This house extension in Dartmouth Park is designed to better connect the property to a large garden. A new dining room with oak framed sliding doors leads to a landscaped terrace, and a separate glazed evening room allows uninterrupted garden views. Between these two spaces a sheltered outdoor kitchen is created. Concrete beams at roof level create a horizontal datum across the spaces. This begins internally and continues outside to shelter the barbecue area, finally returning to the ground to form a new pergola against the garden wall. When viewed from the garden, this continuous horizontal line creates the impression of a unified, wide extension that emphasises the generous 17m garden width. Sustainability improvements include replacement double-glazed sash windows throughout and ultra high performance vacuum insulation (Kingspan Optim-R) to improve heat retention. New glass to the rear extension has a solar control coating and a U-value of 1 W/m²K. The structural beams in the extension are concrete with GGBS to reduce cement content. Underfloor heating, energy efficient appliances and low energy LED lighting were specified throughout.