Leo Turley (QFA)

A self-build mortgage lets you finance the construction of your own home in stages, rather than buying a finished property in one go. It’s a powerful route for people who want a say in every detail of their home – but it comes with its own rules, documentation and timelines that are very different from a standard purchase.

What is a self-build mortgage?

A self-build mortgage is designed for people who want to build their own home, or carry out a major renovation/convert an existing property, instead of buying a completed house.

The key difference is how the funds are released. With a standard mortgage, the full loan is drawn down at closing. With a self-build mortgage, the lender usually releases the money in stage payments as the build progresses and is signed off by a professional.

For the right borrower, this structure allows you to turn a site and a set of plans into a finished home – with the lender funding each major milestone along the way.

How a self-build mortgage works: step by step

The broad sequence looks like this:

Secure the site – either by buying it or using a site you already own.

Get planning permission for the home you intend to build.

Prepare your financial paperwork (income, savings, existing loans, etc.).

Submit your build details – plans, costings and builder information – with your application.

The lender assesses your case and approves a maximum loan amount under their criteria and Central Bank rules.

Funds are released in stages as the build progresses and is certified.

A final payment is released when the property is complete, certified and valued.

Throughout the process, you are working to two parallel plans: your build programme and your mortgage drawdown schedule. Keeping those aligned is crucial.

What lenders usually look for

Because self-builds are more complex than buying a finished home, lenders look closely at both you and the project. Typical requirements include:

Proof of income (payslips, contracts, or accounts for self‑employed).

Evidence of savings and your deposit contribution.

Full planning permission for the proposed build.

Detailed costings from a quantity surveyor, engineer or experienced builder.

Architectural drawings and plans, including BER/energy efficiency proposals.

A fixed‑price building contract, or clear details if you are using direct labour.

Confirmation you can complete the build within the stated budget.

Site ownership documents.

The aim is to show that the project is viable on paper – financially, technically and within the expected timeframe.

Which lenders offer self-build mortgages?

Through Irish Mortgage Corporation, the main lenders currently active in the self-build space include:

Haven Mortgages

Bank of Ireland

Permanent TSB

Each lender has its own credit criteria, maximum loan amounts and way of assessing build costs versus end value, so two banks may not give the same answer on the same project. Part of our role is to match your profile and your plans to the lender whose policy best fits what you are trying to achieve.

Borrowing rules and how much you need

Central Bank of Ireland mortgage rules still apply to self-builds, just as they do for standard home loans.

In general:

First-time buyers can usually borrow up to 4× gross income.

Second and subsequent buyers are usually limited to 3.5× income.

The minimum deposit is typically 10% of the total build cost / final value.

One important difference is how your site is treated:

If you already own the site outright, its value can often be treated as part, or all of your deposit contribution, and lenders will look at the combined picture: site value + build cost = total project value.

For example:

Site value: €100,000

Build cost: €300,000

Total project value: €400,000

If you own the site with no debt, that €100,000 can act as your equity, and the lender may fund the remaining €300,000 (subject to income and policy limits).

How stage payments and drawdowns work

Once your mortgage is approved and you are ready to build, the loan is typically drawn down in stages tied to construction milestones. A common structure might look like:

Stage 1: Foundations complete

Stage 2: Walls up / wall plate level

Stage 3: Roof on and the property is weather‑tight

Stage 4: First-fix electrical and plumbing

Stage 5: Completion – with a final 10% often held back until full sign‑off and valuation

At each stage:

Your engineer or architect inspects the work and certifies the build has reached that point.

Your solicitor requests the next stage payment from the lender.

The lender releases the funds to be used for the next phase of works.

Because builders usually need to be paid before the next certificate is issued, cash flow is critical. Many self-builds require you to have reserves or access to funds at the start and end of the project to bridge the gap between paying contractors and receiving the next stage payment.

Costs that are often overlooked

Beyond bricks and mortar, there are several expenses that frequently catch self‑builders off guard. These can include:

Septic tank or wastewater treatment system.

ESB and other utility connections.

Landscaping, driveways and boundary works.

Kitchens, wardrobes and flooring.

Professional fees (engineers, architects, surveyors, planning).

A contingency fund for overruns and unexpected issues.

Many lenders expect to see a contingency allowance of around 10% of total project costs in your figures. Building in that buffer from the start is one of the best ways to protect yourself from stress later.

How long does a self-build take and is it right for you?

Timelines vary, but a realistic outline is:

2–6 months for planning permission, design work and mortgage approval.

8–18 months for construction, depending on the size and complexity of the build, the availability of trades, and weather.

Lenders will typically require that your mortgage is fully drawn down within a set period and may impose conditions around how long the build can take. Staying on top of your schedule and communicating with your broker and lender is essential.

A self-build can be incredibly rewarding. You end up with a home tailored to your family, location and long‑term plans. But it also demands more planning, more documentation and more financial discipline than a standard home purchase.

If you’re trying to see if a self-build is right for you, here are some key questions to ask yourself:

Do you have the time and headspace to manage a build?

Are your budget and contingency realistic?

Is your income strong enough to support the borrowing you need under current rules?

Have you stress‑tested your plan against possible delays or cost increases?

Getting clear answers early will make the whole journey smoother.

How Irish Mortgage Corporation can help

If you are thinking about going down the self-build route, you do not have to figure out all of this on your own. At Irish Mortgage Corporation, we:

Work with the main self-build lenders (Haven, Bank of Ireland and PTSB).

Help you understand how much you can realistically borrow under Central Bank rules.

Review your plans, costings and timeline to spot potential issues early.

Guide you through the application, approval and stage drawdown process.

Building your own home is one of the biggest projects you will ever take on – but with the right advice and lender, it can be an achievable and hugely satisfying way to create the place you really want to live.

If you would like to explore whether a self-build mortgage could work for you, the next step is a straightforward conversation about your plans and your numbers.