Extend or Move? Why London Homeowners Are Choosing to Stay and Build in 2026

For London homeowners asking "should we extend or move?", the financial answer is increasingly clear: staying and building often makes more sense than moving. With house prices still 5% below their 2022 peak, stamp duty at its highest in years, and estate agent fees eating 1.8% of your sale price, the transaction costs of relocating have never been steeper. Meanwhile, a well-planned extension can deliver 15–20% value gain without the bureaucracy, disruption, or financial drain of moving.

This April, we're breaking down the real numbers: what moving actually costs, why extending delivers better ROI, and how 2026's market conditions make the extension decision a smart financial move for many London families.

The True Cost of Moving in London: Beyond the Headlines

Most London homeowners know that moving is expensive. But few realise just how expensive until they start adding up the costs. Let's walk through the real figures for 2026.

Notice what's happening here: before you've even finished packing, before you've negotiated a single brick with the new owner, you've committed to spending nearly £25,000 just to facilitate the move.[1][2]

The Stamp Duty Shock of April 2025

The biggest culprit in moving costs? Stamp Duty Land Tax (SDLT). From April 1, 2025, the UK government rolled back temporary stamp duty cuts, and the nil-rate threshold for home movers fell sharply.

• Old rates (pre-April 2025): No stamp duty on first £250,000
• New rates (April 2025 onwards): No stamp duty on first £125,000 only

On a £400,000 London property—hardly exceptional in the capital—this change means £5,000 more in stamp duty costs. On a £500,000 property, you're paying roughly £10,000. On a £600,000 property in prime areas like Islington or Wandsworth, you're looking at £13,000.[3]

Add to this the fact that 14.8% of Londoners who sold in 2025 sold for less than they bought the property for, and you see why transaction costs now represent an even larger percentage of remaining equity for many homeowners.

Why London House Prices Matter Right Now

London's property market in 2026 presents a unique paradox: prices have recovered partially from their pandemic lows, yet they remain stubbornly below the 2022 peak. This has profound implications for the extend-or-move decision.

What does this mean for your decision? If you're planning to upsize, you're not just paying transaction costs—you're potentially buying into a market that hasn't recovered. London is the only UK region where prices sit below 2022 levels.[4][5]

Conversely, if you like your current home and neighbourhood, there's a compelling financial case to stay and extend.

The Extension Advantage: Real Numbers

Now let's look at the alternative: extending your existing home. The costs are substantial, but the structure is fundamentally different—every pound spent is adding value to a property you already own, in a neighbourhood you've already chosen.

Extension Costs in London 2026

The cost per square metre for extensions varies by type and location, but here's what you're looking at:[6]

• Single-storey rear extension: £2,500–£4,000 per m²
• Two-storey extension: £5,500–£7,500 per m²
• Loft conversion (dormer): £2,500–£3,500 per m²

Professional fees (architect, structural engineer, building control) add 10–15% on top of construction costs.

At first glance, £91,000 seems like a lot—and it is. But here's where the financial case becomes compelling: that extension doesn't just cost money; it creates value.

Return on Investment: Extensions vs Moving

The critical difference between spending £91,000 on an extension and spending £25,000 on moving costs is that the extension adds value to your property, while moving costs are pure transaction expense that evaporates the moment you complete on the sale.

What Extensions Add to Property Value

Research from London property specialists shows:[7]

• Single-storey extensions: Add 15–20% to property value
• Two-storey extensions: Add 15–20% to property value
• Kitchen open-plan extensions: Add 10–15% to property value
• Loft conversions: Add 20–25% in inner London, 15–18% in outer London

Let's take a concrete example: you own a £600,000 terraced house in Hackney. You add a £75,000 dormer loft conversion.

Expected value increase: £120,000 (20% gain)

Your return on investment: 60% of the conversion cost is immediately recovered in added property value. Even accounting for future market fluctuations, you've made a smart financial investment while staying in a home you love.

Why Extending Makes Financial Sense

Let's compare two scenarios for a London homeowner with £600,000 in property equity:

Scenario A: Move to a larger property

• Sell current home: £600,000
• Less moving costs: –£28,000
• Equity available for new property: £572,000
• New property cost: £750,000
• Additional mortgage required: £178,000
• Your outcome: Larger home, £178k additional debt, £28k in non-recovered costs

Scenario B: Extend current home

• Extension cost: £91,000
• Value added: £120,000+
• Net position: Same location, enlarged home, £29,000 net equity gain, minimal disruption

In Scenario B, you've achieved more space, added equity, and kept your existing community—without taking on new mortgage debt or paying massive transaction fees.

The Market Context: 2026 Makes Extending More Attractive

Several factors in the 2026 London market make extending particularly attractive right now:

1. Price Uncertainty Remains

With London prices still 5% below their 2022 peak, the idea of "buying low" might seem appealing. But the reality is murkier. Savills predicts London house prices will flatline in 2026 and only resume growth from 2027. This suggests that moving to upsize now means paying for a market that may not appreciate significantly in the near term.[8]

2. Rising Stamp Duty Penalises Movers

The April 2025 stamp duty changes specifically penalise moving. Every £50,000 increase in purchase price now costs £1,000 more in stamp duty than it did previously. If you're already hesitating about moving, stamp duty has just become a stronger argument for staying.

3. Extension Financing is More Flexible

While moving often requires a full new mortgage, extensions can be financed through:

• Home improvement loans (often with lower rates than mortgages)
• Remortgaging (using equity to release cash at better rates)
• Savings and smaller personal loans
• Combination of the above

This flexibility means you can spread costs and avoid the fixed transaction timeline and stress of the moving process.

When Should You Still Move?

The financial case for extending is strong, but it's not universal. You should consider moving if:

• You need significantly more space. If you're adding a second bathroom and bedroom permanently, extensions are great. If you need a complete different floorplan or dramatically more square footage, a new property might be right.
• You want a different location. Extending keeps you in the same neighbourhood. If you need to move for work, schools, or lifestyle, extending doesn't solve that.
• Structural issues exist. Some older London properties have fundamental issues—subsidence, poor foundations, impossible extensions due to listed status. In these cases, moving saves future headaches.
• You've outgrown the area entirely. If your neighbourhood no longer meets your needs, moving offers a fresh start that extending cannot.

But for many London homeowners simply looking for "a bit more space" or "a better kitchen"? The extension case is financially overwhelming.

Estate Agents and Renewal: The Ongoing Cost of Moving

One final consideration: the estate agent fee structure in London is worth examining. The average estate agent in London charges 1.5% plus VAT (1.8% including VAT) for sole agency on a property sale.[9]

On a £500,000 property, that's £9,000. On a £750,000 property, it's £13,500.

These fees exist regardless of whether the market moves in your favour. Even if you sell quickly, you pay full commission. If the market slows and your property takes longer to sell, you may negotiate, but most London agents are well-protected by contract terms.

Extensions, by contrast, are a one-time investment with permanent value.

Making Your Decision: The Extension-or-Move Framework

Here's a simple framework to help you decide:

1. Do you like your home and neighbourhood? If yes, extending is almost always better financially. If no, moving might be right despite the costs.
2. Can an extension solve your space problem? Extensions work for kitchens, bathrooms, bedrooms, and living space. They don't work for fundamentally wrong locations or floorplans.
3. What would moving actually cost you? Calculate your specific stamp duty (use a calculator for your exact price), get three agent quotes, and factor in legal and survey costs. Many homeowners are shocked by the total.
4. What would an extension add to your property value? Talk to local builders and architects. A 25 m² extension typically adds £100k–150k in value across most of London.
5. Is the extension ROI positive? If the value added exceeds the extension cost by 20–30%+, you're making a smart financial move.

The Bottom Line for London in 2026

London homeowners asking "extend or move?" are facing unprecedented financial pressure around moving. Stamp duty is at its highest point in years. Estate agent fees are fixed and substantial. The property market is flat. And the cost of your transaction—not your new property—is often the biggest financial drag.

Meanwhile, extensions deliver immediate value, avoid transaction costs, and let you stay in homes and neighbourhoods you love.

For most London families, the financial case is clear: stay and build.

Frequently Asked Questions