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Self Build Mortgages

Updated: Apr 5, 2023

If you are planning to build your own home on a site you already own, or intend to purchase you will need flexibility in terms of your mortgage drawdown. You want to be able to drawdown the mortgage in stages as the building progresses. Otherwise you would end up paying back a full mortgage while your home is still partly under construction.

How much deposit do I need for a self build mortgage?

Generally you will need to put down a deposit of at least 25% of the total project value, though in some cases you may be asked to put down as much as 50%. Bear in mind that you you will need to pay for alternative accommodation during your new build.

How can you finance your self-build property?

The most common ways people fund their self-build are the following:|

  1. Sell your existing home

  2. Self-build mortgage

  3. Cash

  4. Remortgage your home

How much can I borrow for a self build mortgage?

The maximum you can borrow is 3.5 time your annual gross salary. This is based on a single income applicant. If it is a dual application it is 3.5 times both salaries combined. (Some exceptions may apply).

Can I use a site as a deposit for a mortgage?

There is nothing to stop you from using your site as a deposit for your mortgage. However your lender is not obliged to accept it, so you should check this in advance. An experienced broker can do this for you. We would expect that any lender would want to see that there is planning permission for the site if it was being used as a deposit.

Is a self build mortgage more complex than a regular mortgage?

Due to the nature of the stage payments of a self-build mortgage this would mean that the process is naturally more complicated than a regular mortgage, so some patience is required.

What is the lending criteria for a self build mortgage?

When assessing a self build mortgage application lenders apply the same criteria to a self -build as they do with a normal house purchase. As with all mortgages they need to satisfy themselves that you can afford the mortgage repayments.

How much money can I draw down for my self-build mortgage?

Mortgages are generally 3.5 times gross annual income and 80% of the property value. With a self-build mortgage, the property value is usually calculated as either the site cost ( if this is applicable) plus building costs or the final valuation upon completion of the project. We would advise to have an extra 10% of the total cost to cover unforeseen expenses and potential cost over-runs. There is no penalty if you don’t draw down the funds you originally applied for.

Should I use a Mortgage Broker for my self-build mortgage?

Yes it makes total sense to get an adviser who specialises in mortgages to shop around for you for your self-build mortgage. Different lenders treat self – build mortgages in different ways.

If you have a query about self-build mortgages, we’d love to help

Get in touch by calling us on (01) 513 8710 or emailing on

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