LucasNewMalden

Hello In 2021 I bought DEFRA approved stove and paid OFTEC engineer to install in my summer house. https://www.hpmmag.com/renewables/oftec-launches-solid-fuel-registration-service Kinston (Surrey) council building control approved the process and I have certificate. But this certificate covers entire property - not only summer house hence we want to move it inside home. Question: how would you prevent flat roof from leaking after putting flue pipe thought it? Should I use this https://www.fluedirect.co.uk/twin-single-wall-commercial-flue/12-601-residential-low-temperature-black-epdm-masterflash-3337.html