Hello there Allen,
Well spotted.... I have a very small wood burner in my shed, similar to the type you find on say a narrow boat.
I have a few sections of twin walled flue which pass through the side of the shed. I packed some rock wool (fire retardant material) all round the pipe where it exits the wall.
I also have some offcuts of another fire retardant board type material around the wood burner and against the sides of the shed.
I never load the fire too much just a few small offcuts and in 10 mins I have a lovely warm shed. I cramp it down then and top up when needed.
I also open the window when it gets too hot!
There is no doubt that my setup would not pass the appropriate building regulations, but as it is not a dwelling they do not apply.
It was fairly easy to install and is a useful way of getting rid of offcuts sawdust etc...
It is also nice just to sit in the shed, with the fire going, reading my latest copy of F & C or Woodworker, smoking my pipe and relaxing.
I'm sure there are better methods of heating a workshop....Oil filed radiators for one, but you just can't beat the romance of a wood burner.
If I get a chance I will post some pics. If you have any specific questions please fire away (forgive the pun).
Happy Christmas Allen, all the best. Esc.