Speakingof residential chimney, there are several types-single-wall, double-wall,stainless steel 304, stainless steel 430, galvanized stee, etc. We've had many people callasking for stove pipe and after talking to them, we have found what they reallywanted was chimney. Stovepipe only goes from your appliance to the ceiling orwall, that's where chimney takes over. You need the insulating power of Class-Astainless steel chimney to go through the wall or ceiling all the way up pastthe roof. Besides it being to code, it is the safest thing to do.
Eventhough "grandpa used to do it that way", sticking a single wall pipeout of a window and up to the roof is very dangerous. Codes call for an18" clearance to combustibles for single wall pipe, and for good reason.Even though that single wall pipe may work fine for a while, it is what canhappen and will happen that brings those clearances into existence in the codebook.
Alwayskeep in mind that all codes are set up for you to be safe in a "worse casescenario". Worse case scenario for a chimney is a chimney fire. Thatsingle wall pipe turns cherry red during a chimney fire that burns around 2000- 2500degrees F. Anything combustible within 16 inches of that glowing redsingle wall pipe can catch on fire, which would be your house.
Using single wallpipe also increases the chance for chimney fire because it collects much morecreosote than does an insulated chimney. The colder the chimney, the morecreosote adheres to it. You may think you are getting away cheap by usingsingle wall pipe, but as many have found out, losing your home, or even afamily member, due to using single wall pipe is a lot more costly than theright type of chimney.
Class-A stainlesssteel chimney has clearances down to 2" to combustibles. Which means thateven during a chimney fire, combustibles that are 2" or more away from thechimney will be safe.