House Extension Design Services
MCIAT-Chartered Design. 350 Planning Approvals. Sussex & Surrey.
Why Sussex and Surrey Homeowners Choose ArchEvolve
- 15 years of experience
- 350 planning approvals secured
- 500 projects completed
- Revit 3D modelling as standard
- MCIAT-chartered accreditation
Every Type of House Extension, Designed In-House
House Extension Design: Where Most Projects Go Wrong
Common challenges
- Planning refusals from designs that ignore local policy
- Extensions that lose light and feel like an afterthought
- Slow revisions from designers still working in 2D CAD
- Building Regulations issues caught after construction starts
- Fees that creep past the original quote
- Designers with no professional accreditation or indemnity insurance
How ArchEvolve solves them
- Extension designs built around your local council’s planning policy
- Space planning that prioritises light, flow and how you actually live
- Revit 3D workflow for fast, accurate revisions before submission
- Full Building Regulations drawings produced in-house
- MCIAT-chartered accreditation with professional indemnity
- MCIAT-chartered accreditation with professional indemnity
How an ArchEvolve Project Works
Initial Consultation
Feasibility Assessment
Concept Design
Planning Application
Building Regulations
Construction Drawings
Construction Support
years of experience
Planning approvals
projects completed
largest construction project developed
Proudly Serving Homeowners Across Sussex and Surrey
A Different Standard of Design for House Extensions in Sussex and Surrey
3D Visualisations Included
Every house extension project is modelled in Revit and rendered in Enscape. You see accurate light, materials and spatial quality before a planning application goes in.
Faster Planning Submissions
Drawings produced in a coordinated 3D environment are more complete and less prone to officer queries, which keeps your house extension timeline on track.
Local Planning Knowledge
ArchEvolve has submitted house extension applications across West Sussex, East Sussex and Surrey planning authorities. Your submission is prepared for the specific council from day one.
End-to-End Service
From feasibility through to construction drawings, Alex Page manages every stage of your house extension project personally. No handoffs, no junior staff taking over mid-project.
House Extension Design Across Sussex and Surrey
Many single storey rear extensions fall under permitted development and do not require a full planning application, but this depends on the size, your property type and any existing extensions. Larger extensions, side extensions, and properties in conservation areas usually need full planning permission. Our planning permission guide covers the thresholds in detail, and ArchEvolve confirms your specific position at the free initial consultation before any design fees are committed.
Design fees depend on the size and complexity of the extension, and whether the project also needs Building Regulations and construction drawings. ArchEvolve agrees fixed-scope fees in writing before any work begins, so there are no surprises. For typical build cost ranges, see our house extension cost guide.
In most cases, yes, provided the extension is well designed and proportionate to the property. Poorly planned extensions that reduce garden space or create awkward layouts can have the opposite effect. Our article on whether a house extension adds value breaks down the factors that matter most.
Design and planning typically take 8 to 13 weeks depending on your council’s determination period, with Building Regulations and construction drawings running in parallel once planning is granted. Construction time depends on the scope of the extension and your chosen contractor. ArchEvolve manages the design and approvals stages so your project reaches site as quickly as the process allows.
The service covers feasibility assessment, concept design in Revit with Enscape renders, planning application preparation and submission, full Building Regulations drawings, and construction drawings your builder can quote and build from. Support continues through the construction phase for queries and drawing updates.
Extension costs can escalate through structural surveys, party wall matters, drainage diversions and unforeseen ground conditions. Our guide to the hidden costs of a house extension sets these out clearly so they can be planned for from the outset rather than discovered mid-build.
ArchEvolve is based in Rustington and designs house extensions across West Sussex, East Sussex and Surrey, including Worthing, Horsham, Chichester, Crawley, Guildford and Brighton. A free initial consultation is offered to homeowners throughout the region.
Frequently Asked Questions
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