Room-by-Room Brief for a Self-Build — Sizes, Adjacencies, and the Decisions That Matter
On this page
A room-by-room brief for a self-build covers the size and adjacency of every room. Standard sizes: master bedroom 14–18 m², other bedrooms 10–14 m², kitchen 18–25 m², living 22–30 m², dining 12–18 m², home office 10–14 m², utility 6–10 m², storage 8–12% of total floor area. Decide adjacencies before sizes: kitchen should be open to dining, master should have an ensuite, utility should be near the back door. The wrong adjacency is a daily annoyance and very expensive to fix later. Total floor area for a 4-bed home with three occupants: 180–220 m². Add 10–15% for circulation (hallways, stairs) and walls. Your architect will redraw if your room-by-room brief doesn't add up to a viable plan, but the brief is the right place to start.
TL;DR
Master bedroom 14–18 m². Other bedrooms 10–14 m². Kitchen 18–25 m². Living 22–30 m². Storage 8–12% of floor area.
Decide adjacencies before sizes: kitchen to dining, master to ensuite, utility to back door. The wrong adjacency is a daily annoyance.
Total floor area for a 4-bed 3-person-occupant home: 180–220 m². Add 10–15% for circulation and walls.
When this matters most
You're writing the design brief and need to decide room sizes and adjacencies.
When this doesn't apply
You've already lodged planning drawings.
Frequently asked questions
How big should a master bedroom be in a self-build?
14–18 m² is standard for a UK/Irish self-build. 12 m² is workable but tight. 20+ m² is luxury.
How big should a kitchen be?
18–25 m² is standard for a self-build with an open-plan living/dining. 12–15 m² is workable for a separate kitchen. 30+ m² is luxury.
What is the right size for a 4-bed self-build?
180–220 m² is standard for a 4-bed home with three occupants. Add 10–15% for circulation and walls. Smaller is possible (140 m²) but compromises storage and living space.
Sources
Royal Institute of the Architects of Ireland, Housing standards. https://www.riai.ie/
Frequently asked questions
How big should a master bedroom be in a self-build?
14–18 m² is standard for a UK/Irish self-build. 12 m² is workable but tight. 20+ m² is luxury.
How big should a kitchen be?
18–25 m² is standard for a self-build with an open-plan living/dining. 12–15 m² is workable for a separate kitchen. 30+ m² is luxury.
What is the right size for a 4-bed self-build?
180–220 m² is standard for a 4-bed home with three occupants. Add 10–15% for circulation and walls. Smaller is possible (140 m²) but compromises storage and living space.