Extending a terraced house
Reviewed October 2026 · Not legal, planning or financial advice
Terraced houses — Victorian and Edwardian terraces in Dublin and other cities, and later suburban terraces — have narrow plots, party walls on both sides and often short gardens.
What usually works
- A side-return infill to widen a galley kitchen.
- A modest single-storey rear extension, sized to leave 25m² of garden.
- An attic conversion with rear rooflights or a rear dormer.
Watch for
- Party walls on both sides: neighbour engagement, and structural care with old masonry.
- Rear access: in many terraces the only way to the garden is through the house, which affects how materials and waste move.
- Older houses: lime mortar, shallow foundations and damp — and whether the house is a protected structure or in a conservation area.
- Drainage often shared or running under neighbouring gardens.
Planning
The upper-floor allowance (12m²) and the 2m boundary rule make two-storey rear extensions on terraces hard to do as exempted development. Check whether your street is in an Architectural Conservation Area.
Regulations and their interpretation change. This guide explains the position as we understand it in October 2026. Confirm what applies to your house with an architect, planning consultant or your local authority before relying on it.