Hello. There is flexible (nylon?) wire could ducting in my loft that is leaking. There are several tiny splits in it. Over a period of time, this has damaged the ceiling of the bathroom below. This ducting goes from a soil pipe, up through the loft and out through the roof. The soil pipe is 110mm and the flexible ducting has been slipped over the end and ties with a zip tie. I want to replace the 3 meters of flexible ducting. But I cannot find anything this diameter. The house was built in 2000. Are pipes a different size now? So the first question is, where can I buy 3 meters of 110mm flexible ducting? Second question is, assuming I can find some ducting, how do I waterproof the join? A zip tie does not work. Should I cover the end of the pipe with a mastic of some sort before slipping the ducting over? (American web sites offer a product called Ductseal - a white solution that can be painted onto the pipe before adding the ducting. I have not seen anything like that on UK sites.) Many thanks.