Like most garages, yours is probably built on a concrete slab. The walls might be insulated, especially walls shared with the house.
It might contain appliances and equipment like a washing machine, water heater, or water softener. Make sure chemicals and fuels are properly sealed and stored at least 3 feet away from these.
If the door has an automatic opener, it should have two safety features: auto-reverse sensors and a manual release cord.
Replace garage door sensor: $110 – $200
Replace door opener: $225 – $525
Repair door: $150 – $340
Replace door: $600 – $2,750