Installing a new but old wood stove which recommends a chimney height of 6" x 16'. My predicted setup will be 5' of black single wall pipe followed by 6' of double wall stainless steel. The 6' of DW meets the 3/2/10 guideline so I'm good on code. However, I'll be about 5' short (5' + 6' = 11') of the 16' recommend height. Can I install 5' of black single wall pipe on top of the double wall stainless pipe? I live in Rock Springs, WY which is high desert country. Dry, snow would never reach the black pipe, rains infrequently and very little. I work in metal fabrication so making a secure connection between the two isn't an issue. I'm looking more for reasons why not to have single wall on top of the double. Basically trying to avoid the additionally $140 to continue with double wall vs. the $15 it'll cost with single. Thanks!