Villa KBWW. Dubbel woonhuis in Utrecht van Bjarne Mastenbroek en Winy Maas / Villa KBWW. Double house in Utrecht by Bjarne Mastenbroek and Winy Maas

In modern architecture the wall has been reduced to the finest of pencil lines, an anonymous resource within a construction of maximum efficiency. If they had it their way, some architects would banish the wall from their buildings altogether, as MVRDV have demonstrated with their Villa VPRO. Its open spaces afford optimum flexibility – thereby maximizing the interaction between the staff of different departments – while wall-less facades ensure total transparency. In this Utrecht double villa, however, the wall takes centre stage. Programmatically and conceptually it occupies a dominant position as a zigzagging party wall between the two dwellings (and has been left in view in the exterior as a result). Paradoxically, it is virtually disregarded as a structural element.

The double villa is one of a row of modernistic ‘architect-designed’ villas which in turn form part of a long facade of nineteenth-century mansions that follows the contours of the park. The villa – named KBWW after the initials of the client – was built on the very last plot. The original buyer did not need all the space, nor could they afford to have an entire house built. They eventually managed to find a partner who was willing to take over part of the space. One owns a third, the other two thirds. A scrupulous search narrowed the potential architects down to Bjarne Mastenbroek of De Architectengroep and Winy Maas of MVRDV. Mastenbroek was given the commission, but proposed collaborating with Maas.

Meandering party wall

As the design phase progressed, the villa evolved into an `old-fashioned’ case study house. The architects soon opted for a cube shape, vertically divided into two dwellings occupying a third and two thirds of the space respectively. To give the occupants of the smaller block a sizeable living room it was decided to allow the rooms to intrude into the volume of the other dwelling. This gave rise to a meandering party wall, which defines the character of the double villa. Next, the other rooms were fitted into the puzzle over the five floors, in accordance with the occupants’ needs (with the focus either on the garden or the roof terrace).
Abandoning the strictly vertical party wall gave Mastenbroek and Maas the flexibility to spatially organize the villa as efficiently as possible. In their concept the party wall is not construed as an aesthetic, zigzagging pencil line but a thick wall that has been hollowed out. The architects hark back here to building practices of bygone centuries when the walls had to be structurally thick enough to allow mole-like hollows to be scooped out of them. Mastenbroek and Maas’s villa is in effect a stacking of hollow cavities interconnected by open staircases and voids, the only enclosed areas being the bedrooms, small contained boxes suspended in space.
Almost none of the walls in the villa are positioned one above the other. Only the head elevations rise to the full height of the building. Columns were ruled out by Mastenbroek and Maas since they felt these would mar the spatial impact of the cavities. Structurally this makes the double villa something of a Chinese puzzle, as the loads are not always carried by upright members. And as the architects wished to make the facade as transparent as possible with full-height windows, it meant creative methods had to be devised to give the building sufficient stiffness. This play of forces was ultimately resolved using pre-stressed beams, steel rods and cleverly positioned concrete balconies. As a result, the thrust lines meander like the party wall, though they follow a different pattern.
Spatially the left-hand dwelling (viewed from the street) is more interesting than the right. The levels at the right create very fine loft-like open spaces organized in a horizontal sandwich. The left-hand dwelling is more labyrinthine. Its cavities are vertically arranged around an ‘axis’ of two stacked but slightly staggered voids. From the kitchen on the ground floor you can see right up to the roof eleven metres above. If spatially interesting as living space, the long narrow rooms are not very practicable. For this reason, the living room hollowed out of the neighbour’s volume on the third floor provides a welcome break from the verticality of this dwelling. It lends the house an airiness and provides a pause in the zigzag promenade from the kitchen on the ground floor to the terrace and bathroom on the roof. This floor is the most fanciful. The bathroom with its fully glazed wall opens onto the roof terrace, a high parapet around the roof guaranteeing privacy though a section of it can be lowered for an unobstructed view of the park. And the roof terrace offers a permanent view of the cathedral spire (the Domtoren).


A distinctive feature of the double villa is the facade. It is unusual in that it was not designed – in line with a tendency that can be observed in recent architecture. The facades of the VPRO Villa and to some extent of OMA’s Educatorium on Utrecht’s Uithof are similarly ‘skinless’. In all three schemes the floors continue as the facade and in between spaces are fully glazed all the way up. Window and door frames take over the wall’s structural function. One has the impression that the floors could run on endlessly – the architectural couterpart of ‘all-over’ compositions in painting. The ends are cut like a portion of lasagna, exposing the various layers.
In the double villa the cross-cut ‘ends’ of the floors generate a Mondrianesque play of lines. Even Mondrian’s colour planes are incorporated in the composition of the facade in the shape of the windowless walls of the bedrooms and toilet. Here glass is analogue to white, the metaphysical colour par excellence. The only finishing details in the facade are the sturdy wooden shuttering boards that clad the concrete sections.
This non-designing of the facade represents a clear break with the architecture of aestheticism successfully championed by Mecanoo. Mastenbroek and Maas strip their buildings of any superfluous cosmetic trappings and focus their creativity on designing the spatial programme. Allowing spaces to flow into one another is a major theme in this respect. It is an articulate echo of OMA’s architecture, such as the Kunsthal in Rotterdam, as well as that firm’s designs for the Library in Jussieu and the Opera House in Cardiff. Mastenbroek and Maas have no common idiom – although both of them like to work with Arte Povera materials – but they do share an interest in composing spaces within a volume as opposed to lavishly detailing the facade.
The disregard for the aesthetics of the facade has, in the case of the double villa KBWW, has resulted in a fairly forbidding building. If the dark brown of the shuttering does much to add an introverted air to the villa, the glass – and the transparency it imparts – conveys a sense of openness and accessibility. But once the Acacias are planted in the front and back gardens, in the coming years the villa will be able to withdraw further still from the public eye.

De Nederlandse delta. Off-shore discussie over Nederlandse architectuur / Dutch Delta. Off-shore discussion on Dutch architecture