How to Remortgage for a House Extension in the UK?

Many UK homeowners are choosing to improve rather than move—and one of the most popular questions we hear is: Can I remortgageRefinancing an existing mortgage with a new mortgage. to build an extension? Whether you’re dreaming of a single-storey rear extension, a loft conversion, or even a basement conversion, remortgaging can be a viable financing option. In this guide, we’ll cover what you need to know, from your current mortgage deal to equityThe difference between the value of the property and the amo... release, monthly repayments, and how mortgage lenders assess your financial situation.

The article is updated as of April 22, 2025

Your home may be repossessed if you do not keep up repayments on your mortgage.

Always consider the total cost of borrowing before committing to a new mortgage deal.

What Does Remortgaging Mean?

Understanding the Basics in Simple Terms

Remortgaging means switching your current mortgage loan to a new one—usually to get cheaper mortgage rates, borrow extra money, or both. You might stay with your current mortgage provider or switch to a different lender altogether. Sometimes, homeowners take out a separate mortgage or even a secured charge loan depending on their borrowing limits and credit score.

How Property Equity Plays a Role

Your home’s equity—the difference between its current market value and your outstanding mortgage balance—is key to how much additional borrowingWhat is Additional Borrowing? A Quick Overview When you take... is possible. Releasing equity is a common method of raising funds for a house extension or comprehensive extension project. According to NeedingAdvice.co.uk, lenders usually expect you to have sufficient equity before approving your remortgage application.

Why Remortgage to Build an Extension?

Extensions not only create extra living space, but they also add value to your current property. Whether you’re adding an additional bedroom, turning attic space into an office, or investing in solar panelsThe presence of solar panels on a property that may affect t... as part of a wider renovation project, it can be a smarter move than relocating—especially given high property prices and cost for building materials.

Common Types of Extensions

• Loft conversions for that bit of space under the roof
• Single-storey extension at the rear or side of the house
• Multi-storey extension for larger families
• Basement conversion for homes with limited outside space

Advantages of Staying Put

Working with your current mortgage lender or a mortgage broker with access to the entire market might help you find a cheaper option than moving home. According to the Mortgage Advice Bureau, extending your home often works out better than paying stamp dutyA tax paid by the buyer when purchasing a property., legal fees, and estate agent costs associated with moving.

What Do Lenders Consider Before Approving?

Eligibility Criteria for Remortgaging

• Your credit score and credit rating, including any history of adverse credit or a bad credit history
• Current income, annual household income, and overall financial situation
• Current mortgage balance and your existing mortgage interest rate
• Whether your type of mortgage (e.g., fixed-rate mortgage, buy-to-let mortgage) allows for additional borrowing
• Availability of detailed plans, official quotes, and accurate cost estimates for the building project

Credit Issues to Watch

If you’ve had a bad credit score or past credit issues, specialist lenders may still offer secured loans or Refurbishment mortgages. Your attitude to debt and overall current debt will be assessed too.

Cost Considerations

Lenders also expect an estimate of the cost of extension including decorating costs, cost of labour, and the actual cost of materials. The total cost of borrowing will depend on your repayment plan and loan terms.

Pros and Cons of Remortgaging for Home Improvements

Why It Could Be the Cheapest Option

• Access to cheaper rates than unsecured loans or credit cards
• Ability to spread monthly mortgage payments over a longer mortgage term
• Potential to increase the value of a detached or semi-detached house significantly

Downsides to Consider

• Paying more interest over a longer period of time
• Possible early repayment charges on your current mortgage agreement
• Complex remortgaging process and application process with credit checkA check of a borrower's credit history, which is used by mor... and paperwork like current mortgage statements

Cost Comparison: Remortgaging vs Unsecured LoansCan I Remortgage to Build an Extension?

Building an extension—whether a loft conversion, rear extension, or double-storey upgrade—is an increasingly popular choice for homeowners looking to improve rather than move. But with building costs rising and savings stretched thin, many ask: Can I remortgage to build an extension?

According to NeedingAdvice.co.uk, remortgaging to fund an extension is not only possible, but often the most cost-effective way to release equity for a major renovation project. Whether you’re early in your mortgage term or nearing the end of a fixed-rate mortgage, the key is understanding your current mortgage deal, financial position, and the expectations of mortgage lenders.

How Remortgaging Works for Extensions

Releasing Equity from Your Home

If your home has increased in value since you bought it—or if you’ve paid down a chunk of your loan—you may have sufficient equity to tap into. This process, often referred to as equity release or additional borrowing, lets you raise extra money for an extension project without taking on an entirely new separate mortgage.

Equity release through remortgaging tends to offer cheaper rates than unsecured loans or credit cards. Just remember: the larger the amount you borrow, the higher your monthly mortgage payments—so make sure the extra borrowing fits your financial situation.

What Types of Extensions Can Be Funded?

• Loft conversions to create a new double bedroom or home office
• Single-storey extensions for larger kitchens or living areas
• Multi-storey extensions for families needing serious space
• Basement conversions and solar panels as part of a green improvement project

What Mortgage Lenders Will Consider

Affordability and Eligibility

Before approving your remortgage application, lenders will check your credit score, credit rating, and any history of adverse credit. If you’ve got a bad credit score or past credit issues, your options may be limited—but specialist lenders or Mortgage brokers with access to the entire market can often still help.

Planning Permission and Detailed Plans

As NeedingAdvice.co.uk explains, if your extension costs exceed a certain level or the design changes the structure significantly, you may need planning permissionPermission granted by the local authority for a property to .... Even where this isn’t needed—under permitted development rights—you’ll usually be expected to provide:

• Detailed plans of your dream extension project
• Official quotes for the cost of extension
• Accurate cost estimates from builders and suppliers

Property Type and Value

Lenders will look at your property type—e.g., detached or semi-detached house—and compare it to current market values in your area. An estate agent or valuer may be required to assess the likely post-renovation value, which can affect your borrowing capacity.

Costs and Financial Planning

Understanding the Total Cost

Your lender—and your own budget—will need to reflect the total cost of building your extension. This includes:

• Cost for building materials and cost of labour
• Decorating costs and final finishes
• Any additional costs like architecture fees or inspections
• Backup for a potential actual cost overrun

According to Household Quotes, the average cost of a modest UK house extension starts around £1,500–£2,500 per square metre, but this can rise depending on materials, location, and design.

Comparing Finance Options

If remortgaging doesn’t suit your situation, there are alternative options:

• Further advanceAdditional borrowing secured against a property that already... from your current lender
• Secured charge loan or second charge mortgage
• Unsecured loans for smaller extensions or cosmetic work
• Support from a credit union or cash funds from savings
• Equity loan or equity release for over-55s

Each financing option comes with its own repayment terms and risks. It’s essential to get advice from an independent mortgage broker or the expert team at NeedingAdvice.co.uk before proceeding.

Making an Informed Decision

Whether you’re on your original mortgage or nearing the end of your current mortgage agreement, it’s important to:

• Review your current mortgage terms and current deal
• Understand the potential increase in mortgage repayments
• Speak to an experienced mortgage advisor before committing
• Consider any fee for mortgage advice and whether it’s worth the insight

With careful planning, you can use your home’s equity to unlock a beautiful dream project. Whether it’s an extra bit of space for the kids, a new kitchen-diner, or that long-awaited comprehensive guide to a development project, the right remortgage deal can bring your vision to life.

Need Help Navigating the Remortgaging Process?

The team at NeedingAdvice.co.uk offers a complete guide to the remortgaging process, with mortgage recommendations tailored to your goals and credit profile. Whether you’re dealing with bad credit borrowers, navigating negative equityA situation where the value of the property is less than the..., or simply looking for the cheapest money available, they can help you explore every possible route.

Final Thoughts: Is Remortgaging Right for Your Extension?

Remortgaging to fund a house extension can be a smart move—but only if it suits your attitude to debt, current income, and long-term plans. With the right broker with access to a wide range of mortgage products—and a firm grasp of your actual cost estimates—you can make a confident, informed decision that enhances your home and your life.Alternatives to Remortgaging

Remortgaging isn’t your only route. Depending on your borrowing capacity and type of house extension, here are a few alternative options:

• Further advance from your current mortgage provider
• Secured loans as a second charge on the home
• Equity loan or equity release for older homeowners
• Unsecured loans for smaller projects with good credit card limit
• Credit union borrowing for those with limited options
• Cash advance from personal savings or low-interest promotions
• Government-backed financing option for green improvements

Expert Advice and Resources

A mortgage broker or independent mortgage broker with access to specialist mortgage products and the entire market can help you explore all your remortgage options. If you’re facing adverse credit history or need recommendations with access to niche lenders, speak to an experienced mortgage advisor with a dedicated finance team.

The expert team at NeedingAdvice.co.uk offers guidance on how to prepare your initial mortgage documents, get an accurate quote, and understand what to expect from your remortgage deal.

Other Resources

• Remortgage Guide – NeedingAdvice.co.uk
• Household Quotes – Compare Extension Costs
• Nuts About Money – UK Financial Guidance
• Mortgage Network Limited

Can I Remortgage to Build an Extension? – Final Thoughts

With careful planning and the right advice, remortgaging to fund a dream extension project can be one of the most effective ways to create additional space in your home. Whether you’re looking to add a double bedroom, maximise your attic space, or future-proof your home with a rear extension, take the time to understand your options, get accurate cost estimates, and make an informed decision.

Speak to a broker with access to the full market, compare deals from building societies and specialist lenders, and make sure your current deal still fits your long-term goals. When done right, remortgaging can be the smartest way to turn your current home into your forever home.