Irish studio Scullion Architects took visual cues from long galleries in country homes in its design of Rathdown, a window-lined extension to a house in Terenure, Dublin.

The elongated extension contains a spacious kitchen and dining area and opens up the home's existing ground-floor living spaces, which were previously "cramped and dark", Scullion Architects said.

Its layout is modelled on a long gallery, a spacious corridor-like room lined with windows, typically found in traditional country homes and used to connect spaces while providing outward views.

"The existing house was lacking any social heart," studio director Declan Scullion told Dezeen.

"Although the original home had three generous ground floor reception rooms, their distance from the kitchen and garden views meant that none lent themselves to daily use, and the family would instead tend to squeeze around an undersized table in the kitchen," he continued.

"The long gallery was introduced to stimulate a more social home environment for the family, and act as a conduit between the existing ground floor reception rooms, hallway, and the garden."

Outside, Rathdown is defined by deep green powder-coated aluminium that is teamed with timber elements in the same hue.

According to Scullion Architects, this material palette references conservatories of a typical 1930s home in Ireland.

From inside, the extension is accessed via a cosy reading room, which connects to one of the existing reception rooms with a set of steps.

"Layering the more social programs of reading area, dining, kitchen, with the older more static reception rooms, it is hoped this new room will encourage dynamic coexistence of activities and increased interaction and communication," said Scullion.

Rathdown's kitchen and dining room feature warm-toned timber cabinetry and wall panelling, paired with minimalist stone steps and flooring.

Picture windows line the garden-facing wall, bookended by folded windows to maximise the extension's access to nature.

"Part of the role of the long gallery was to draw the sun into a north-east facing kitchen for as long as possible during the day," Scullion explained.

"The folded windows at either end flank of the long room draw in the morning sun for longer, as it tracks from east to west, but importantly it also alleviates the sense of a blinkered and bookended garden aspect," he continued.

"By extending to the side on the west, and raising a clerestory window along the west and south facing glazing to the front, this room receives sun for most of the day."

Towards the front of Rathdown, the extension has a stepped brick elevation, incorporating raised planters that help to screen the tall south-facing windows, balance balancing and natural light.

Scullion Architects is a Dublin-based studio established by Scullion in 2016. Its previous projects include the renovation of a cottage with a corrugated metal extension and a curved glass addition to a home that references Victorian conservatories.

The photography is by Johan Dehlin.