The bedroom over the garage needed slippers even when the hallway felt fine. We had adjusted its register, added a rug and debated a larger heater. None of that explained what separated the room from the cold space underneath.
I asked for the floor and garage ceiling to be included in the assessment, rather than discussing only the air coming from the register.
The room has an exposed boundary below
Source: Natural Resources Canada: insulating walls and attached garages
Natural Resources Canada's insulation guidance addresses rooms over unheated garages. Air sealing and insulation at the separation matter for heat loss, and the separation also helps keep garage fumes out of the home.
That makes an improvised opening into the garage a poor comfort fix. House heating supply and return ducts must not be extended into the garage as a shortcut.
The assembly may need professional inspection to establish insulation coverage, air leakage and appropriate repair details. Existing ceiling finishes and fire protection must be considered when planning access.
Assess the heating delivery too
We recorded the room's temperature alongside the hallway, outdoor conditions and door position. We kept the supply and return paths unobstructed and asked for the delivered airflow to be checked.
A cold floor, insufficient airflow and a weak return path can coexist. Repairing one does not prove the others are adequate.
For any proposed additional heating, I wanted the room's load and the available electrical or HVAC capacity assessed first. The proposal also needed to say how the new control would interact with the existing system.
The rug stayed because we liked it. The repair discussion became more concrete once it covered the actual floor assembly, the room's air delivery and the safe separation from the garage.
I no longer described the problem as 'upstairs is cold.' It was one room with a particular boundary underneath, and that detail changed what needed checking.
