Soil Pipe Through Roof

After climbing into the loft to install a tv ariel i ve noticed that the soil stack from the ensuite vents through the tiled roof but the main bathroom pipe stops about 2 feet above the joists insulation in the loft space with some sort of polystyrene cap on it.
Soil pipe through roof. What is the minimum requirement for a soil vent above the window or roof the minimum a soil pipe should be above an opening area is 100mm. Aluminium sheet fits neatly underneath the roof tiles to blend in with the roof profile while the rubber adaptor provides a watertight seal around the outside of the soil pipe to stop water entering the house through the soil stack. Oatey 1 1 2 in to 3 in x 15 in plastic vent and pipe flashing. Easily mouldable to suite any roof profile.
For pricing and availability. Oatey retro master roof flashing 1 4 in to 4 in x 8 in epdm rubber vent and pipe flashing. Gibraltar building products 1 4 in. It s common practice in many states to reduce the soil stack to 2 inches and extend that 2 inch pipe through the roof.
It must extend at least 6 inches above the roofline.