| The buildings differ from traditional housing mostly in the execution quality. Each surface-ceilings, floors and walls – is smooth as a mirror; even angles remain perfectly right.
Since the early 1990s, the Kraków-based company of Buma, which is an architectural and a property development company, has been attempting at the creation of dwelling houses to be made in whole of prefabricated modules. Each of Buma's projects involves its own, original construction system. For several years, Buma has implemented its Free-Dom building system, which is based on steel structures, with lightweight clay aggregate concrete walls. As the very name implies, the system allows for a high freedom, and each time it is adjusted to specific projects, hence there are so different outcomes, like Onyx housing complex in Kraków, or a single-family development in London. In order to save on designing process, one and a half year ago Buma created a special assembly line for the ready-made buildings. Homes under the new system (Bumati) are available in a few models only, however, with different furnishings. The only things to be made on a land plot (that has already been provided with utility infrastructure) are the foundations and standard utility connections, whereas all other works, including finishing, take place in the factory. It is just in that way they the model set of four homes installed in a picturesque quarry at Rząska near Kraków was constructed.
Both in their architectural form, and in construction, the modern-style, minimalistic Bumati houses differ completely from other catalogue houses, which are available on the Polish market. They are a fulfilment of a modernistic dream of a building without heavy walls, foundations, and high roofs. Set on steel columns, the Bumati houses seem to be levitating.
I-section beams, like those in Mies van Rohe's Farnsworth House, are not only structural members, but elements of the composition as well. They create frames for the floor and flat roof planes, and their horizontal lines delimit cuboidal shapes of the building from its top and bottom.
It takes only one day to erect a single-module house on site. Such a short time and lack of any earthmoving works on site cause that the ecosystem of the land plot remains intact. Dimensions of modules result not so much from the fabrication technology, as from the shipment limitations. In order for a module to be loaded on a lorry truck, it needs to be maximum 4 metres wide and a dozen or so metres long. The clear height is 2,68 metres. The I-section frames with steel studs and lightweight clay aggregate concrete walls, 25 cm thick, form a rigid structure, which can withstand transportation and lifting by means of a crane (Bumati houses are three times lighter in weight than traditional houses). Upon delivery to the site, each module is already fully completed – it has all the systems and services, floor, wall and ceiling finish, windows and doors, as well as a completely furnished kitchen and bathroom, and built-in wardrobes.
Despite prefabrication, the authors of the Bumati concept managed to obtain a high variety of types – from small houses for guests, or garden pavilions which can be set even on wheels like trailers, to large vacation houses and all year-round residences of the surface area of up to 300 m2. Elevations are available in a wide range of colours and materials, from the cheapest solutions, that is plaster, to exotic wood cladding systems, or smooth Trespa panels. Clients can also choose from a variety of external elements, such as terraces, stairs, canopies over doors, or steel pergolas, thus providing an individual character to the final appearance of their homes. Also present are solutions typical for luxurious architecture: glazed walls extending from the floor up to the ceiling, wood finishing elements, large terraces. The steel structure of the building makes it possible to even create glass pane wall corners.
The buildings differ from traditional housing mostly in the execution quality. All surfaces – ceilings, floors and walls – are perfectly smooth, even angles remain perfectly right. The fabrication of modules in the factory has the advantage of subjecting each production stage to strict supervision and control.
Unfortunately, those houses are not cheap. Depending on the quality of finish and size, they cost PLN 4,000-7,000 per sq.m. This is not a home for everybody (so far, not many Bumati houses have been sold), as was the original intention of Le Corbusier or Jean Prouvé, who designed buildings to be constructed on a large scale. Still, in future, in the event of a large-scale production, prices would certainly go down. The question is, however, whether the system of light and movable homes, which at any moment can be disassembled and moved into another place, can find a place on the Polish housing market. This does not seem to correspond with the Polish archetype of home as a sanctuary and retreat.
Bumati designer's assumptions:
When you say Bumati, you mean, first of all, flat roofs, glazings to the full interior height, large terraces and modern wall cladding systems, which include, among other materials, HPL panels and exotic wood boards. The buildings are composed of volumetric modules.
Those modules are manufactured in the factory, complete with elevations, windows and doors, as well as electrical, sewage, water and heating systems. External walls, which are cast in moulds, are made of lightweight clay aggregate concrete, and perform very well in terms of sound reduction and thermal insulation (0.18 W/m2K).
The multi-layer structure of floors, additionally provided with thermal insulation, makes it possible to move the buildings away from the ground, and to put them up on different height piles.
One can order a Bumati house completely finished. The turnkey version (with glazed tiles on bathroom and kitchen walls, fixtures and sanitary ware, as well as built-in furniture) is assembled in the factory, thus making it possible for the buyer to use the home immediately after it has been erected. Bumati is a very good solution for active people, who prefer comfort and convenience to stresses and problems related to the traditional construction process.
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