Expert Extension Design — Fixed Fee, No Surprises
Specialist extension designers. Fixed-fee packages from £1,950 + VAT. Planning drawings, building regulation drawings prepared for Building Notice submission, and structural calculations by an independent qualified structural engineer.
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Designed around you
A clear route to planning and Building Notice drawings.
What We Do
The Pre-Build Package
Hampshire Build provides a defined fixed-fee design package for residential extensions, covering measured survey, planning drawings and application submission, and building regulation drawings prepared for Building Notice submission with required structural calculations from an independent qualified structural engineer. Planning decisions are made by the local authority.
We are designers, not builders. Our focus is design, drawings, and planning — giving you the professional documentation you need to get planning permission and instruct a contractor with confidence.
Planning Drawings & Application
Site plan, floor plans, and elevations drawn to planning authority standards. We submit the full application on your behalf.
Building Regulations Drawings
Building regulation drawings prepared for Building Notice submission, with structural calculations by an independent qualified structural engineer.
Contractor Tender Management
Premium Package clients receive a detailed schedule of works and tender documentation sent to two vetted contractors — with a proposal comparison so you can make an informed decision.
Transparent Pricing
Three Fixed-Fee Packages
All prices exclude VAT. No hidden costs — the fee you see is the fee you pay for the specified scope.
Pre-Build Package
Planning & Building Notice drawings
- Professional on-site measured survey
- Planning drawings and application submission
- Building regulation drawings
- Independent qualified structural engineer calculations
Premium Package
Design & tender support
- Everything in Pre-Build Package, plus:
- Detailed schedule of works
- Contractor vetting and two proposals
- Client-focused building contract
Premium Plus Package
Contract, Notices & Build Programme
- Everything in Premium Package, plus:
- Staged programme mapped to contractor payments
- Building Notice submission
- One Party Wall notice to one adjoining owner
All packages include one on-site measured survey. See full terms.
Why Choose Us
The Hampshire Build Difference
Your package price is fixed. No hourly billing surprises — you know exactly what you'll pay.
Design only — no build markup. We have no commercial interest in who builds your extension.
Design reviews by phone or video call — flexible, efficient, and built into the fixed fee.
We agree the survey and drawing schedule with you after instruction.
Hampshire, Hertfordshire, Surrey, Berkshire, Buckinghamshire, Oxfordshire, West Sussex & Wiltshire.
How It Works
Four Simple Steps
Complimentary Consultation
Discuss your project, budget, and vision. We assess feasibility and advise on the right package — no commitment required.
Measured Survey
We arrange a measured survey as part of the design process; the schedule is agreed after instruction.
Design & Planning
Your drawings are produced and the planning application submitted to your local authority.
Building Regulations
Building regulation drawings are prepared for Building Notice submission, with structural calculations prepared by an independent qualified structural engineer.
Client Reviews
What Our Clients Say
"Thank you Mark, we have really appreciated how prompt you have been with responding to emails and calls whilst we have been going through design and planning stages. Your reassurance, reliability and professionalism have been a great help."
Sandra Trott
"Excellent service from start to finish."
Andrew Stone
"Mark & his team were brilliant in helping us finish off our build — they were kind, efficient and have done a great job. Will definitely be using them again in the future for any work!"
Charlie Brenninkmeijer
Where We Work
Service Areas
We cover eight counties across South and South-East England. Click your county for local information.
Common Questions
Extension Design — FAQ
How much does extension design cost in Hampshire?
Do I need professional architectural design for a house extension?
How long does planning permission take in Hampshire?
What is included in a fixed-fee extension design package?
Do you need building regulations drawings for an extension?
Ready to Get Started?
Book a complimentary consultation and discuss your project with us. No commitment — we'll assess feasibility and confirm which package is right for you.
Or email us at info@hampshirebuild.co.uk