Beata Heuman brings colour, texture and softness to a contemporary London house

A few years ago, an internationally acclaimed musician stumbled across Beata Heuman's book Every Room Should Sing. 'They liked the title - I think they took it as a sign,' says the interior designer, who was subsequently enlisted to decorate their new family home in London. Built in the 2010s and designed by its former owner, an architect, the house was a departure for Beata and her team. It was the first time she had worked on a contemporary house that she had not been involved in from the build stage, so she did not have any input on the finishes or layout. "The house was so freshly done, it felt far too wasteful to pull everything out and start again, so we kept the kitchen, the staircase, the bathrooms and the wardrobes. The challenge was working within those parameters in a way that felt appropriate. This project is quite a different expression of our work in many ways because of that.'

Spread over three floors, the house has two large, open-plan, central rooms, one on the entrance level and the other below, with a wall of windows overlooking a lush Japanese-style garden. "There were a lot of hard, shiny surfaces,' says Beata. "The first thing I wanted to do was soften everything and create a feeling of connection with the garden by bringing in natural materials. Generally, when designing, I'm thinking about what was happening around the time that a house was built, then adding a little from that decade and every subsequent one, to make the space feel evolved. Here, we couldn't really follow that method. It didn't feel right to go much further back than mid-century?

Luckily, the owner wanted to invest in some special pieces. In the upstairs drawing room - a grown-up space for reading, listening to music and entertaining - Beata has used a melange of interesting Scandinavian designs. It is a room of strong, elegant shapes typified by its library corner, which has been created using a bookshelf and chaise longue by pioneering mid-century Swedish designer Bruno Mathsson. 'What I like about Swedish design from this period is the clever use of humble materials. The designs have a boldness that really appeals to me, but they are also quite pared back and earthy,' explains Beata.

On the other side of the room, a bioethanol fireplace set in a black Formica cabinet was removed and replaced with a wall of bespoke joinery in toffee-coloured oak. A long; low section houses a record player and a corner cupboard conceals a fridge, allowing a desk to instantly morph into a drinks table. Unable to add a working chimney, but feeling that the room needed a focal point, Beata created a sculptural plaster hood above a panel of Swedish Green marble. In front of this is a cluster of beeswax candles that, she explains, in lieu of a real fireplace, 'creates a gathering place around fire. Lighting the candles feels like a bit of a ritual - there's something quite magical about it.' Also for this space, Beata commissioned an ottoman making use of a 1930 tapestry design by the celebrated early-20th-century Swedish textile artist Märta Maās-Fietterström: 'It was the first time that the weavers in the south of Sweden, where her designs are traditionally made, had ever done something like that. So it's a really special piece.'

Leaded-glass doors were installed to create a view from the front door to the back garden. 'It's a simple trick that helps you understand the depth of the house as soon as you come in,' says Fosca Mariani, Beata's head of interior design, who worked with her on the project. Down a black spiral staircase to the lower-ground floor, hung with an Isamu Noguchi paper lantern, is the owner's new recording studio, which has Josef Frank curtains and a bespoke sound desk. A spare room for guests on the same floor has sand-coloured seagrass on the walls and ceiling, and new wardrobe doors in green and ivory tadelakt. 'It is lovely because it has a bit of movement in it,' says Beata.