The invention relates to a building concept wherein locations of rooms such as bathrooms and kitchens can be easily changed during the lifespan of the building. These rooms may be positioned in several locations almost everywhere in the building and the building may be easily remodeled during its lifespan. The invention is based on providing at least one space part that comprises a floor(43) defining the area of the space part and at least one length of non-load bearing wall (27) bordering the perimeter of the floor (43) and at least one load bearing vertical duct element (11) having at least one vertical cover wall that can be at least partially opened in order to provide access to the inside of the element(11).