If you live in a hot humid climate.
Insulating garage ceiling vapor barrier.
Vapor barriers keep the air moisture in your house from condensing in the insulated cavities.
Not every wall does.
After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.
Whether your vapor barrier is a facing or a film it must be placed on the warm in winter side of the wall.
I want to insulate the ceiling in my garage.
There is a school of that maintains that an unheated garage that is attached to the house may get some benefit from insulating the walls and ceilings of the garage since it theoretically offers an additional thermal buffer.
My main goal is to keep it from getting much below freezing during the winter.
If you live in a cold climate place the vapor barrier between the interior of your home and the insulation.
If you re using old uninsulated doors pick up a retrofit kit that add insulating panels.
I m considering insulating and drywalling my garage which already has insulated garage doors.
You can forego the plastic and use a vapor retarder kraft faced insulation or latex ceiling paint in all other climates except hot humid or hot dry climates.
A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
This garage is located in the north cascades 2000 elevation in washington state with a typical yearly temperature range of 0f 105f.
In hot humid climates attics should not be vented and vapor.
When the house was built 10 years ago the walls attached to the house were done and the ceiling was drywalled fire code.
Install as directed typically cutting to fit and using a staple gun to attach the vapor barrier to the studs.