At first sight, the strangely shaped, colourful house with the transparent roof appears so surreal that the visitor needs time to realise that what they see is not a figment of their imagination, conjured up in reaction to the ubiquitous mutro-Baroque castles.

From the inside, this odd building in the village of Osikovitsa, near Pravets, about 70 km, or 45 miles, northeast of Sofia, is equally unusual.

Welcome to Gradezhat, or the Construction, a perfectly habitable house, whose creator is not an architect, but probably Bulgaria's best-known contemporary sculptor. In November 2008, Pavel Koychev, aged 70, added this house sculpture to his portfolio. The artist, whose works appear in art galleries and private collections in Bulgaria, Greece, Belgium and the United States, has had more than two dozen one-man exhibitions and participated in numerous group exhibitions.

Gradezhat is not such a surprise, after all. From an artist famous for creating fantastic figures out of unusual materials, such as yarn, sticks, mud, straw, wax, Styrofoam or cloth, the result was bound to be unpredictable. Koychev prefers a delicate touch to inspire the imagination rather than employing the shock tactics typical of many avant-garde artists.

To create Gradezhat, Koychev had more space to play with than many architects enjoy. The total floor area of the house is 360 sq m, or 3,880 sq ft. The plot of land in Osikovitsa was given to him by Miroslav Mihaylov, an investor and fan of Koychev's work. He knew of Koychev's dream to build a habitable sculpture and commissioned him to do it. The sculptor made 1:10 scale models and all the measurements were calculated. A year later a sculpture appeared on the site.

The first floor is made of stone, like a traditional Bulgarian house, while the second and third are of wood daubed with clay and straw and whitewashed on the inside.

"I had wanted to make a sculpture house for a long time. Not a kind of Cameroonian hut, but a work of plastic art in which you can live." That Koychev was successful is clear from the silence with which architects greeted his project – they must have literally been rendered speechless. Who could blame them: the sculptor dealt perfectly with all the architectural problems.

The construction is primitive but strong. The transparent canopy shields the house from rain and snow and allows in the sun's rays at the same time. The house is comfortable with its wooden flooring, PVC windows and doors, and boasts a fireplace, a heating system, electricity and running water.

All the materials used for the interior are natural – even the bathtub, the washbasins and the toilet are made from wood. The contours of the house fit in organically with the surrounding scenery and the design and construction are completely in keeping with modern requirements.