Why Use the Extension Calculator?

Undertaking a home extension is a big task, and for many people, the cost will be a deciding factor. It's important to know how much value an extension will add to your home. This can help you make sure that adding your new kitchen, bedroom, or bathroom is worth it.

Knowing the value of an extension and how it will improve your property is important when you get a mortgage or loan to cover the extension costs. You'll want to ensure that the amount you're borrowing is covered by the additional value that it brings to your property.

If you're looking for an estimate on how much your extension will add, you can use this home extension calculator to help.

Once you’ve estimated how much value your extension will add to your house, read our guide to funding home improvements to get started on improving your home.

How Much Value Does an Extension Add?

It’s important to remember that the value an extension could add to your home will vary depending on a number of factors from the quality of construction, to the type of room - including whether it’s a kitchen extension or adding an extra bedroom - and the exact location of your property. This calculator provides an indication of how much you could add to your property by drawing on the average value of houses across local authority areas.

How Does the Value Calculator Work?

The house extension calculator below uses data from the Office of National Statistics, looking at property prices per square metre in England and Wales. It will indicate how much value an extension could add to your home.

Considering a home extension? Perhaps you want to extend your kitchen or bathroom or add an extra bedroom? Simply enter where you live and the size of the extension you’re looking to add and we’ll help you work out what an extension could add to the value of your home.

How Accurate Is It?

Our extension calculator is based on the size of your extension as well as where you live. There are, of course, other factors that will decide the exact value that an extension adds - such as how the extension may affect your garden or another area of the house, how the natural lighting will be affected etc. You should make sure you have considered these before starting your extension.

How Can I Pay for a Home Extension?

Our team can help look at what your options are for raising money from your home. We go through some potential ones below.

Further Advance

It may be that if you're doing smaller works you can get the finance from a further advance on your current mortgage deal. This lets you keep your current mortgage while accessing more funds. The further advance mortgage will often be at a different rate from your main mortgage.

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If you’re at the end of a fixed term mortgage you could remortgage to release some of the equity in your property. Compare remortgage deals with our free best buys tool. This can help get you the funds to build an extension on your home.

Second Charge Mortgage

Second charge mortgages, secured loans, or homeowner loans as they're sometimes known, are called second mortgages because they have secondary priority behind your main (or first-charge) mortgage.

They're a secured loan, which means they use the borrower’s home as security and are popular for those tied into their current mortgage who aim to repay the second charge via a remortgage when the main deal expires.

House Extension FAQs

How Do You Value a House Extension?

The most accurate way to find out the value that an extension brings to your property is to consult with a professional real estate agent. They can give you a valuation based on the exact details of the addition. Nonetheless, our house extension calculator can help you estimate the value that an extension will add to your home based on the size of the extension and the area you live in.

Do All House Extensions Add the Same Value?

No, there are many factors that will affect how much your extension adds to the value of your home. These include the type of extension and the location. Different areas have different property prices and different values per square foot and there can be a difference based on the exact location of a property. You'll also find that different additions, such as conservatories, bedrooms, or kitchen extensions, have different values.

How Do I Calculate the Cost of a House Extension?

The best way to calculate the cost of a house extension is to get a quote for the job from several reputable building firms. If you're looking at building the extension yourself, you can find an estimate for material costs per square metre for your extension. This will help you work out the rough cost, though you should always plan for additional expenses.

What Is the Best Way to Fund an Extension?

If you're unsure how best to fund your extension, our brokers can help you look at different mortgage options to find one that suits your needs. You could also look at loan options or self-funding your extension. To see how our expert brokers can help, get in touch now.