Insulating an unfinished, unheated space such as a garage or storage area requires special considerations to ensure optimal insulation. Closed-cell spray foam insulation is a popular option, but it can be costly. Additionally, some types of insulation are specifically designed to protect against radiation. An air barrier should also be installed to prevent cold garage air from short-circuiting the insulation below the subfloor.
If the air distribution is in the attic, consider insulating the beams to move the distribution to the conditioned space. The optimal insulation materials for foundations and location vary depending on the climate, so it is best to consult a local insulation professional when building a new home. Insulation panels are a great choice for insulating a detached garage as they have some of the highest R-values per inch of any type of insulation. Expanded Polystyrene (EPS) is popular because it is versatile and has the best R-value per dollar than any other insulating plate. It is also popular for modernizing the insulation of old houses and for insulating detached garage roofs. To maximize efficiency, it is important to insulate walls, roof, and garage door with the highest possible R-value.
However, if air gaps remain unfilled, heat will still be wasted. The approximate costs of insulating a detached garage open 24 hours a day with R-13 and R-19 insulation materials can be found in the following table. Prefabricated garages with insulated walls, windows, and floors typically cost 15% to 20% more than an uninsulated garage; insulating only the floor will add about 10% to the cost. Loose-fill insulation is usually less expensive to install than block insulation and provides better coverage when properly installed.
