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

Paroc Air
PAROC® Air™ ventilated roofs increase the safety and soundness of flat roofs. Through grooves in the insulation, PAROC Air ventilates and dries moisture very quickly and provides an effective and simple solution to avoid moisture in structures.

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.

Paroc Air solution - a unique way of ventilating flat roofs

Number  The movement of the wind forces air up the grooves towards the wider ridge channel.
Number 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. 
Number 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. 
Number  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.
Number 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.  
Number Cut holes in the board underneath the roof vents.  
Number 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. 
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Moisture in buildings 
may cause:

- bad indoor air qualities that affect the occupants' health and comfort
- deterioration of building materials and structures

Ventilated Roof research report

VTT research report on critical performance parameters in ventilated roofs (pdf, size 1 Mb) >>

The following products are used for the solution PAROC Air.

The roof slabs and boards are non-combustible stone wool insulation for use as a load bearing thermal insulation layer of existing and new flat roofs. The roof insulation slab is developed to provide sustainable, hard and fire safe bedding for rigid top insulation layers as well as insulating the bearing layer in renovation sites. The suitable roof slab for flat roof will be chosen based on the product's mechanical properties and thermal conductivity.

The compressive stress of the roof board PAROC ROB 80 is 80kPa, which means that the slab can carry a 8000 kg/m2 load during installation and use.
The compressive stress of PAROC ROS 30g is 30 kPa, which means that the slab can carry a 3000  kg/m2 load during installation and use. This means that it is suitable for normal level loads. The ventilation grooves in the surface of the board are installed upwards during the installation stage. These grooves enable the constant drying of the whole roof construction. The compressive stress of PAROC ROS 30 is 30 kPa, which means that the slab can carry a 3000  kg/m2 load during installation and use. This means that it is suitable for normal level loads.
The roof ventilator is placed at the ridge or at the valleys above the across cut grooves in the insulation. Can also be delivered with bended bottom plate to follow the slope of the roof.