Extend vs Move House London 2025: Cost Comparison & Guide
Should you extend your home or move? Complete cost comparison including 2025 stamp duty changes, hidden moving costs, extension ROI, and decision framework.
Extend vs Move: Quick Comparison
- Moving costs: £36k-50k+ (stamp duty £21k + fees £15k-30k)
- Extension costs: £40k-60k for 20m² quality extension
- Extension ROI: Adds 15-25% property value (80-150% return)
- 2025 stamp duty: Thresholds reduced - home movers hit harder
- Get your extension cost estimate (Free)
The True Cost of Moving House in London (2025)
The average London property price is £543,370. After April 2025 stamp duty changes, moving became significantly more expensive.
2025 Stamp Duty Changes
| Threshold | Before April 2025 | After April 2025 |
|---|---|---|
| First-time buyer | £425,000 | £300,000 |
| Home mover | £250,000 | £125,000 |
Complete Moving Costs Breakdown
| Cost Item | £543k Property | £750k Property |
|---|---|---|
| Stamp duty (2025 rates) | £21,650 | £32,500 |
| Estate agent fees (1.5%) | £8,150 | £11,250 |
| Solicitor fees (both sides) | £3,000-6,000 | £3,500-7,000 |
| Surveys & searches | £800-2,000 | £1,000-2,500 |
| Removals | £1,000-2,000 | £1,200-2,500 |
| Mortgage fees | £1,000-2,000 | £1,500-2,500 |
| Overlap costs/temp housing | £2,000-5,000 | £3,000-6,000 |
| TOTAL MOVING COSTS | £37,600-46,800 | £53,950-64,250 |
Key insight: Just to move laterally (same value property), you'll spend £37k-47k minimum. This doesn't include any actual upgrade in property value.
Extension Costs vs Space Gained
| Extension Type | Space Gained | Total Cost | Value Added |
|---|---|---|---|
| Single-storey rear (20m²) | 20m² (215 sq ft) | £40,000-60,000 | £40,000-80,000 |
| Side return (12m²) | 12m² (129 sq ft) | £30,000-45,000 | £35,000-65,000 |
| Two-storey rear (40m²) | 40m² (430 sq ft) | £88,000-120,000 | £80,000-140,000 |
| Loft conversion (30m²) | 30m² (323 sq ft) | £54,000-75,000 | £40,000-70,000 |
| Basement (40m²) | 40m² (430 sq ft) | £120,000-180,000 | £120,000-200,000 |
ROI: Extensions typically return 80-150% of investment in property value increase
For the cost of moving laterally (£37k-47k), you can build a quality 20m² single-storey extension that:
- Adds equivalent bedroom/living space without moving
- Increases property value by £40k-80k
- Keeps you in same location (schools, community, commute)
- No stamp duty, estate agent fees, or moving stress
Calculate your extension costs
Compare extension costs vs moving costs for your specific property.
Get Extension Estimate →When to Extend vs When to Move
Extend If:
- You love your location and neighborhood
- Children settled in local schools
- Need 1-2 extra rooms, not whole house upgrade
- Property has potential for value addition
- Want to avoid 2025 stamp duty increases
- Have garden space or scope for loft/side return
- Fixed mortgage rate ending soon (avoid remortgage)
Move If:
- Need to change location (work, family, schools)
- Fundamental property issues (damp, layout, structure)
- Need 3+ more bedrooms (extension too costly)
- No scope to extend (small plot, planning restrictions)
- Want fundamentally different property type
- Downsizing (release equity)
- Property already at maximum value for area
Hidden Factors: Beyond Just Money
Time & Stress
| Factor | Moving | Extending |
|---|---|---|
| Timeline | 3-6 months (search to completion) | 6-12 months (planning to finish) |
| Disruption | High - full house pack, move, unpack | Medium - live in house during build |
| Uncertainty | High - chain delays, fall-throughs | Low - controlled process |
| Emotional toll | Very high - leaving community | Moderate - construction noise |
Location Value
Your location may appreciate faster than you can upgrade via moving. If you're in a desirable London area (good schools, transport, amenities), extending lets you:
- Capture ongoing area appreciation
- Maximize property value in premium location
- Maintain access to best schools/amenities
Compare Extension Costs for Your Property
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Frequently Asked Questions
Is it cheaper to extend or move house in London?
For most London homeowners, extending is cheaper than moving. Stamp duty alone costs £21,650 on average London property (£543k). Add £15k-25k for estate agent fees, legal costs, and removals. Total moving costs: £36k-50k minimum. A quality 20m² extension costs £40k-60k but adds similar space without relocation stress or 2025 stamp duty increases.
How much is stamp duty in London 2025?
After April 2025 changes, stamp duty increased significantly. First-time buyer threshold dropped from £425k to £300k. Home mover threshold dropped from £250k to £125k. On average London property (£543k), stamp duty is £21,650. On £750k property: £32,500. On £1m property: £57,500. Additional 5% surcharge applies to second homes.
How much value does an extension add to a London property?
Extensions typically add 15-25% to property value in London. Single-storey rear extension (20m²): adds £40k-80k. Two-storey extension (40m²): adds £80k-140k. Side return: adds £35k-65k. Loft conversion: adds £40k-70k. ROI typically 80-150% depending on area and quality. Best ROI in high-value areas like Zones 1-3.
What are the hidden costs of moving house?
Moving costs beyond stamp duty: Estate agent fees (1-3% of value = £5k-16k on £543k), solicitor fees (£1,500-3,000), surveys (£400-1,500), removals (£800-2,000), EPC (£80-120), mortgage arrangement (£1,000-2,000), overlap rent/mortgage (£2k-5k), utility connections, redecoration. Total hidden costs: £15k-30k. Factor in disruption and stress.