Self-build mortgage in the UK? It doesn't have to be difficult!

Do you dream of having your own home, but the properties you find on the classifieds portals don’t suit you? Think about building! Although it is a costly and risky venture, it can give you a higher standard of property and more opportunities to personalise your home. It all sounds lovely, but let’s deal with the finances first. In this article, we’ll explain to you how a self-build mortgage works and how to get one.

When will building pay off for you?

Building a house is a big financial commitment, and you need to bear in mind that you will encounter a number of costs that you would not incur when buying an existing property. These include:

• Purchase of a plot of land

• VAT on some materials and services, although you may be able to reclaim much of it through HMRC’s DIY Housebuilders Scheme if you claim within 6 months of completion

• Building design costs

• Planning application and building regulations fees

It should also be noted that many people opt for non-standard solutions, which can have a huge impact on the final cost of construction. For example, UK price guides put laminate flooring at around £22–£65 per square metre supplied and fitted, against around £60–£135 for engineered wood, so choosing wood across a large house can add several thousand pounds to the cost. Of course, it’s more pleasant to walk on parquet flooring, but be aware of the costs involved in installing it.

When might self-build be suitable?

• You own a plot of land or can buy it for a relatively small amount, for example at auction

• You can reduce labour costs by doing some of the work yourself

• You are able to wait to move

• You have savings for your deposit and unforeseen expenses

• You will get a mortgage for the construction with favourable conditions

• You are planning to build a fairly large house

• The properties available in your area would need expensive renovations to suit you

When might it be less suitable?

• You are not looking for customised solutions

• You are looking for a way to spend as little as possible on a house

• You are planning to build a small house, for example with two bedrooms

• You want to live close to the city centre

• You want to move quickly

• You do not have a large deposit

Why does the size and location of the house matter? One 2022 cost comparison suggested that, if you exclude the cost of land, building a larger home could cost less than buying a similar one. Also bear in mind that if you do manage to find a building plot in a city, it will be extremely expensive. Cities in the UK are very densely built up and local planning conditions are restrictive.

What conditions do you need to meet to get a self-build mortgage?

A self-build mortgage is riskier for the bank. During construction, literally anything can happen. For this reason, lenders make additional requirements to protect them from losing money. A self-build mortgage involves:

• Preparation of an architectural and structural design

• Obtaining planning permission and building regulations approval (in Scotland, a building warrant) before starting the construction work

• Release of funds in stages, either before each stage starts (advance) or after it is completed (arrears), depending on the product

• A deposit, the size of which depends on the lender and on whether funds are released in advance or in arrears

• Interest rates that can be higher than on a standard purchase mortgage

• The obligation to meet certain requirements of the bank. You will not be able to build a house in any way you like

• Enough income to pass the lender’s affordability checks. You have to live somewhere during the build, so the lender will take into account your current rent or mortgage payments.

Of course, there are more requirements and they vary depending on the bank you will use. As of the date of writing this article (26.04.2023), our company works with 28 lenders that can offer you a self-build mortgage and each of these companies has separate rules. For example, some lenders fund a higher share of each stage when funds are released in advance than when they are released in arrears.

By far the best option would be to use a broker, such as Extend Finance. Our staff will not only help you choose a favourable mortgage, but will also answer many questions about the formalities.

How much does it cost to build a house in the UK?

We wouldn’t be ourselves if there weren’t a lot of figures in this article. One 2022 estimate put the cost of building a 3-bedroom house in the UK at £240,000 to £360,000 and a 4-bedroom house at £290,000 to £440,000, excluding land; costs vary widely by size, specification and region and may have risen since. Let’s add a little more detail though.

The above figures do not include the cost of the plot, and it has a huge impact on the overall cost of the development. Land that already has planning permission for a home costs far more than land without it. One 2023 UK property guide estimated that an acre of land typically costs around £300,000 in the north and more than £1 million in the south, and prices vary widely by location and planning status.

A cheaper but riskier route is to buy land without planning permission, such as agricultural land. You can only build a home on it if the council grants planning permission, which is not guaranteed, so budget for the possibility that it is refused.

The next expense is planning permission. In England, the fee for a full planning application for a single new home is several hundred pounds (national fees are index-linked each April); fees differ in Wales, Scotland and Northern Ireland. The exact amount depends on a number of variables, so when calculating this it is worth using the guidance available on PlanningPortal. Also factor in design fees for an architect or designer, which vary widely with the size and complexity of the project. Of course, it all depends on your requirements and the specifics of the project, but if you want a unique look for your home, you need to expect to spend a lot on architect and builder work.

You probably also dream of a garden, which is not included in the standard cost of building a house. If you want your surroundings to be eye-catching, you will need to spend extra to realise it. Of course, you can take care of the garden later, which is reasonable anyway, and it is worth checking with your lender which costs the mortgage can cover.

Whatever deposit your lender requires, keep extra savings on top of it. After all, you need to bear in mind possible unforeseen problems, such as access to utility services, damage to windows during installation and inflation, which affects the cost of construction materials and the price of the construction team.

What can you do to build a house more cheaply?

For many people, saving a deposit and a financial buffer takes years, and you may need to move out within several months, which means incurring additional cost for rent. For this reason, it makes sense to look for ways to cut costs. For example:

• Consider whether you can do some of the work yourself. Of course, you will need a plumber or electrician with certain qualifications to do the installation, but you can learn many tasks, such as laying floors, at a surprisingly fast pace

• Look for construction workers among your friends. Perhaps someone could help you out in an exchange of favours?

• Avoid unusual and expensive finishing materials (exotic woods, marble) and consider what floor space you really need

• Ask your relatives to help you raise a deposit. Many lenders will not accept a deposit funded by other borrowing, but perhaps your parents have savings they could give you as a gift? Lenders that accept gifted deposits will usually want written confirmation, such as a gift letter or declaration, that the money is a gift and not a loan.

• Sell items you no longer need.

• Move to a smaller house or apartment for the duration of construction. A lower rent will increase your financial capacity

• Cut down on unnecessary expenses. Do you really need to go abroad on holiday?

• Depending on the lender and product, funds are released either before (in advance) or after (in arrears) each stage, and the lender funds a set percentage of each stage, with the rest coming from your own money.

Why does the deposit matter so much? The share of the costs a self-build lender will fund depends on the lender and product, while, as explained in the second part of the Q&A, many standard residential mortgages can finance up to 95% of the purchase price. This difference, of course, is due to different levels of risk, after all, during the erection of the house there is a much higher probability of problems. When the construction is over, it is possible to change the lender (to do a remortgage).

Once the build is complete, you may be able to remortgage to a standard residential mortgage, which may offer a lower rate. Any new mortgage, and any extra borrowing, depends on the lender’s affordability checks and valuation, may involve early repayment charges on your self-build product, and borrowing more increases the debt secured on your home.

Does a self-build mortgage carry a higher interest rate?

As you may have guessed, a self-build mortgage can be more expensive than a mortgage to buy an existing property. The interest rate on these products depends on your credit score and LTV (loan to value), among other factors. For example, Earl Shilton Building Society’s self-build mortgage showed a representative APRC of 7.1% when checked in September 2026.

As with other financial products, a self-build mortgage can come with both fixed and variable interest rates. This is, of course, our opinion and should not be taken as financial advice, but some borrowers choose a fixed rate for a period, planning to remortgage once the house is finished. Bear in mind that builds can overrun, and switching to a standard mortgage depends on the lender’s criteria at the time.

How long does it take to build a house in the UK?

When taking a self-build mortgage, you need to complete the stages within a certain period of time. After all, in addition to the bank’s requirements, the rent you pay while you build and the interest on your mortgage also add up. Build times vary widely with the size and complexity of the project, the weather and the availability of trades and materials, so allow for delays in both your budget and your timetable.

Summary

Perhaps our article has dissuaded you a little from building your own home and applying for self-build mortgage. It is an expensive venture, but if you decide with the right amount of cash, it is definitely worth considering. The ability to tailor the property to your and your family’s needs repays itself in much greater comfort, and a well-built home can serve you for many years to come.

Looking to build or buy a property in the UK? Make an appointment for a free, no-obligation consultation with our experts. We can help compare the mortgage options available to us, taking account of costs and your circumstances. Approval and terms depend on the lender.

Are you interested in real estate? Check also:

• What to ask a mortgage advisor?

• How to buy a house in the UK?

• Property prices in the UK