it is in the weather all the time hot & cold the last roof & gutter sealant didn't last very long, is a flexable mastic better or silicone
Roof and Gutter Silicone silicone will be by far the best sealant for the job. The success and longevity of the repair will all depend on the surface preparation. The surfaces need to be clean and free of all dirt, dust, mould and old sealants. In particular if a different type of sealant has previously been used. Old sealant can usually be removed using a sharp knife such as a Stanley knife or similar retractable blade trimming knife. There are also special tools which might be able to be used to help cut the old sealant out. Once the joints are cleaned out give everything a brush clean (An old toothbrush or small wire brush is good for this) and wipe over with a rag soaked in a little Turps or Metho then wipe dry. When applying the sealant ensure it is forced into the joint and not just smeared over the top. If applied correctly Roof & Gutter Sealant will remain flexible and last for many many years.