Ventilated roof, how it works and what are its advantages. Extensive and intensive ventilated roof, cold roof and other technologies in comparison.
The covers have the function of protecting the internal environment from atmospheric agents and external temperatures. To guarantee this fundamental function, there are different types of covers, we are talking aboutcold roof(ventilated insulated cover orventilated roof) and warm roof (non-ventilated insulated cover).
There are also non-insulated ventilated roofs, in this case, no insulating layer is used, however the ventilation reduces the effects of heating due to summer solar radiation.
The ventilated insulated roof includes both a layerheat-insulating, is a ventilation layer. The ventilation layer is interposed between the insulating layer and the overcover. To give you a diagram of the layers of aventilated roof we list the layers that make up this particular insulating cover:
- load-bearing element or cover support
Generally it is concrete cast on site or mixed masonry, prefabricated panels, wooden panels, metal sheets ...
- Vapor barrier
It is not always decided to insert the vapor seal layer. Strongly recommended in contexts with high humidity levels.
- Thermal insulation
Thermal insulation panels, rolls ...
- Ventilation space
This layer is obtained by creating a gap of constant thickness interposed between the roofing elements and the underlying layer.
The overcover is an integrated element of the ventilation layer. Generally built in wood.
- Waterproof mantle
- Ancillary works
we mean finishes, walkable covering, tiles ...
The cold roof orinsulated ventilated roofit is mainly used in the case of wooden roofs, pitched roofs and for residential buildings. On the contrary, the warm roof is generally used in industrial construction. The non-insulated ventilated roof, again, it is mainly used in those structures that are typically used in summer or in agricultural structures.
The warm roof provides the same layers seen forinsulated ventilated roof, what is missing is the wooden overcover and ventilation space.
The characteristics of the insulated ventilated roof, what the law says
According to UNI 9460, the flow section for the cavities really effective in reducing the heat flow in summer climate, in the case of usual slopes in Italy (30-35%) and usual pitch length (up to 7 m), is at least 550 cmq net for each meter of pitch width.
Thanks to the provisions of the UNI 9460 standard, it becomes easier to establish the thickness of the ventilation layer such as to guarantee greater living comfort in summer. Proper sizing of the ventilation layer is essential to ensure i advantages related to the system.
Ventilated roof, how it works and what are the advantages
THE advantages must be sought in greater thermal insulation. Thanks to the layer ofventilation, the water vapor produced in the house is expelled outside the roof, eliminating the problem of condensation. A house with ventilated rooffinds himself differentadvantages, for example, a significant reduction in the possibility of mold and humidity problems on the walls, not to mention a well insulated roof.
How does it work?
The natural gap that separates the roof covering from the insulating layer, causes the so-calledupward convective motions, that is of the currents that subtract most of the heat that would otherwise be transmitted to the underlying layers. Thanks to the upward convective motions, steam and humidity tend to disperse without compromising the thermal insulation power of the other layers of the roof.
The upward convective motions are activated when the external air penetrates the interspace through the cracks that are located at the level of the eaves. The current is generated at this point until it comes out of the ridge through a vent element, the point indicated with the number 9 in the figure above.
Thanks to this operating mechanism, the ventilated space protects the house from humidity in winter (leaving the other layers of the roof dry), while in summer it maximizes the efficiency of the thermal insulation layer by enhancing the insulating power of the roof.