You are correct: the vapour barrier goes on the inside, closest to the warm room. This prevents the moist air in the room from condensing within the insulation,

You are correct: the vapour barrier goes on the inside, closest to the warm room. This prevents the moist air in the room from condensing within the insulation, accumulating water and causing rot and mold. My late father-in-law, who worked in construction, says they found out the hard way in the 1940's when fiberglass insulation was first installed, without vapour barrier. Within a few years, entire walls would just collapse, the studs and framing having rotted like cheese. And I never use a block heater North Dakota is South of Calgary.