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Extension Design Specialists
Fixed-fee from £1,950 + VAT Fixed-fee from £1,950 + VAT · Start for just £250 + VAT deposit
Understand whether your project is likely to gain permission, what it may cost, and what the process involves.
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Mr & Mrs Andrews, Winchester
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“Excellent service from start to finish. Mark was responsive, professional and delivered exactly what we needed.”
— Andrew Stone Read on Google ↗
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Fixed-Fee Packages
Planning drawings and building regulations for single-storey, double-storey extensions and loft conversions. Serving Hampshire, Hertfordshire, Surrey, Oxfordshire, Buckinghamshire & surrounding counties. Fixed-fee pricing, transparent from day one. Try our Free Feasibility Study.
Fixed-fee packages
Three clear scopes. One measured survey. Our work ends before construction begins.
Pre-Build Package
Planning & Building Notice Drawings
£1,950 + VAT
Premium Package
Contractor Tender & Client Contract
£2,950 + VAT
Premium Plus Package
Contract, Notices & Build Programme
£3,950 + VAT
Prefer to talk first? Book a call
Three structural revision rounds are included. Any additional round is £450 + VAT, only with your prior written approval.
At a glance
Choose a package for a clear scope, then add only what your project needs.
| Package contents | Pre-Build £1,950 + VAT | Premium £2,950 + VAT | Premium Plus £3,950 + VAT |
|---|---|---|---|
| Design & planning | |||
| Professional on-site measured survey | |||
| Detailed planning drawings | |||
| Planning application submission (council fee paid separately) | |||
| Building regulation drawings prepared for Building Notice submission | |||
| Structural calculations by an independent qualified structural engineer | |||
| Structural revisions | 3 rounds | 3 rounds | 3 rounds |
| Contract & tender | |||
| Detailed schedule of works | + £1,000 | ||
| Contractor vetting and two cost proposals | in + £1,000 | ||
| Client-focused building contract (payments in arrears) | in + £1,000 | ||
| Staged programme of works | + £750 | + £750 | Included |
| Notices & agreements | |||
| Building Notice submission (council fee excluded) | + £450 | + £450 | Included |
| Party Wall notice (per adjoining owner) | + £250 | + £250 | 1 included |
| Build Over Agreement (water company fees excluded) | + £650 | + £650 | + £650 |
All prices exclude VAT. “+ £” items can be added to any package as fixed-fee extras.
Scope add-ons: loft conversion combined with an extension + £950; two-storey extension + £750; internal reconfiguration + £750. Standalone loft conversions are the package fee only.
Additional structural revision rounds: £450 + VAT per round beyond the three included rounds, only with your prior written approval (Terms & Conditions 10.6). They are not part of an initial package quote.
Our service ends before work starts on site. Council, planning application, water company and Party Wall surveyor fees are not included. Full terms at hampshirebuild.co.uk/terms (Version 2.9).
98% planning approval rate. Planning approval cannot be guaranteed. Approval is always the local authority's decision. Council and planning application fees are paid separately, directly to the local authority.
Free Feasibility Study
Answer a few questions and get your free feasibility summary — planning route, build costs and local values.
Essential services to support your extension project. Click to enquire.
Legally compliant party wall notices prepared and served under the Party Wall Act 1996. Required before building near boundaries or shared walls.
Complete build over agreement application with drainage drawings. Required when building over or near public sewers.
We prepare and serve your Building Notice on the local authority. Council building control fees are paid separately.
Preliminary Ecological Appraisal for planning applications. Required when your site may contain protected species or habitats - common for loft conversions, extensions near trees or hedgerows.
Comprehensive Flood Risk Assessment for planning applications. Required when your property is in a flood zone. Includes site analysis, flood zone mapping, mitigation measures and full FRA report for submission.
Understanding what's possible before you commit - our comprehensive 30-minute video call consultation covers all the essentials
Professional cost assessment based on current square metre rates for shell and core builds, giving you realistic budget expectations for your extension project.
Quick professional review to verify adequate land area for your proposed building extension, ensuring your project is physically viable on your property.
We check publicly available planning history for your property and surrounding area, helping to identify potential opportunities and constraints before we begin the design process.
Realistic cost estimates based on current market rates and your specific requirements
Clear understanding of what's physically possible on your property
Early identification of planning opportunities and potential constraints
Clear roadmap for moving forward with your extension project confidently
Book your complimentary 30-minute feasibility assessment and realise what's possible for your home
No obligation • Professional advice • Video call consultation
Why Hampshire Build
With over 20 years of residential design expertise, we deliver exceptional extension design services with transparent fixed-fee pricing and rigorous attention to quality on every project.
Over 20 years of residential design expertise with successful projects across Hampshire, Hertfordshire, Surrey, Oxfordshire, Buckinghamshire and beyond.
Fixed fees for defined package scopes from £1,950 (Pre-Build) to £3,950 (Premium Plus). Statutory fees and third-party costs are separate.
The survey and drawing schedule is agreed after instruction. Project timing depends on the scope, client input and third-party processes.
Packages include a measured survey, planning drawings and application submission, Building Notice drawings and required structural calculations by an independent qualified structural engineer. Construction-phase services are not included.
Our Track Record
Extensions Designed
Years of Experience
Google Rating
Ready When You Are
Join 150+ families who chose Hampshire Build. Book your complimentary consultation today.
No obligation · 30-minute video call · Professional advice
Rated 5.0 on Google
"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, Winchester
"Excellent service from start to finish. Our original architect continually let us down, but Mark at Hampshire Build was responsive, professional and delivered exactly what we needed for our extension project."
— Andrew Stone, Hampshire
"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, Surrey
Fixed-fee planning drawings and building regulations for homeowners across Hampshire and beyond. Click your town for local planning guidance and project examples.
How It Works
From initial survey to final technical drawings — we've streamlined the extension design process to deliver professional results quickly and efficiently.
At consultation
Discuss your project requirements and choose your fixed-fee package. Pay £250 + VAT (£300) deposit to begin.
Survey and design schedule
Survey and drawing dates are agreed with you after instruction.
We review the first drawings with you and develop the design from your feedback.
Following Your Feedback
Design consultation to finalise drawings, then planning submission and technical documentation.
Survey timing agreed after instruction
Drawing schedule agreed after survey
Payment schedules for each package are set out in our Terms & Conditions.
Begin your extension journey today with our streamlined process and transparent pricing.
