Should I Insulate an Unheated Garage Before Drywall Is Installed?

Function

• Insulating your garage blocks air leaks and moderates air temperature. Insulation helps keep warm air from escaping from the house and limits cold air drafts in an unheated garage. Insulating the garage keeps it cooler in summer and warmer in winter by limiting heat exchange through the walls. This moderates the garage temperature and cushions the house against outside temperature extremes. Additionally, installing drywall over the insulation provides a finished wall for garage storage and projects in the garage.

Installation

• For most homeowners, batt or blanket insulation, available in rolls or in precut sections to fit between wall studs, can be installed quickly before drywall is put up. Fiberglass insulation, fire- and mold-resistant, is typically covered with a facing or vapor barrier that is stiff and holds the batt insulation in place. Precut insulation strips fit snugly between the wall studs, though they can be stapled to the wall for more stability. The insulation vapor barrier faces the inside of the garage. Drywall is installed over the insulation and anchored to the studs.

Vapor Barrier

• A vapor barrier protects your insulation and walls against excess moisture. The vapor barrier blocks moisture from accumulating in the insulation and condensing on the cold exterior garage walls. Either choose insulation with a vapor barrier, or install a vapor barrier between the unprotected insulation and the drywall. One simple method is stapling a thick sheet of clear polyethylene plastic over the insulation pads before installing the drywall. The plastic sheeting is stapled to the studs and blocks moisture. Use clear plastic so that the studs are visible when you install the drywall.

Tips

• Insulating the garage makes the space quieter because the insulation and drywall absorb noise. For added benefits, add rigid foam insulation panels to steel garage door panels. Do not block the regular ventilation grids or openings in the walls, as some air exchange is necessary for fresh air and to reduce carbon monoxide buildup around appliances such as gas water heaters. Due to the insulation and drywall, the garage can be more easily heated for work tasks or garage chores. As an added bonus, the car in an insulated garage does not feel so cold on an early morning commute.