Martin and Alison Long’s home is a three-storey high structure with six bedrooms and as many bathrooms, yet you can’t see the house for the trees until you are nearly upon it.

The use of natural materials, including expanses of glass, vertical timber panels that echo tree trunks and mineral renders the colour of overcast sky, ensures this contemporary home blends in with its setting: a clearing surrounded by mature trees and dense shrubbery. The building is effectively camouflaged within a woodland glade. Glimpsed through the trees, the overall impression is of dappled light.

That’s just what the couple wanted - their home to have minimal visual impact on its location, an arboretum within Sir Harold Hillier’s Gardens, considered one of the most important plant collections in the world.

Alison comments: ‘If you are walking in the arboretum, you wouldn’t know the house is here.’

Alison and Martin have lived in their house since 2022Alison and Martin have lived in their house since 2022 (Image: Joakim Borén) Limed oak feature walls create a stunning space between roomsLimed oak feature walls create a stunning space between rooms (Image: Joakim Borén) The house appearing unexpectedly is not the only surprise. This is also an ‘upside down’ house. The floor plan has been inverted with bedroom suites on the ground floor so that the principal living spaces on the first floor enjoy views through the trees and more light.

However, the greatest surprise is that this building is a ‘prefab’, built in modules off-site. This is not a prefab as most consider it. This bespoke home takes prefab construction to a new level with Baufritz (UK) Ltd successfully adapting the design by Winchester-based, award-winning architectural practice McLean Quinlan to their modular system.

This way of building is more environmentally aware. It had always been the couple’s intention to build a home with a light environmental footprint, and a plot within the arboretum necessitated that.

Martin and Alison have cleverly used unique furniture to zone the main living areaMartin and Alison have cleverly used unique furniture to zone the main living area (Image: Joakim Borén) The stunning kitchen is by bulthaup from Hobson's Choice in WinchesterThe stunning kitchen is by bulthaup from Hobson's Choice in Winchester (Image: Joakim Borén) Hampshire County Council, as trustees of Sir Harold Hillier Gardens, was involved in the planning process, as well as the local council. Initially concerned about what Alison and Martin were going to do with the original property, which had been used to accommodate agricultural students from around the world, they loved the idea of them building this type of modern house. Their main concern then became the protection of the arboretum’s plants and roots, to ensure they weren’t damaged in the build process. They needn’t have worried: Alison and Martin and Baufritz were determined to deliver that level of duty of care anyway.

Alison says: ‘The company was wonderful, very environmentally conscious, with their ethos and values [to build homes that are healthy to live in and make responsible use of nature’s resources] running through their staff, who were all lovely and calm.’

As a Grand Design story Kevin McCloud would be disappointed. This project ran smoothly without drama.

The fire in the cosy sitting room is mostly for show as the house has an air source heat pumpThe fire in the cosy sitting room is mostly for show as the house has an air source heat pump (Image: Joakim Borén) Alison continues: ‘We have done other building projects, including a new home in Cornwall, but building this way with this company has hands down been the best experience!’

As seasoned builders and doer-uppers, the pair knew exactly what they wanted, which also helped the process. Martin comments that the architects got the brief right from day one. The only delays were out of their control – namely Brexit and Covid. This meant that, having started the project in 2016, the units, built off-site in Germany, were not delivered until 2021. However, following the modules’ transportation to site, on 16 low-loaders, it took less than 10 days to put the house together. More accurately they were delivered to a nearby nursery where they were ‘decanted’ onto smaller vehicles, to protect the arboretum’s trees and their roots.

The couple moved in at the end of 2022, with garden landscaping and naturalistic planting such as grasses, to soften the angular structure, taking another six months.

This bespoke home This house takes prefab construction to a new level with Baufritz (UK) Ltd leading the way This bespoke home This house takes prefab construction to a new level with Baufritz (UK) Ltd leading the way (Image: Joakim Borén) The result is stunning – three volumes, each with different dimensions and different facades, stacked upon each other. The middle section, dominated by the principal living spaces, overhangs the lower ground floor section, while the top section, featuring a curving butterfly roof style design, is smaller. This allows a setback from the section below, creating character, shape and privacy for the top floor’s master bedroom suite and study.

From everywhere in the house the backdrop of trees can be glimpsed. The ground floor, with boutique hotel style bedroom suites and calm room for playing the piano or reading a book, feels more ‘cocoon-like’. The best views are from the first floor where elegant grey floor tiles in the main kitchen-dining-living room as well as the ‘evening’ sitting room, run through to the dining and seating terraces, creating a sense of continuity between indoors and outdoors. The higher you go, the lighter the spaces.

Alison says, ‘On the top floor it feels like a treehouse as you are among the treetops.’

The interiors reflect the leafy surroundings with a muted colour scheme and natural materials The interiors reflect the leafy surroundings with a muted colour scheme and natural materials (Image: Joakim Borén) Expanses of glass and glass roof panes above the stairwell, which runs through the full height of the building, allow light to stream in through the leaf canopy, bathing the interiors in a mosaic of light and shadow that shifts the mood of the house through the days as well as the seasons. This means that even inside you feel immersed in nature, and there is a meditative sense of wellbeing. Alison is a yoga instructor and exudes a similar calm serenity as her home (there’s an impressive black timber clad yoga studio and gym in the garden behind the house).

Alison continues: ‘Calm was the objective.’

The interiors reflect the leafy surroundings with a muted colour scheme and natural materials such as handcrafted oak joinery, including limed oak feature walls, doors and shelving by Ridon Joinery, a specialist business in Southampton.

On the top floor it feels like a treehouse as you are among the treetops' says AlisonOn the top floor it feels like a treehouse as you are among the treetops' says Alison (Image: Joakim Borén) Alison adds: ‘I prefer to live with plains and neutrals, and the palette outside is worth leaning into.’

The vast kitchen-dining-living space is the heart and hub of the house. The room’s layout was inspired by the kitchen in their previous home, an older property where they had lived for 20 years and brought up their four children. That kitchen had an Aga one end, a fire at the other, and a big square table in the middle - now repurposed as two desks in their shared top floor study as they didn’t want to part with it. They have evolved that layout, breaking up this large space into zones and making the room feel surprisingly intimate.

The kitchen ‘zone’ features the quiet minimalist elegance of a bulthaup kitchen from Hobson’s Choice in Winchester. It perfectly complements the restrained colour scheme with a wall of anthracite grey storage subtly hiding a scullery and wine room. This ensures the kitchen area remains uncluttered even when they’re entertaining big gatherings of family and friends. A striking feature is the centrepiece island unit with four-meter-long stainless-steel countertop, specially crafted by bulthaup in one continuous piece.

The natural materials blend seamlessly with the outside spaceThe natural materials blend seamlessly with the outside space (Image: Joakim Borén) In front of this island unit, and dominating the centre of the room, is a bespoke dining table that comfortably seats 12. In their previous home they’d had a separate dining room which was hardly ever used.

Alison says, ‘This is far more sociable, people are here while we are cooking and are part of the action.’

Attention to architectural details such as changes in ceiling height help to add character and help to define the zones. The sitting area features a deep and inviting modular sofa curving in front of a feature gas fire. However, the fires are largely decorative as the house is so warm due to its south elevation, triple glazing, thick walls, air source heat pump and Baufritz’s patented, award-winning organic wood shavings insulation.

Their children, now living in London, regularly descend for a break from the chaos and noise of city life. And the house can adapt from a place of relaxation, wellbeing and quiet contemplation for two to many, while still having a sense of being lost deep in the woods.

Alison smiles, ‘We are so lucky to be in an arboretum.’