Insulating garage doors

I live in Ontario, Canada which makes winter mod season in the garage a little cold. I've just bought a 4000W 240V construction heater to use when I'm out in the garage but am also going to insulate the garage doors (the garage is part of the house so the walls and ceiling are already insulated but my bedroom is directly above and more insulation will make the wife happy).

I'm leaning towards the foil radiant insulation over the foam panels but does anyone have any ideas, opinions, suggestions for this?

As insulation benefits in both hot and cold climes, what I did was purchase a garage door with the panels already insulated. Cheating, I suppose ... wasn't expensive.

I would lean toward a rigid foam board. Depending on the door design, how they open, etc. Keep in mind that adding weight to an overhead door, may necessitate replacement of the springs to get proper balance. The springs aren't expensive either. And totally worth it to have a pro do it.

I used to install doors.
The biggest mistake people make is when they paint or add anything to the door, it makes it heavier.
This will require adjustments to the springs.

The second biggest and sometimes fatal mistake is them trying to adjust the springs themselves.

After you do whatever you do to increase the insulation, please call a door company to come and adjust it.
My two cents....

If you have the punched metal sectional doors a 1 1/2" rigid foam board with foil skin should will fit into the reccess. To get it to stay in you could cut it tight and use a interferance fit and I believe they would stay in. If not you could use foil tape from HVAC supplier that would finish it rather well. Dont use duct tape it will fail sooner than later. DRSWADE is spot on with the danger of playing with that giant striped spring hanging out overhead. You will be adding enough weight with the isulation panels that an adjustment will be in your future.
I am fairly confidant the springs you have in place now will do the trick.
one thing nice about heat is it rises faster than it heads sideways so you will be helping the master while you slave away in the garage.