Hen Barn Annex

It is an existing redundant agricultural building converted into a four-bedroom house and received a Sussex Heritage Trust award. Sold in 2020, the new owners approached NPA to design an annex for an elderly parent. Following a pre-application process, full planning consent was granted in July 2022. Sited within an AONB, close to the Ashdown Forest and a listed Grade II farmhouse, the consent proved relatively straightforward even though the proposal was for a detached building to avoid compromising the form of the main house. As the land slopes up, Hen Barn sits near the end of the access track and extends perpendicular. The siting shields the main house from the track and the east elevation is purposefully blank for privacy from the public footpath leading onto the forest. The annex is single-storey and uses the same palette of external materials as Hen Barn—zinc roof, local stone base, and chestnut cladding. The plan is folded to accommodate the geometry of the site, with a central service core flanked by two wings, one for the bedroom and one for the open-plan kitchen/dining/living. To achieve an extremely high thermal performance and mass, the primary structure comprises clay blockwork walls overclad with timber I-beams with full-fill wood fibre insulation. The roof has 300mm wood fibre insulation, and the west-facing glazing is tilted to increase solar gain in the winter. The annex is served by an ASHP and MVHR unit, as well as a wood-burning oven in the event of a power cut.