Advantages in the physics relating to construction of a solid roof

Besides the prime task of providing protection against rain and weather, a roof has to fulfill the physical requirements relating to construction of protecting the building underneath against the influences of heat, wind, noise and moisture, providing a shield to withstand high temperatures in summer and be a firewall as well. For the traditional rafter roof, this means additional functional layers in the roof structure for e.g. heat insulation, a second water-conducting layer (undercovering), back-ventilation and a vapor barrier, compared to the originally simple structure of rafters and roofing material. Seen from this point of view, roofs have an often more complicated structure in comparison with other constructional components and care is called for to avoid damage in execution of the work. And this even more so the less the workers know about the functions of the other layers from the other craftsmen. Against this background, investigations were undertaken in pilo t projects to determine whether it is possible to resolve the requirements relating to construction in a better way by new types of structures for roofs. Alternatives to the traditional and well-known sloped roofs with rafters were therefore investigated in a study [1] to determine their physical properties relating to construction. Promising here were the benefits of concrete and aerated concrete for roofs towards the thermal behavior in summer, the impermeability to air and noise protection. Starting from these positive aspects in the approach, a roof module was developed on the basis of a sub-structure made of concrete. Two variants were realized: An aerated-concrete and a reinforced-concrete precast unit with a large-format prefabricated insulating element [2], [3]. Three variants of the design for the roof construction (and the traditional rafter roof for comparison purposes) were constructed in collaboration with industrial partners, and the tests carried out on three roofs of an apartment hou