The Roundhouse: A Sustainable Five-Bedroom House in the Hertfordshire Countryside
Set in open countryside near the quiet hamlet of Old Knebworth, Hertfordshire, this extraordinary five-bedroom home offers a one-of-a-kind living experience.
Built on the site of a disused water tank, the Roundhouse is a circular, three-level home that seems to grow out of its surroundings.
Its sweeping roofline and central “tree-like” core create an organic flow, while over 4,800 sq ft of space provides room for both everyday life and creative work.
Sustainability and craftsmanship are at the heart of the design. The house is built almost entirely from reclaimed and local materials, firmly rooting it in the landscape.
The concrete lid of the old reservoir was crushed to form the façade, while original Edwardian steel struts were repurposed to support the balcony. All the timber, larch, ash, and oak were sourced and milled less than a mile away at the neighbouring Knebworth House estate.
Even the construction process was mindful: materials were carried in by hand to protect the surrounding woodland.
The Roundhouse is designed to run almost entirely off-grid. A septic tank, solar panels, wood-fired range, and clever rainwater collection from the conical roof make it impressively self-sufficient. Thermally broken Crittall windows improve energy efficiency, while lightwells brighten every level with natural daylight.
Tucked away on a country lane, the property feels tranquil and secluded from the moment you arrive. A tree-lined path winds through the grounds, leading to a moated pedestrian entrance, while a gated driveway provides plenty of parking.
The exterior blends stone, Lutyens-inspired red brick, and Edwardian concrete into a striking patchwork, with bee bricks cleverly incorporated to support pollinators.
Above, a tiled conical roof is crowned by a weathervane, while glass panels encircle the home to bring the outside in. The main entrance sits on the first floor, reached by an external staircase.
Inside, the tone is calm and natural. A welcoming porch with skylights and stone floors opens to a handcrafted wooden staircase.
At the top level, the entire floor is dedicated to a sweeping open-plan living area. Floor-to-ceiling windows create panoramic views and blur the line between indoors and out.
Vaulted ceilings, skylights, and a warm palette of natural materials, solid larch floors, clay plaster, and handcrafted joinery make the interiors feel bright yet grounded. At the centre, the chimney-like core distributes warmth throughout.
The kitchen is anchored by a red Thornhill range cooker with a tiled splashback, oak-topped island, and solid wood cabinetry. A tucked-away prep kitchen offers extra storage and modern appliances.
Two living zones suit different moods: one opening to a large balcony for outdoor dining and countryside views, the other cosy with a wood-burning stove. A mezzanine “crow’s nest” above makes the perfect study or retreat.
The first floor holds five bedrooms, all designed in a soft, neutral palette. The principal suite opens directly onto the garden and has an ensuite with a roll-top bath and encaustic tiles.
A guest suite has its own ensuite shower room, while three further doubles share a colourful family bathroom with both bath and walk-in shower.
Downstairs, the Roundhouse reveals even more surprises. A reclaimed brick archway leads to a full oak bar and generous dining space, ideal for entertaining. Beyond are a gym/studio/theatre room, wine cellar, utility, laundry, and extra storage.
Wrapped in landscaped gardens, the home enjoys total privacy. Mature oak and fir trees, hedgerows, lawns, terraces, and shingled paths create a natural, ever-changing setting.
To the rear, a large paved terrace offers shaded outdoor dining, while the upper balcony feels like a private treetop retreat.
The Roundhouse is listed for £2,650,000 at The Modern House.