Chapter 9 of 10 · Self-build, extending and renovating · 8 of 8
Self-build mortgages: the deposit, the stages, the certificates and Help to Buy
Checked 21 Oct 2026the Central Bank's mortgage measures, Revenue's rules and the scheme operators' published terms.
How self-build mortgages work: the deposit, typical stage drawdowns, certificates for each stage, interest during the build and Help to Buy.
Check before you hire: a architect should be on the register kept by the RIAI. RIAI: register of architects
Written in plain English for the person buying, selling or switching. This guide covers the Republic of Ireland only.
A self-build mortgage pays for a house that does not exist yet. The lender cannot hand over the full loan on day one, because there is no house to secure it on. So the money comes in stages, as the walls go up, against certificates from a professional who has seen the work. This guide explains the deposit, the stages, the certificates, the interest during the build, and how Help to Buy fits in.
How it differs from a normal mortgage
| Buying a house | Building a house | |
|---|---|---|
| The loan is paid | All at once, on closing | In stages, as each part is built |
| Security | The house | The site, then the house as it rises |
| Who signs off | Your solicitor | Your engineer or architect, at every stage |
| Repayments during the process | None until drawdown | Interest only on what is drawn |
| Help to Buy | Paid to the builder at contracts | Paid into your loan account at the first stage |
| Time to full drawdown | One day | Usually 12 to 24 months |
The Central Bank rules still apply
The limits are the same as for any buyer. A first-time buyer can borrow up to 4 times gross income and up to 90% of the cost. A second or subsequent buyer can borrow up to 3.5 times income and 90%. Lenders add their own tests: a stress rate, your income after the repayment, and your age at the end of the term.
The "cost" is the site plus the build. If you already own the site, or it is being gifted by family, most lenders count its value as part of your 10%. A site worth €80,000 on a €400,000 build is a 20% deposit before you have saved a cent, though the lender still wants to see that you can fund the build and a contingency. The how much can I borrow tool shows your income limit.
A worked example
Ciara and Tom are first-time buyers with a joint income of €110,000. Tom's parents are gifting a site worth €80,000. The build is 180 square metres at a typical €2,200 a square metre, so €396,000 (a planning figure; see the how to self-build guide for where that number comes from). The finished house is valued at €476,000.
- The income limit is 4 times €110,000, which is €440,000.
- The lender agrees a loan of €360,000, which is 91% of the build cost and 76% of the finished value, well inside 90% of the total cost once the site is counted.
- Help to Buy: the approved valuation of €476,000 is under €500,000, and the €360,000 loan is above 70% of it. The refund is 10% of the valuation capped at €30,000 (€35,000 announced in Budget 2027, not yet law; see the changes page). Revenue pays €30,000 into the loan account at the first drawdown.
- They need €36,000 of their own money, plus a contingency the lender asks to see, typically 10% of the build cost.
The self-build mortgage calculator runs these figures for your own site and build.
What the lender asks for
Before it agrees the loan, the lender wants:
- Full planning permission for the house, with the conditions.
- Detailed drawings and a specification.
- A fixed-price contract from a builder, or, if you are using direct labour, a costed schedule from a quantity surveyor.
- Proof you own the site, or the gift letter and the solicitor's confirmation.
- A letter from your supervising professional agreeing to certify the stages.
- Evidence of a contingency fund for cost overruns.
- The usual income, savings and credit documents.
Your supervising professional is an architect (the RIAI register; see the architect page), an engineer or building surveyor (Engineers Ireland or the SCSI; see the structural survey page). The lender keeps a list of professional bodies whose members it accepts.
The stages
Each lender sets its own stages, but a typical schedule looks like this:
| Stage | Released when | Typical share of the loan |
|---|---|---|
| 1 | Foundations poured and the site ready | 10% to 15% |
| 2 | Walls built to roof level (wall plate) | 20% to 25% |
| 3 | Roof on, windows and doors in (weathertight) | 20% to 25% |
| 4 | Plastered, with plumbing and wiring first-fixed | 20% to 25% |
| 5 | Finished, with the final certificate signed | The balance |
The shares are typical, not a rule. Some lenders release the site cost first if you are buying the site with the loan. Some hold back a retention until the final certificate and the BER are in.
The certificates
At the end of each stage your supervising professional visits the site and signs a stage certificate. It says the stage is complete, built to the drawings, and that the money so far has gone into the build. The lender releases the next payment on that certificate, usually within a week or two.
Build the professional's visits into your timeline. A builder waiting for money because the engineer could not visit for ten days is a common delay. Agree the schedule of visits at the start and the fee for each one.
At the end, the professional signs a certificate of compliance with planning permission and the building regulations. The lender needs it, and so does anyone who ever buys the house from you.
Interest during the build
Most lenders charge interest only on the amount drawn while the house is being built. That keeps the payments small at the start. Say the rate is 3.5%. After stage 1 you have drawn €50,000, and the interest is about €146 a month. After stage 3 you have drawn €230,000, and it is about €671 a month. When the final stage is drawn, the loan switches to full repayments of capital and interest over the term. On €360,000 over 30 years at 3.5%, that is about €1,617 a month. The repayment calculator shows the figure for your own numbers.
If you are renting while you build, you are paying rent and interest at the same time for a year or more. Budget for it.
Help to Buy on a self-build
Help to Buy is a refund of income tax and DIRT paid over the last four years, up to 10% of the price, capped at €30,000. Budget 2027 announced a rise to €35,000 from 7 October 2026; it is not law until the Finance Act 2026 passes. On a self-build, the "price" is the approved valuation of the finished house, which must be €500,000 or less. The mortgage must be at least 70% of that valuation. Everyone on the loan must be a first-time buyer.
You apply on Revenue's online services before the first drawdown. Revenue pays the money into your loan account at that drawdown, which reduces what you borrow. You must live in the house for five years once it is finished, or Revenue can claw the money back. The Help to Buy guide explains the rules, and the Help to Buy calculator gives your figure.
The First Home Scheme on a self-build
If the loan and your savings do not cover the build, the First Home Scheme can take an equity share in a self-build. The share can be up to 30% (20% with Help to Buy), within the price ceiling for your council. See the First Home Scheme calculator and the counties page for the ceiling.
Where it goes wrong
- The build costs more than the quote. Prices move, and the ground can hide surprises. The contingency is for this. Without one, you run out of loan before the roof is on.
- The valuation at the end comes in below the cost. The lender lends on the lower of cost and value. A house that costs €450,000 to build and is valued at €400,000 leaves a gap you fill.
- The certificates are late. See above.
- The loan offer expires. Offers usually run for six months; a build runs for a year or two. Agree the extension terms at the start.
- Direct labour with no quantity surveyor. Lenders are wary of it, and so should you be. Get a costed schedule before you start.
Where this leaves you
Put your site, build cost and income into the self-build mortgage calculator to see the loan, the stages, the interest during the build and the Help to Buy refund. The self-build journey lists every step from site to BER, and you can get quotes for the architect or engineer who signs the certificates.
Questions people ask
How does a self-build mortgage work in Ireland?
The lender agrees a total loan, then pays it out in stages as the house goes up. Each stage is released when your engineer or architect certifies the work is done. You pay interest only on what has been drawn until the house is finished.
How much deposit do I need for a self-build?
The Central Bank rules apply: a first-time buyer can borrow up to 90% of the cost, so you need at least 10% of the site and build cost between you, and up to 4 times your gross income. If you already own the site, most lenders count its value towards your deposit.
Can I get Help to Buy on a self-build?
Yes, if everyone on the mortgage is a first-time buyer, the approved valuation is €500,000 or less, and the mortgage is at least 70% of that valuation. Revenue pays the refund into your loan account at the first drawdown.
Do I pay the full mortgage during the build?
No. Most lenders charge interest only on the amount drawn so far, so your repayment starts small and grows with each stage. Full capital and interest repayments usually start when the final stage is drawn.
Who signs off each stage of a self-build mortgage?
An engineer, architect or building surveyor on the lender's list, who visits the site and signs a certificate that the stage is complete and the money spent as planned. The lender releases the next payment on that certificate.