Installation guidelines for pitched roofs

Air and vapour barrier

Fit PAROC eXtra insulation from the upper side of the roof. Start heating only after the air and vapour barrier has been installed. This prevents water vapour from being unnecessarily transported through the structure and possibly condensing against the outer roof. Carefully fit the liner so as to avoid leakages. Overlap the vapour barrier seams by about 200 mm and fasten them to fully seal the structure. If the floor structure is made from a sealed, full-coverage concrete plate, the air and vapour barrier is not needed.

Properly ventilate the attic

The outer roof and attic area need proper ventilation so that warm, moist air that finds its way into the attic can be led away. Otherwise there will be a risk of moisture and rot damage. Ventilate all along the eaves, where there should be an air gap that is at least 50 mm high.


Lay the insulation slabs in two or more layers, without gaps or cracks with adjacent components. Lead the ventilation air up over the insulation using a wind diverter. This means that the insulation does not lie directly against the outer roof. Moist air that condenses against the outer roof is led away. The distance from the insulation to the upper edge of the wind diverter must be at least 100 mm. As a rule, no wind protection is needed on the upper layer of insulation slabs since the movement of air is so small that it does not affect the functioning of the insulation.

Insulating roofs with PAROC BLT blowing wool

For roof insulation, loose blown wool is an alternative method. The material is applied using a blowing unit that can be used at heights of up to 40 m. (Note: Blowing wool installation should be carried out by specially trained contractors only. Contact your nearest Paroc office for further information.)

Insulating pitched roofs with PAROC eXtra slabs

The roof covering is water-repellent and relatively vapour tight. The roof should be well ventilated in order to avoid high levels of moisture accumulation. For ventilation, use air gaps at the eaves as well as at the ridging and valves in the gable ends.

Air and vapour barrier

Fit the air/vapour barrier with great care! You want optimum air tightness so that moist air does not come through and condense against the outer roof.


When insulating sloping roofs, the dimensions of the roof framework often determine the insulation thickness. Increase the thickness with secondary studs. Fit the insulation in one or more layers with staggered joins. There must be openings in the eaves and the ridge to promote good air circulation. In a sloping roof, the air gap should be at least 50 mm.