I have a unique 1965 home that has a large Central room with a wood ceiling that the roof board directly affix to (no gap to hold insulation or create an air barrier). I recently had the tar and gravel roof replaced with rubber membrane, after the fact they casually mentioned that there had been insulation under the tar and gravel but never said anything else about it.
Since the replacement my main room has been considerably warmer than the rest of the house (traditional insulation) and I’ve just found out that no insulation was added or replaced when my roof was replaced meaning there is just two layers of wood and the rubber membrane between me and the outside world.
Is this a normal practice with rubber roofs? Do they have some kind of amazing natural insulation? I live in an area that gets well below freezing in the winter and I can only imagine all my heat escaping through the roof.