u/ppshard

Building a small sauna (6'x8') with a flat interior ceiling and a 12 degree shed roof above it. The space between the flat ceiling and the sloped roof acts as a ventilated attic cavity - air enters at the eave through bug mesh and exits at the ridge gap under the flashing.

Insulation (R-19 mineral wool) is in the rafters between the flat ceiling.

A few questions:

1. Do I need insulation at both the flat ceiling level AND in the rafters, or is flat ceiling insulation alone sufficient?
2. Does this assembly make sense as a cold roof, or am I missing something?
3. For the wood-burning heater chimney - do I need two separate pass-through flanges (one at the flat ceiling, one at the roof penetration), or is one enough?

PS the grey part is aluminum vapor barrier

Working on a new smaller sauna plan set. 6x8 interior, flat ceiling at 7'8", bench: 12" bottom step, 18" middle, 18" top at 48" from floor, 44" clearance to ceiling. Freestanding island step to keep the aisle clear.

26.5" aisle to the heater - too tight? Assuming a heat shield but heater brand TBD. Any other thoughts on the layout?

Sharing another angle of the sauna I designed and the wall/roof junction detail. Ventilated rainscreen cladding, mineral wool insulation, aluminum vapor barrier on the warm side. Happy to answer any questions on the assembly logic.

Hi! Just wondering if I missed something in these details. Any advice appreciated! I'm mainly concerned if I show the barriers ending in the right places.