projects across our team, we bring deep expertise in residential design, structural engineering and the UK planning system.
Common questions about single storey extension pricing and our process.
Book a free consultation and get a fixed-fee quote for your project. No obligation, no pressure, just expert advice.
Share your project details and our team will review the scope, provide clear guidance, and come back with practical next steps — no obligation, just honest advice.
Extension, loft, new build — share your ideas using the form
Our architects assess your property and project requirements
Get a fixed-fee quote and a practical plan to move forward
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Speak with Salstan about your planning, architecture, structural engineering or building regulations project. We’ll help you understand the next steps and provide a clear, no-obligation quote.
We are a full-service, turnkey firm specialising in Architecture, Planning Permission, Building Regulations, Structural Design, Civil Engineering and Construction.
