So, You Want to… Insulate a Garage Door


Insulating your garage door can help keep your workshop comfortable this winter and throughout the year. Here’s what you need to know when undertaking this DIY project.

As the weather turns cooler, now is the perfect time to protect your garage against the upcoming cold weather, especially if you have a home workshop in your garage. Metal garage doors can block strong winds, but they do little to maintain a comfortable temperature.

If you’re not ready to invest over a thousand dollars in a new, pre-insulated door, consider outfitting the garage door you have. We’ve gathered all the information you need to learn how to successfully insulate your garage door, plus some tips to help you get the most out of the project.

Benefits of insulated garage doors

Adding insulation to the interior channels of your door can keep your garage an average of 10-12°C in the winter and up to 20°C in the summer. Insulated garage doors also reduce the transmission of sound. Not only will you not hear traffic noise from the street when you are working in your garage, but your neighbors will not hear your son practicing his band in the garage.

Garage door insulation kits

The easiest way to insulate your garage door is to use a kit that contains vinyl or foil finish rods or foil finish rigid foam boards. Garage door insulation kits, such as the Reach Barrier Garage Door Insulation Kit, start at about $50. Some kits are more expensive but include all the supplies you need: adhesive, tape, cutting knife, gloves and possibly a dust mask. This is all in addition to the garage door insulation panels, which are, of course, pre-cut to standard sizes.

But the main advantage of using an insulation kit is that it comes with specially designed retaining pins. These pins, made of lightweight plastic or metal, are fitted with a plate that sticks to the back of the garage door channel and helps to hold the rigid foam or batts in place. This stabilizes the insulation so that it doesn’t fall onto the car when the door is opened. If you choose not to use garage insulation kits, there are other ways to hold the insulation in place.

R-value and garage door insulation

A typical garage door is made of metal and offers little protection from outdoor temperatures. Insulation can help, but not all types of insulation are the best insulation for garage doors.

Insulation materials are classified according to their ability to reduce the transfer of heat and cold. The higher the thermal resistance or “R-value” of an insulation material, the better it will stop the transfer of heat and cold. Some hints.

  • The thicker the insulation material, the higher the R-value.
  • The thicker the insulation material, the higher the R-value. The R-value of a watt mold decreases when it is compressed or wetted.
  • To increase the overall thermal resistance, consider adding insulation to the bare walls as well as to the doors.
  • Insulation with a high R-value will not significantly reduce heat transfer if airflow enters the garage and cold air flows in.

Choosing the Right Type of Garage Door Insulation for Your Home

The main types of insulation used for garage doors are batt and rigid foam. It is recommended that you learn about both types of insulation to determine which one is best for your garage door. That being said, most people choose rigid foam because any coil that is not in the garage door insulation kit is likely to be too thick for the door.

How to insulate your garage door

Passing on an insulation kit? Most DIYers choose foil-faced rigid foam board insulation panels that you measure and cut with a sharp cutting knife or table saw to fit the inside grooves of your garage door.

There are three main types of foam board that can be used as garage door insulation as long as they are foil faced and fire rated. It is flammable and produces dangerous gases when it burns. In fact, its use may violate local building codes.

  • Expanded Polystyrene (EPS). Available in a variety of panel sizes, rigid or slightly flexible expanded polystyrene is used on the inside of garage doors. It resists moisture and heat and has an R-value of about 4.6% per inch of thickness. It is available in a variety of panel sizes, with or without a surface.
  • Extruded Polystyrene (XPS). Extruded polystyrene is not difficult to identify. It comes in blue, pink, green and other colors of foam sheets. It provides an insulation value of R-5 per inch of thickness. It is available in faceted and faceless garage door insulation panels.
  • Polyisocyanurate (ISO). Polyisocyanurate foam board is manufactured by spraying a liquid onto a substrate and then laminating the substrate all over (usually with aluminum foil). Polystyrene is commonly used for roofing, but is also suitable for insulating garage doors. It has high insulation properties at R-5.8 per inch of thickness.

Choose a foam board that is slightly thinner than the thickness of the door’s internal access enclosure. For example, a standard garage door channel is about 1¾ inches deep, so you will want to cut it out of a 1½-inch thick Styrofoam board.

Although it may vary, most garage door channels have a “lip” that holds the board in place in the channel. However, rigid foam boards can still be a bit rickety if they don’t fit snugly. Before inserting the boards, apply a little foam safety adhesive to the back of the garage door channel to help it stay in place.

If necessary, you can use Styrofoam to seal the gaps on either side of the board, but remember that a small amount of Styrofoam will do the trick. Check the label on the adhesive or foam sprayer to make sure it is compatible with the foam board you are using – some adhesives will melt the foam board.