Two tasks: reduce ignition sources and limit consequences
A faulty electrical connection can be an ignition source. Whether this develops into a larger roof fire also depends on roof materials, module arrangement, fire loads and spread paths. Active or preventive measures and passive protective layers therefore work together.
VdS 3145 covers the design, installation and operation of PV systems. The FRISSBE/ZAG guideline adds a view of fire development with elevated PV systems on flat roofs. Both perspectives are useful for early design. [1] [2]
Survey the roof build-up before the module area is fixed
Record the supporting structure, vapour control layer, insulation, waterproofing and existing ballast. Add age, moisture condition, connections, rooflights and drainage. From this it follows whether the roof should be retained, repaired or re-waterproofed.
EPS, PIR and mineral wool differ in material behaviour. That alone, however, does not yield a finished protection concept. Fixing, insulation facing, layer thicknesses and fire side are also relevant. The installation position of the mineral protective layer is therefore chosen together with the existing condition.
Plan PV layout, clearances and details together
Modules change the radiation and airflow pattern above the roof. Distance to the roof surface, tilt and row arrangement influence the scenario. Rooflights, smoke and heat exhaust ventilation, fire compartments and maintenance routes need space in the layout plan. [2]
Blanket clearances from someone else's project are not a sufficient basis. What governs are the requirements of the specific building, the applicable regulations and coordination with the responsible parties. A plan agreed early saves later re-layout.
Use mineral materials in the right position
For new construction and re-waterproofing, DEK as a stiff cover board and SHEET as a thin fibre-reinforced layer beneath the roof membrane come into consideration. If the waterproofing remains, WEER focuses on a weather-resistant board on the roof surface beneath PV. VLOEI stands for the route of a cement-bound compound applied on site.
For full-surface fabric solutions, PYROFAB SOL White can also be included in the comparison as a further material option. The specific task and the associated documents remain decisive; a textile layer and a load-distributing cover board have different functions.
Order operation and repairability as part of the package
The roof must remain accessible after installation. Inspection of electrical connections, checking of the roof waterproofing and clear outlets fulfil different tasks. A mineral layer does not make these checks unnecessary.
Define how defective modules, damaged membrane seams and concealed outlets can be reached. Document the materials actually installed and the responsibility for later changes. This keeps the concept usable beyond the construction phase.
Compare the roof survey, PV layout and insurer requirements side by side. This reveals missing clearances, unknown roof layers and required measures before ordering.