The roof ventilation

Below is an example that emphasizes the importance of adequate ventilation obtained through a ventilated under-ridge, under-tile ventilation and a ventilated eaves line.

• Location: Milan - average summer solar irradiation 270 W / m2 approx.

• Through energy in the attic without ventilation (laying with mortar curbs), approx. 9 W / m2.

• Through-energy in the attic with ventilation chamber of approx. 3 cm, approx. 3 W / m
  2, or 65% less.

• Under the roof: the air section between the roof and the insulation must be greater than 20 mm in height and not less than 200 cm2 / m at the length of the pitch. With an air opening section of 30 - 40 mm, greater benefit is obtained and ventilation is effective.
  
  

A noticeable ventilation effect can be seen through the overlapping of the tiles.

• Microventilation: free air chamber section <2 cm / m.

• Ventilation

• Free air chamber section> 2 cm / m.
  

Increases in ventilation thickness do not bring additional benefits. The use of mortar along the eaves and / or ridge line renders the ventilation null.

The more the roof is inclined, the more pronounced the thermal lift will be. In flat roofs the pure upward effect is nil.

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