Bridging finance for loft conversions

Turning roof space into value - and funding it right

Rising build prices have not dampened demand for extra space. Across the UK, loft conversions typically range from £40,000 to £50,000 for a standard dormer in 2025, with basic Velux models at the lower end and mansards at the premium end. London is a different league. Capital projects commonly fall between £50,000 and £90,000 for many designs, with dormers often starting around £70,000 and complex L-shaped or mansard layouts reaching six figures. These premiums reflect tighter sites, access challenges and specification expectations.

That context matters for finance. Renovation costs arrive upfront, while the uplift in property value tends to crystallise only at completion, refinance or sale. Many households sit on paper equity they cannot immediately access, yet contractors need deposits now and materials are paid on order. A short-term bridging loan can close this timing gap so the build proceeds on schedule.

The build itself is typically swift compared to ground-up extensions. A Velux conversion can complete in four to six weeks, dormers in six to twelve, and hip-to-gable in eight to ten. Faster schedules mean interest on short-term finance accrues over fewer months, which helps overall affordability. For properties with sufficient head height, a Velux conversion remains the most cost-effective route, often around £27,500 for 30 m², whereas dormers of the same footprint average near £50,000. Where maximum space is essential, mansards can run from £60,000 UK-wide to well above £100,000 in London.

The key is aligning the loan term and exit plan with a realistic build timetable and expected value uplift.

Well-planned projects commonly add 20 to 25 percent to a property’s value, with London and the South East seeing strong returns thanks to high price per square metre. Regional spreads matter too. Many homes in the North of England fall into the £30,000 to £60,000 range, with Wales and Scotland slightly below some English regions. Understanding these bands helps you budget accurately, control risk and choose the right finance to bridge the gap between now and completion.

Who benefits from short-term funding solutions

Bridging finance suits homeowners who need to start quickly, have strong equity, and a clear exit such as sale or remortgage after completion. It also helps buyers completing a purchase who intend to convert immediately to unlock extra bedrooms or a home office. Households in London and the South East often use bridging to fund higher upfront costs, while owners in more affordable regions may use it to press ahead without waiting for savings to accumulate. If your contractor requires staged deposits and you prefer not to remortgage mid-rate or incur early repayment charges, short-term funding can be a practical, targeted tool.

Your loft options and typical ranges

1. Velux conversion - from roughly £22,500 to £30,000 for 30 m² - fast 4 to 6 weeks.

2. Dormer conversion - commonly £35,000 to £60,000 for 30 to 50 m² - 6 to 12 weeks.

3. Hip-to-gable - often £45,000 to £70,000 - 8 to 10 weeks.

4. Mansard conversion - usually £60,000 to £85,000+ UK-wide, up to £150,000 in London.

5. Shell-only conversion - from about £37,500 for 30 m² - finish in phases.

6. London premium - many projects £50,000 to £90,000, with complex designs higher.

Cost, timing, return and risk snapshot

Can you qualify - and on what terms

Lenders assess the property value, existing mortgage, and projected end value post-conversion. Expect checks on available equity, your credit profile, and the contractor’s programme. The cornerstone is your exit strategy - typically a remortgage onto a standard product once works complete, or a sale to repay the bridge. Planning requirements must be satisfied where applicable, and permitted development must be evidenced if you rely on it. Clear, itemised costings with a contingency give lenders confidence that timelines and budgets are realistic. If the property is in London or the South East, assume stronger scrutiny of costs and timelines given higher averages. Kandoo can introduce you to a panel of UK lenders offering bridging options suited to different project sizes, with terms that reflect regional variations in price and demand.

From application to completion - the key steps

1. Get a ballpark budget and confirm your loft type.

2. Request quotes and a timeline from reputable contractors.

3. Secure planning or confirm permitted development status.

4. Apply for bridging with evidence of exit plan.

5. Valuation and legals progress in parallel to underwriting.

6. Funds drawdown - pay deposits and order materials.

7. Works complete - snagging and final building control sign-off.

8. Remortgage or sell to repay the bridge.

Bridging benefits and trade-offs at a glance

What to weigh up before you commit

Your budget should accommodate realistic quotes plus a contingency for price movements or structural surprises. Ensure your chosen design suits the roof form and head height so you do not overpay for space you cannot use. Planning consent may be needed for mansards or street-facing dormers, and neighbours might be party wall stakeholders. Insurance, building control approvals and contractor due diligence are non-negotiable. In London, allow for access restrictions that can lengthen timelines and deliveries. Your exit plan must be credible - if refinancing, check loan-to-value and affordability against the projected end valuation. If selling, account for market time to complete the chain.

Alternatives if bridging is not the fit

1. Remortgage to release equity once early repayment charges end.

2. Further advance from your current lender on your existing mortgage.

3. Unsecured home improvement loan for smaller Velux or shell works.

4. Savings plus phased shell-first, finishes-later approach.

5. Developer or contractor stage-payment plans with retention.

6. Part-sell investments to reduce borrowing requirement.

Frequently asked questions

Q: How much does a typical loft conversion cost in 2025? A: Many UK dormers sit around £40,000 to £50,000, with Velux options near £27,500 for 30 m² and mansards from £60,000 upwards. London projects often start higher and can exceed £100,000.

Q: How long do loft works usually take? A: Velux builds often finish in four to six weeks, dormers in six to twelve, and hip-to-gable in eight to ten. Complex designs can take longer, especially in urban areas.

Q: When does bridging finance make sense? A: When you have equity, need to start quickly, and have a clear exit like remortgage or sale. It can prevent delays while materials and contractors are available.

Q: What deposit or equity do I need? A: Requirements vary by lender, but strong equity and a comfortable loan-to-value on day one and on exit are important. A realistic budget and contingency also help.

Q: Will a loft conversion increase my property value? A: Many projects add 20 to 25 percent, particularly in high-demand areas such as London and the South East. Exact uplift depends on design quality and local market conditions.

Q: Can I finance a shell now and finish later? A: Yes. Some borrowers fund a shell conversion first, then complete interiors later. Bridging can support phased works where the exit plan accounts for the staged timeline.

Next steps to move forward

• Gather quotes and drawings for your preferred loft type.

• Check planning or permitted development requirements.

• Estimate end value and your exit plan options.

• Speak to Kandoo to compare bridging offers.

How Kandoo helps you move faster

Kandoo is a UK-based retail finance broker that can introduce you to a wide panel of bridging lenders. We help you compare rates, fees and terms, align drawdowns with your build schedule, and structure a credible exit plan so you can start with confidence and finish on time.

Important information

Bridging loans are secured and may put your property at risk if you do not keep up repayments. Costs and timelines vary by region and project complexity. Always seek independent financial advice and verify planning, legal and tax implications before proceeding.