Defects and damage to roofs arise as a result of design errors, Implementing, maintenance or materials, as well as as a result of natural aging of the covering material.

Coated profiled sheets are an ideal covering material, enabling quick and relatively cheap replacement of roofing material or installation of a new covering over the old roofing felt. Due to the low weight, the profiled sheet allows the use of the existing structure without the need to rebuild it. Roofs before renovation may be characterized by deformation of planes. Small unevenness of the slope is corrected with wooden wedges and soffit slats. For cavities larger than 10 cm and with weakening of the existing structure it is necessary to support the rafters from the bottom.

Ventilated two-part roofs are a beneficial solution due to the physics of the building – prevent overheating of rooms on the last floor and to a lesser extent than full roofs are exposed to damage during operation.
An interesting possibility of renovation of solid roofs is the superstructure of the old roof with a supporting structure forming a ventilated two-part roof. The supporting structure is made above the old roof cover of the full roof from the system of cold-formed steel profiles. Selection of appropriate profiles is made on the basis of structural calculations. C and Z profiles and hat profiles are used as standard. Profiles are designed for the weight load of roofing and snow. The method of fixing the new structure depends on the size of the designed slopes and the wind force affecting them.

For larger project projects, terrace roofs, green roofs and bipartite roofs are often combined with each other. Such projects require detailed and careful development of details of architectural and construction solutions, taking into account correct and reliable water protection and ventilation of roof roofs. In particular, this applies to the details of the roof connections with the walls and with the attics, connections between different types of roofs, Dilatation, roof drain solutions, balustrade fasteners, skylight bases, Stairs, hatches, e.t.c.
Roofs above utility rooms intended for the stay of people should be designed as ventilated two-part roofs. This solution is more advantageous in terms of building physics and more effectively prevents the building from cooling down in the winter and overheating in the summer.