The double wall pipe is used if the gap is less than 18.
Diy double wall stove pipe.
Your worries about the durability of galvanized steel.
Darwin invented the foam mate which is a machine that creates a nice thick foam the consistency of shaving cream.
Single and double wall single wall pipes are used when there s a gap of at least 18 between the combustibles and the chimney system.
This foam can be added to concreate to make.
The double wall allows a clearance of 6 from the wall and 8 from the ceiling.
Once the gauge of the pipe is determined next step is to measure the length of the sheet required to make a pipe from the stove s exhaust to the chimney flue.
A major issue with these is a loss of heat or having it misdirected.
The homemade triple wall chimney pipe you are considering could work for a while in principle but i strongly advise against your trying it.
In this measurement reduce the length at least by two inches as the 90 degree elbow is about 8 inches tall.
The pipe should fit the outlet or exhaust of your wood burning stove.