Penetrating mounting systems fix directly to purlins, rafters, or structural decks through the roof cladding, providing a positive load path for dead load, wind uplift, and lateral forces. They are standard on corrugated metal, standing seam, and tiled roofs. The structural engineer confirms that the fixing substrate can carry the transferred forces and that fixing spacings are appropriate for the applied loads.
Penetrating mounts require careful waterproofing at each fixing point to maintain the roof envelope. For membrane roofs where penetrations are necessary, specialist flashing boots or pitched flashings must be used, and the structural capacity of the deck at fixing locations must be confirmed. Structural surveys identify fixing substrate suitability as a core assessment task.