You might find it beneficial to install garage door insulation of you often stay in the garage for car maintenance and repair.
Insulation is better than to buy a new door because it is cheaper and easier.
You should insulate your garage if it attached to your house because it can serve as a port for unwanted heat and cold in entering and leaving the house.
Most people will simply buy garage door insulation kit to do the job.
There are kits for wood, steel, and aluminum door and casing.
It is also available in various height and length depending on your garage size.
Aside from kits, you can use self spray foam insulation to ensure that there will be no leaks and holes in the rubber sealant of your door.
You can also cut it in various shapes and sizes to better insulate the sides of your door, or use it in conjunction with weather stripping.
There are other steps in garage door insulation that you should do to effectively shut off unwanted heat or cold from your garage.
You can also place insulation materials to your floor and roof similar with what you did in the house.
Whether you buy a kit or apply other insulation material in the garage, make sure that you will consider its R value and insulation rating to maximize its effect and ensure that you will be comfortable in both hot and cold seasons.
You might also want to consider sound-proof insulation to keep car repair noise from getting to the house.