PAROC® Air™ - a Unique Way of Ventilating Flat Roofs

Moisture in structures is a major risk factor that you want to avoid. If moisture stays in the structure for an extended period of time, mildew may form in the material that is in contact with stone wool. A ventilated flat roof reduces moisture already at the construction phase and buildings can be brought into use earlier since problems related to moisture can be avoided.

This is how PAROC® Air™ works in practice

The ventilated solution uses natural draught to quickly transport moisture away from the flat roof. To protect from outer moisture leakage, in the form of rain and snow, use a normal roof membrane. To protect against moisture from the inside air being collected and built in to the structure, place the vapour barrier around 50 mm up in the insulation, which is protected itself by the under layer slab. The tightening of the roof structure maintains the balance of inside and outside temperature, moisture and pressure.

	The movement of the wind forces air up the grooves towards the wider ridge channel.
	Use a 50 mm stone wool slab to protects the vapour barrier and safeguards its effectiveness.
	The vapour barrier consists of a plastic sheet or equal, which prevents rising warm air from condensing on the membrane. Ensure the vapour barrier and junctions with the rest of the structure are free from leaks. Seal all joints and ensure there is an overlap by of at least 200 mm, otherwise this can lead to a "chimney effect" in which moist air is drawn up and freezes inside the structure in winter. The vapour barrier also ensures that the ventilation system works better throughout the building, since it eliminates draughts.

	A grooved stone wool with high vapour permeability carries moist air along grooves to vents. The slab is supplied with grooves cut in it that are 20 mm deep, 30 mm wide and have a c/c of 200 mm. Transverse channels are then cut across the grooves at intersections with items such as roof windows and fire hatches.
	Ensure that the wider ridge channel, which is cut by hand, is 100 mm wide and 20 mm deep. This channel connects the grooves that run up the slop to the roof vents.
	Use a 20 mm stone wool board to keep the air in the grooves around 5 degrees warmer than the outside air. Use this board to form the base for the outer membrane.
	Cut holes in the board underneath the roof vents.
	Roof vents made of metal or plastic finally lead the moist air outside. Install the roof vents at 6–8 m intervals along the ridge and at 10–12 m intervals in valleys. Ensure they have a diameter of 100 mm and a height of around 400 mm.