Buy or Improve in London: When to Renovate Your Existing Home vs Moving to a Bigger Property

Moving property in London is expensive — significantly more expensive than most homeowners calculate when they first consider moving. The total transaction costs of selling and buying in London typically amount to 5 to 10% of the property value. For a family moving from a £700,000 terrace to a £1,000,000 property, the transaction costs alone can exceed £60,000:

Costs of selling:

• Estate agent fees: 1 to 2% of sale price plus VAT (£8,400 to £16,800 on a £700,000 sale)
• Conveyancing (selling): £1,000 to £2,000 plus disbursements
• Energy Performance Certificate: £60 to £120

Costs of buying:

• Stamp Duty Land Tax (SDLT): on a £1,000,000 property, SDLT is currently £43,750 for a standard purchase (2025 rates, having returned to pre-2022 thresholds). If the buyer retains the existing property (buy to let), the additional 3% SDLT surcharge would apply
• Conveyancing (buying): £1,500 to £3,000 plus disbursements
• Survey (RICS Level 2 or 3): £500 to £1,500
• Mortgage arrangement fees: £0 to £2,000 depending on product
• Removal costs: £1,000 to £5,000 depending on property size and distance

Total transaction cost on a typical London move (selling £700K, buying £1M): approximately £55,000 to £75,000 in unavoidable transaction costs, before any immediate works on the new property.

This transaction cost burden must be weighed against the cost of improving the existing home.

Improving an existing home typically:

• Is disrupting during construction (may require temporary relocation, living on a building site for 3 to 12 months)
• Delivers exactly the improvements prioritised (you choose what to change)
• Does not deliver location, neighbours, schools catchment, or other contextual factors you cannot change
• Has lower transaction costs than moving
• Usually takes 6 to 18 months from decision to completion
• Adds equity value in addition to lifestyle value

Moving to a larger or better property typically:

• Delivers an immediate improvement (move in to a finished property)
• Allows location change (different school catchment, closer to parks, transport links)
• Is subject to the availability of suitable properties in the target area at the right time
• Involves all the transaction costs above
• May require further renovation work in the new property
• Provides certainty about the outcome (you can see what you are buying)

Are the constraints of your current home location-dependent or property-dependent?

If you want more space and your current location meets your needs (schools, work commute, social connections, neighbourhood quality), improving is likely the better financial decision. If the limitations are location-dependent (catchment area for a preferred secondary school, distance to family, need to change commute), then moving may be the only solution.

Is your current property structurally capable of delivering what you need?

Not all London homes can provide every improvement. A flat on an upper floor cannot have a rear extension. A one-bedroom period flat cannot typically provide a third bedroom without compromising all other rooms. A terraced property with limited width cannot deliver an open-plan ground floor if structural walls constrain the plan. If the structural envelope cannot deliver what you need, improving is not an option.

What is the ceiling value in your street?

Every street and micro-market in London has an effective price ceiling — a point beyond which even the best-renovated property will not sell above comparable unrenovated properties by more than approximately 20 to 25%. If your property value is already at or near the street ceiling, investment in renovation will not be recovered on sale. If there is significant headroom below the ceiling (your property is below-average for the street due to its condition), renovation can recover cost and more.

How long do you intend to stay?

If you plan to stay for 10 or more years, the financial return on renovation matters less than the lifestyle improvement, and the transaction cost calculation favours improving strongly. If you are likely to move within 3 to 5 years, the transaction costs of moving are significant but so is the risk that renovation costs are not recovered on a relatively quick sale.

Consider a family in a London 3-bed terrace worth £700,000, considering either:

• Extending to create a kitchen-diner and a 4th bedroom (cost: approximately £120,000)
• Moving to a 4-bed terrace in the same area at £900,000

Option 1: Improve

• Cost: £120,000 (extension and refurbishment)
• Disruption: 4 to 8 months of construction
• Estimated value after completion: £800,000 to £830,000 (adding more than construction cost in a strong market)
• Remain in same location, same neighbours, same community

Option 2: Move

• Transaction costs: approximately £50,000 to £65,000
• New mortgage: approximately £700,000 borrowing (assuming £200,000 equity from sale plus top-up)
• Immediate: move into the new property (no construction disruption, but packing, moving, settling)
• May still need to improve the new property (kitchen, bathrooms, etc.)
• Total cost over 2 to 3 years including transaction costs and any improvement works at new property: potentially £80,000 to £150,000 or more

In this example, improving is almost always the better financial decision when the homeowner intends to stay for more than 5 years and the property is structurally capable of delivering the required improvements.

Moving wins when:

• Location change is required (school catchment, commute, family proximity)
• The structural envelope genuinely cannot deliver the required improvement
• The property is already at or near the street value ceiling
• The household needs immediate improvement without living through construction
• The move captures a specific opportunity (property at below-market value, inheritance-enabled upsizing) not available through renovation

For London homeowners: if you like your area, can achieve the improvements you need within your property, and plan to stay for 5 or more years, the mathematics of improving almost always beats moving. The transaction cost of moving in London is a very high hurdle that renovation must overcome — and for most families, it does.

Engage a RICS-registered surveyor to assess the realistic post-renovation value of your improved home before making the decision. Their valuation advice, combined with contractor quotes for the works, provides the objective financial framework to make the decision confidently.