Mortgage Interest During Build in Ireland — How It Works, What It Costs, and the Trap
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Self-build mortgages in Ireland: interest only on the drawn amount during the build. Not on the full mortgage from day one. A €300k mortgage at 4.5%: stage drawdowns of 15% per milestone (foundation, wall plate, roof, weathertight, first fix, second fix, completion). Interest starts small (€168/month at 15% drawn) and grows to €1,125/month at 100% drawn. Plan for the interest cost during the build. €6,000–€15,000 over 12–18 months. Factor it into the cashflow. Some lenders offer a fixed interest rate for the build period; check before you sign. The standard variable rate is typically 4–5% in 2026.
TL;DR
Self-build mortgages in Ireland: interest only on the drawn amount during the build. Not on the full mortgage from day one.
A €300k mortgage at 4.5%: stage drawdowns of 15% per milestone. Interest starts small (€168/month at 15%) and grows to €1,125/month at 100%.
Plan for the interest cost during the build. €6,000–€15,000 over 12–18 months. Factor it into the cashflow.
When this matters most
You're planning the cashflow for the build.
When this doesn't apply
The mortgage is fully drawn down.
Frequently asked questions
How does mortgage interest work during a self-build?
Interest only on the drawn amount, not the full mortgage. Stage drawdowns of 15% per milestone. Interest starts small and grows as the drawdowns increase. Plan for €6k–€15k over 12–18 months.
What is the interest rate for a self-build mortgage in Ireland?
Standard variable 4–5% in 2026. Some lenders offer a fixed rate for the build period (typically 2–5 years). Check before you sign.
Can I get interest-only on a self-build mortgage?
Yes, the standard for self-build mortgages is interest-only during the build. Converts to capital and interest at completion.
Sources
HomeBond, Structural warranty. https://www.homebond.ie/
Frequently asked questions
How does mortgage interest work during a self-build?
Interest only on the drawn amount, not the full mortgage. Stage drawdowns of 15% per milestone. Interest starts small and grows as the drawdowns increase. Plan for €6k–€15k over 12–18 months.
What is the interest rate for a self-build mortgage in Ireland?
Standard variable 4–5% in 2026. Some lenders offer a fixed rate for the build period (typically 2–5 years). Check before you sign.
Can I get interest-only on a self-build mortgage?
Yes, the standard for self-build mortgages is interest-only during the build. Converts to capital and interest at completion.