What is hot work? Everyone thinks of a torch, welding or spark production but thermal transfer can start a fire.
Although not hot work in this case, thermal transfer took place here when the furnace in the mechanical room beyond malfunctioned. The high limit switch did not shut down the furnace and the studs and lathe INSIDE the wall combusted. The horse hair plaster on the furnace side and drywall on the unit side were still in good shape (other than fire department accessing the area). This unit was installed with less than an inch to the wall behind it. Pay attention to your minimum clearances. Secure a permit and inspections. This was a lodging house filled with students. Luckily they were on break and the university was diligent in their patrols of the unoccupied building and notified the fire department.
Thanks for reading.