I am finishing (insulating, heating, installing receptacles) the room above my garage, to be a music studio. The space was roughed in, mostly insulated, and drywalled by the prior owner. However, one end wall, which was installed around an air handler for one of our HVAC systems, was somehow left un-insulated. Insulating this wall will be a real challenge (largely inaccessible and roof-line space), but that's a topic for another thread. Of interest here is the pair of access doors, used once per year for servicing the air handler. They are currently un-insulated barn doors, filling a rough opening 50"W x 73"H. My first thought was to replace them with insulated double doors, but considering they really only need to be opened to service the air handler (less than once per year), and the considering the cost of custom double doors... I'm thinking of building or buying an insulated wall panel instead. The idea would be that this wall panel could be removed or re-installed with minimal effort, hopefully making use of the existing rough opening, although I could re-frame as necessary while I have things torn up right now. Any advice? Can one buy such an insulated wall panel, or will I need to build? Another idea may be to leave the existing doors, and then just install some insulated plug behind them, which could be pulled out when access to the HVAC system is required.