Self-build Mortgages Explained

A self-build mortgage is a type of loan designed to help finance the cost of building your own home. By paying out the funds in stages, self-build mortgages aim to make sure your money won’t run out before the build is completed.

Jim Kersey, Tim Leonard Published on 10 December 2019. Last updated on 22 October 2021.
Self-build Mortgages Explained

Building your own property can deliver the home of your dreams, but how you finance a self-build can be crucial to getting the job done. You might have savings or an existing home to sell, but for many a self-build mortgage will be required to bring their property off the drawing board and into reality.

What is a self-build mortgage?

A self-build mortgage is a home loan designed to finance the purchase of a plot of land and the cost of the building works for constructing a home in which you live on that land. Whether you’ll be doing most of the building work yourself, or intend to use a specialist contractor, a residential mortgage – which is designed to finance the purchase of property that is already standing – is not suitable for funding the construction of a self-build home.

Unless you have a lump sum set aside to fund your building work outright, it’s likely you’ll need to secure a self-build mortgage to help finance your build. This type of mortgage is designed to consider the differences and additional risks involved with the task at hand.

While the funds provided by a residential mortgage are released as a single lump sum, the monies delivered by a self-build mortgage are paid in instalments to help ensure that projects are continually funded as they progress.

As an example, a portion of the overall sum you borrow through a self-build mortgage could be released on completion of each of the following stages:

  • buying the land
  • putting in the footings and foundations
  • erecting the walls
  • adding the roof
  • installing fixtures and fittings, and completion

By releasing the funds gradually, the aim is to help lower the risk posed to both borrower and lender that the money lent through a self-build loan will run out before the house is completed.

The different types of self-build mortgage

Self-build mortgages typically take one of two forms, and will depend on when a lender is willing to release each tranche of funds.

An arrears mortgage

Most self-build mortgages tend to pay out in arrears, releasing the relevant amount of funds upon the completion of each designated stage of the build. Usually, a valuation expert sent by the mortgage lender visits the build site to check that the particular section of work has been completed as agreed, and to authorise the release of the funds to cover this stage.

It means that with a self-build mortgage that pays in arrears, you’ll normally need to have enough funds behind you to pay for each stage upfront before you get the money back from the lender. But if your available funds run out, it also raises the possibility of needing to find alternative finance to keep a project progressing until a stage is adequately completed for the cash from the self-build mortgage to be released. This could involve further borrowing, perhaps in the form of a bridging loan.

An advance mortgage

The second type of self-build mortgage involves the funds being paid out in advance of each stage of the build. This can prove a useful option if you don’t have the necessary money available to pre-fund your project. However, fewer lenders are willing to lend on this basis and if they do, the interest rates tend to be higher than on an equivalent self-build loan, which pays in arrears.

How much deposit is needed for a self-build mortgage?

The minimum deposit required to secure a self-build mortgage is often much higher than what you would need for a residential mortgage. Typically, you’ll need a minimum 25% deposit relative to the overall value of your build, although some lenders may accept as little as 15%. However, sometimes this could rise to as much as 50% for larger and lengthier projects, potentially putting a significant dent in any capital you may have for the build.

» MORE: How much deposit should I put down?

Do you pay stamp duty on a self-build property?

Normally stamp duty is only payable on the cost of the land itself rather than the value of property once it has been built. So under the current rules, you’ll therefore only need to pay stamp duty if you pay more than £125,000 for your land – this figure relates to residential stamp duty rates in England and Northern Ireland.

Stamp duty is different if the land you are buying is in Scotland and Wales. In Scotland, you need to pay land and buildings transaction tax if the land is worth more than £145,000. In Wales, land transaction tax kicks in for land that you buy that costs more than £180,000.

» MORE: Learn about stamp duty

There may be certain circumstances where non-residential stamp duty rates will apply for self-build plots, under which tax only becomes payable if you bought the land for more than £150,000 in England, Northern Ireland and Scotland and £225,000 in Wales – one potential example is where the land purchased wasn't part of the gardens or grounds of an existing home and building works haven’t yet started. However, the criteria for qualifying for this higher nil-rate band is a complicated area to unravel. For this reason, it’s always best to seek expert advice if you’re unsure how much stamp duty you need to pay.

Applying for a self-build mortgage

Self-build mortgages tend to be more complicated to arrange than a standard residential mortgage, so you should expect to spend longer preparing the necessary documentation.

Before a self-build mortgage can be agreed, applicants are usually asked to provide detailed build plans, drawn up by a reputable architect, and proof of planning permission for the build. As well as having a suitable deposit, you’ll also need to demonstrate that your sums add up in relation to the build costs, and that you have contingencies in place should you exceed your stated budget. You may also need to reveal where you will live while your home is being built and how you will pay for this.

As with any mortgage application, your lender will want to see proof of your earnings, while a good credit score can help secure an approval.

As self-build mortgages are not as readily available as residential mortgages, you may find it beneficial to use a specialist mortgage broker to help you find a suitable lender. The professional support available from a mortgage adviser may also prove invaluable as you move through the process in general.

» MORE: How a mortgage adviser can help you

About the authors:

Jim brings together unique data insights, contextual knowledge and thought provoking themes, to shed new light on important issues affecting both UK businesses and individuals. Read more

Tim draws on 20 years’ experience at Virgin Money, Moneyfacts and Future to pen articles that always put consumers’ interests first. He has particular expertise in mortgages, pensions and savings. Read more

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