I have a large room over my garage. As expected it's hot in there compared to the rest of the upstairs. Does insulating the garage door really help anything? I can't see it really keeping the garage that much cooler.

An insulated garage door is worth it. In part just because it cuts down on the solar gain. Then it's just about the good air sealing around the door.

Insulated doors hold up better against the wind, and cut down on the outside noise as well.

the sun shines directly on my white uninsulated garage door and there is definite heat build up because of it.

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Originally posted by doublesharp:
the sun shines directly on my white uninsulated garage door and there is definite heat build up because of it.

hits my insulated one pretty hard in the evening

my insulated garage will get warm, esp this time of year, but my master bedroom is above it with no issues

Is every wall insulated? Is the ceiling insulated? I would make sure those are done first.

Yes insulating the door is worth the effort, look at any heated shop it'll be insulated.

Our last home was like that. We had a large bonus room over the garage. Always hot in Summer and cold in Winter, even after fixing the air leaks that existed. The sun didn't even hit the garage door. Turned out to be our HVAC. The guy that replaced the old unit said that our single system supplied the whole house at once. The bonus room and our bedroom were on the back end of the system which meant that they relied on the back pressure in the system for their airflow. Well, air follows the path of least resistance so the rooms on the other side of the house got all the airflow, our bedroom got less and the bonus room got the least. The only way to remedy the situation would have been to install dampers in the ducts and go with a zoned system (like we have in our current house) or install a second unit just for the bonus room which would have been a huge expense for such a small space. Even installing dampers and another thermostat was more than we wanted to spend at the time.

Long story short, check your HVAC flow and efficiency. Insulating the garage door may do nothing.

Like others have said, it does make a difference. It also depends on how you insulate it. There are kits at hardware stores but you will also need some backing for the kits as the pieces of insulation can fall out move. If you replace your door,if that is an option, with an insulated door, it will be the best option although expensive.