Question: I'm installing a chimney for a wood boiler. For the sections of the pipe that aren't in contact with anything and far away from any combustible surface, can I just use single-wall pipe (and just use insulated pipe for the thimble and pipe that passes thru the ceiling and the roof? Also, in the old days we had things like asbestos paper to put on things to make them non-combustible. What kind of insulation like that is available now? Answer: If the pipe is inside the same room as the boiler, then you can use single wall pipe to hook from the stove to the chimney. This pipe cannot pass thru walls or floors. It should be at least 18" from combustibles. This can be reduced to 9" with the use of a heat shield on the pipe or wall...24 gage sheet metal with 1" spacers from the wall or pipe will do. Sheet metal..or wonderboard (durarock) cement board can be used as wall protectors when installed according to instructions.