Single or Double walled Stainless?

[deejayoh]

Double wall for sure. 8" is probably overkill for a 36" oven. I think the FB 36" ovens use 6" (check me on this) - but you only need to go high enough to have adequate clearance beyond whatever you are using for roofing

[MeBeMarc3]

Should I buy single wall (uninsulated) or double wall (insulated) stainless for my flue? How tall should I go with an 8" flue? it's a 36" oven. Thanks in advance for taking the time to discuss.
Marc