I purchased two sheets of tin 2 x 1m, a roll of 5cm thick fire insulation and 3m of flue. Most of the flue inside the cabin would not be insulated as the hot flue will provide additional heat. I wrapped the insulation around about two thirds of the flue and stitched the edges of the insulation together with thin wire. I then wrapped a piece of tin around the insulation and cut the ends of the tin and bent them over to hold it in place (as you can see in the picture below).
The minimum requirement of insulation is 5cms where the flue goes through the timber roof but I decided to double this by adding another layer of insulation at the point where the flue would go through the roof. Around this insulation I put another piece of tin
I cut a hole through the cabin roof
and inserted the flue through the hole
On the roof I bent over the edges of the outer piece of tin and screw the edges to the roof to hold the flue in place, as you can see below
I shaped a piece of tin to go over the flue and cover the area of roof I had cut out, applied a bitumen sealant and screwed the to the roof the prevent rain getting in. I also made a tin cap to go over the flue to prevent rain getting in. While I was doing this work, the temperature was -30 degrees and fingers kept freezing to the metal. On one occasion I made the mistake of holding a screw between my lips while I worked and of course my lips froze to it and I had to wait for the screw to warm before I could remove it!!
I screwed another sheet of tin to the timber wall behind the uninsulated flue, to prevent the wall getting too hot and the work was then complete.