Insulating an attached garage has some special considerations that you must address differently then a unattached garage.
Insulating attached garage roof.
The most important issue is that attached garages must have a system in place to keep carbon monoxide co from a running vehicle inside the garage from filtering through the walls and ceiling into the house.
However if you have a cathedral style garage roof you will need a scaffolding to get into the upper areas of the roof.
Keep in mind that the structural metal ribbing of garage doors is an excellent conductor of heat and this typically doesn t get insulated.
I wrote a big article discussing whether you should insulate your garage.
Regulate your garage s temperature all year by installing insulation.
Be sure to count the spaces above doors and windows.
If your garage is attached to your house you will notice a big difference in your home s temperature as well.
One of the best methods you can use if you want to regulate the temperature of your garage is to insulate the garage roof.
Don t insulate your garage walls and ceiling without insulating the big garage door too.
If you have a flat garage roof and an attic above you can install the garage insulation from below using a standard ladder.
You can buy insulation kits for standard metal garage doors or you can cut pieces of rigid foam insulation to fit each door panel section.