Soil Pipe Through Polycarbonate Roof

Hi all i need to make a watertight seal around a soil pipe and downpipe that is running thru a polycarbonate conservatory roof.
Soil pipe through polycarbonate roof. Polycarbonate roof and is of the lean to type. At the stage were weve got the polycarbonate sheets in and we need to apply some flashing to seal the top but i have a soil pipe running down through the roof and i would just like to know the proper way of sealing around a soil pipe hope someone can help thanks. Gibraltar building products 1 4 in. How to seal around a soil pipe coming through a polycarbonate roof.
Aluminum base vent pipe flashing with adjustable rubber collar in black. I have seen 2 options from other photographs 1 cut the wall plate in 2 and fit either side of the soil pipe. There is a soil pipe on the wall where i want to fit my wall plate. Flashband has been used along the width of the roof but around the pipes is very badly done cement fillets that are breaking up.
Free next day delivery available free collection in 5 minutes. Easily mouldable to suite any roof profile.