Application on the roof

The sub-structure framework is to be designed and executed according to structural requirements (related to building and location).

Provide necessary information like batten spacing and detailing (e.g. hip and ridge detail, positioning of cable channel etc.) to the carpenter before the projects starts and check correctness of course.

The substrate must be carried out according to applicable standards and adapted to local conditions.

Recommendation for full formwork:

Board width: 80–160 mm
Board thickness: at least 24 mm (or in accordance with national standards)
Wood humidity: max. 20%

Recommendation wood-based panel (according to EN 14964):

Material thickness: min. 22 mm

In the case of single-skin, non-insulated roof structures, a sub-roof must comply with the requirements of national regulations (sub-roof standards), and a bituminous separation layer is required as a minimum. Structured underlay is not required due to the corrosion resistance of aluminium. PREFA does not recommend the use of structured underlay. When using thicker separation layers, the use of longer screws is necessary.

When using wood-based panels as an installation substrate for PREFA roof coverings, the choice of thickness, the mounting to the wood-based material and the intended use as a metal roof substrate must be agreed with the manufacturer or dealer of the wood-based panels.

When using wood-based panels, a separation layer separation layer is required.

OSB sheets as a substrate are special purpose solutions and should be planned as such.

Note

PREFA does not recommend the use of OSB sheets as a substrate for metal roofing with or without a separation layer.

Due to the necessary cable routing, the timber supporting substrate must be made according to the following details. The number and position of cable ducts are defined by PREFA’s Product Technology department and displayed in the PV installation plan.

1 Solar roof panel
2 Bitumen separation layer
3 Sealing tape
4 String and connecting cables

5 Cable duct (flashing)
6 Fully supported substrate (at least 24 mm)
7 Construction wood
8 rafters

1 Solar roof panel
2 Bitumen separation layer
3 Sealing tape
4 String and connecting cables

5 Cable duct (flashing)
6 Fully supported substrate (at least 24 mm)
7 Construction wood
8 rafters

1 Solar roof panel
2 Bitumen separation layer
3 Sealing tape
4 String and connecting cables
5 Cable duct (flashing)
6 Fully supported substrate (at least 24 mm)

7 counter battens
8 Nail sealing tape (as required)
9 Breathable roof underlay
10 rafters
11 Insulation material

1 Solar roof panel
2 Bitumen separation layer
3 Sealing tape
4 String and connecting cables
5 Cable duct (flashing)
6 Fully supported substrate (at least 24 mm)

7 counter battens
8 Nail sealing tape (as required)
9 Breathable roof underlay
10 rafters
11 Insulation material

Roof penetrations or entrances into the interior of the building break through several layers of components and thus require the cooperation of several trades (roofers/tinsmiths, carpenters and electricians).

All measures are to be carried out in accordance with the construction schedule.

Roof penetrations must be made professionally and must not impair the suitability or function of the sub-roof.

Adhesive sleeves, such as those used in the PREFA solar hatch, can be such a solution.

Cable bushing via ridge for single-skin roof construction (Fig. 1)
Cable bushing via ridge for double-shell roof construction (Fig. 2)
Cable bushing in the surface for double-shell roof construction (Fig. 3)

Application on the roof

Sub-structure framework and structural information

fully boarded substrate

Sheets made of wood-based materials

Cable channel

Roof penetration