Should you refurbish, extend or rebuild?
The best route depends on the building you have, the change you need and what is worth retaining. Answer a few questions to see which approach is the strongest starting point for your project.
Once we have suggested a route, enter the floor area and—where relevant—your specification level to get a simple rough-draft estimate. You can then explore the advantages and trade-offs of all three approaches before speaking with an architect.
- 01Find a directionShort project quiz
- 02Estimate the costQuestions for your route
- 03Review the trade-offsPros and cons explained
Step 1 · Recommendation quiz
Tell us what you want to achieve
Choose the answer that best reflects your plans. The quiz is designed to suggest a sensible option to investigate first—not to make a final technical or planning decision.
Your suggested starting point
Your recommendation
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Step 2 · Tailored cost estimate
Add a few details about your project
The questions below are tailored to your suggested route. An approximate area is fine.
Your rough draft estimate
Estimated project budget
Based on the project details you supplied.
| Cost component | Estimated amount |
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This is a rough draft estimate for initial guidance only. It is not entirely accurate, is not final, and is not a quotation or measured cost plan. Actual costs may vary with design, specification, surveys, site conditions, demolition, contractor pricing and the VAT treatment that applies to the project.
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Get help from proffesionals to suit your needs.
How we estimate costs and what is excluded
Understand the trade-offs
Each route has advantages and constraints. Open a section to explore what may matter for your building and brief.
Refurbish the existing building
Advantages
- Retains more of the existing building, character and embodied materials.
- Can be the most proportionate option when the structure is sound and the brief is mainly about updating.
- Work can sometimes be phased or focused on priority areas.
- May reduce demolition, waste and the amount of new construction required.
Trade-offs
- The existing layout, structure and building fabric place limits on what can be changed.
- Hidden defects, old services or hazardous materials may be discovered once work begins.
- Major structural changes can make a refurbishment less economical than first expected.
- It does not by itself create much new floor area.
Often worth exploring first when much of the building is serviceable and the main aim is to improve what is already there.
Extend the existing building
Advantages
- Adds useful floor area while retaining much of the existing property.
- Can improve connections between rooms, the garden, daylight and circulation.
- May avoid the need to relocate or replace the whole building.
- Can be combined with targeted refurbishment to address older parts of the property.
Trade-offs
- Foundations, roof junctions, openings and service connections can make small extensions costly per square metre.
- Plot size, neighbouring properties, drainage, access and planning rules can constrain the design.
- The new and existing buildings must work together technically and visually.
- Substantial expansion may be worth comparing with a new-build option.
Often worth exploring first when more floor area is a clear requirement and the existing structure is worth retaining.
Rebuild with a new design
Advantages
- Offers the greatest freedom to plan layout, structure, accessibility and performance together.
- Can avoid repeated repairs to a building with extensive defects or limitations.
- Creates a clear opportunity to coordinate insulation, services and long-term maintenance from the outset.
- May make it easier to align the whole building with a substantially changed brief.
Trade-offs
- Usually involves the largest upfront commitment and a longer, more complex project sequence.
- Demolition, waste removal, service disconnection and temporary arrangements add cost.
- Planning permission may not allow a replacement building of the size or form you want.
- Existing fabric is lost; heritage constraints, embodied carbon and VAT treatment need consideration.
Worth testing when the building is fundamentally unsuitable, retention is limited or the brief needs a completely new layout—subject to feasibility.
