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.
Insulating garage ceiling vapor barrier.
I m considering insulating and drywalling my garage which already has insulated garage doors.
After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one.
If you re adding new garage doors be sure to install insulated options.
If you live in a hot humid climate.
My main goal is to keep it from getting much below freezing during the winter.
In reality insulation merely slows the transfer of heat through the insulated barrier wall ceiling floor etc.
A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
I want to insulate the ceiling in my garage.
When the house was built 10 years ago the walls attached to the house were done and the ceiling was drywalled fire code.
In hot humid climates attics should not be vented and vapor.
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.
This garage is located in the north cascades 2000 elevation in washington state with a typical yearly temperature range of 0f 105f.
If you live in a cold climate place the vapor barrier between the interior of your home and the insulation.
Not every wall does.
Vapor barriers keep the air moisture in your house from condensing in the insulated cavities.
Whether your vapor barrier is a facing or a film it must be placed on the warm in winter side of the wall.