A full renovation of a three-bedroom house in the UK now runs anywhere from £60,000 to £200,000, and extension-led projects regularly push past £250,000. These aren’t numbers you can pull from a savings account and forget about. At this level, the funding decision becomes a financial planning question in its own right, and getting it wrong can set you back for years.
On the other hand, renovating instead of moving will save you tens of thousands in stamp duty, estate agent fees and legal costs, so it can make strong financial sense if the funding is structured properly.
The tricky part is that most homeowners don’t think about funding until they’ve already fallen in love with an architect’s drawings. By then, the emotional momentum makes it harder to step back and weigh up the options clearly. Here’s what those options actually look like, and where the money quietly disappears.
Remortgaging vs. a Further Advance
If you’ve built up equity in your home, remortgaging is usually the first option on the table. You’ll replace your current mortgage with a larger one, releasing the difference as cash. Rates will depend on your loan-to-value ratio, and you’ll need to factor in arrangement fees, valuation costs, and any early repayment charges on your existing deal.
A further advance is the alternative. Your current lender offers you additional borrowing on top of your existing mortgage, often at a different rate. It’s quicker than a full remortgage and avoids the cost of switching, but you won’t always get the best rate this way.
Either route ties the renovation debt to your home over 20 or 25 years. That’s cheap monthly payments, but a lot of interest over the full term. Run the total cost, not just the monthly figure.
Personal Loans and Bridging Finance
For smaller renovations, or to cover a gap in funding, an unsecured personal loan can work. You’ll pay higher interest than a mortgage, but the debt is typically cleared in one to seven years and your home isn’t used as security.
Bridging finance is another option if timing is tight, say you’re buying a property to renovate before selling your current one. It’s expensive and short-term by design, so it only makes sense when you have a clear exit strategy.
Draw Down Savings or Stay Invested?
This is where things get interesting. If you’ve got £150,000 across savings and investments, it might seem obvious to just use it and avoid paying interest altogether. But where that money sits matters. Withdrawals from an ISA are completely tax-free, no matter the amount. Investments held outside an ISA are a different story.
The capital gains tax annual exempt amount is now just £3,000 per person, and rates sit at 18% for basic-rate taxpayers or 24% for higher-rate taxpayers. Liquidating a large chunk of a general investment account could trigger a significant tax bill on top of losing the compound growth on that money.
If you’re sitting on a large portfolio, private wealth management can model exactly this kind of scenario, mapping out how a big drawdown will affect your tax position, retirement timeline and long-term goals before you commit to a number.
The answer isn’t always one or the other. A mix of partial drawdown and borrowing can sometimes protect your long-term position while still keeping interest costs manageable.
The Hidden Costs That Blow Renovation Budgets
Funding the build is one thing. Funding the overruns is another. Late specification changes are the biggest culprit.
Changing your mind on a kitchen layout after the plumber has already done the first fix, or swapping tile suppliers halfway through, is one of the main drivers. Industry data suggests most UK renovations end up 15-25% over budget, driven by a combination of late spec changes, unforeseen structural problems, and scope that was never properly pinned down before the contract was signed. Every variation has a ripple effect on trades, timelines and materials.
Other costs that catch people out:
- Temporary accommodation if you can’t live in the property during works
- VAT on labour and materials (a full 20% that’s easy to forget when quoting net prices). One exception: if the property has been empty for two or more years, renovation work may qualify for a reduced 5% VAT rate. And until March 2027, energy-saving installations like insulation, solar panels and heat pumps are zero-rated.
- Professional fees for architects, structural engineers, and building control
- Furnishing a newly finished space, which can easily add another £10,000-£30,000
Build a contingency of at least 15% into your budget from day one. If you don’t use it, great.
The Emotional Pressure to Overspend
Living in a building site does something to your decision-making. After weeks of dust, noise, and cold showers, the temptation to say “just do it” when your contractor suggests an upgrade is real. That’s how a £120,000 project quietly becomes a £160,000 one.
Set your budget before work starts and agree with your partner or family on a decision-making process for changes. If anything over £500 needs a 24-hour cooling-off period, you’ll avoid most impulse upgrades.
A Renovation Your Finances Can Actually Support
The best-funded renovations aren’t necessarily the cheapest ones. They’re the ones where the homeowner understood the full picture before breaking ground: what the project will cost, how the funding fits into their wider financial life, and where the pressure points will be. Get that right, and you’ll end up with a home you love and a financial position you can still live with.
Risk warning: The value of any investment can fall as well as rise, and the same applies to the income it produces. Getting back less than you invested is a real possibility. Past performance is not a dependable guide to future performance.