The first, fastest, cheapest and, easiest place to begin insulating a garage, is the garage door. Most doors are made of aluminum which, as a metal, heats and cools according to the weather.
Garage door insulating KITS are easy to find and fast to install. I used one of our kits on my garage door, a very cheap door I might add, with huge air spaces between the horizontal panels, and it has made a major difference in the amount of heat leaking into the interior of the home.
In extreme outside temperatures (Texas mind you), there would be a 23 – 25-degree difference and on milder days the difference was much less but still between 12 – 18 degrees (like this morning, 51 outside and 63/64 in the garage).
This photo shows a good quality garage door, where there is no light coming in through the hinges (must be a few quality levels higher than mine that is for sure). If your door is like mine, placing the bubble foil inside the panels as the photo above, is not enough.
This photo shows how to install and attach the bubble to a portion of the hinge, starting your install from the bottom panel going up. Each panel above the other will be long enough to hang over the remaining top portion of the hinge, to cover that metal and prevent radiant heat from entering.
I did a very, let us just say, inexperienced install, but it works and the way I covered the hinges works, and that is the beauty of radiant barrier, it does not ever have to be perfect to function. Regardless of my fabulous install and, cheap garage door with air leaking around the sides like the Titanic, the product and concept work like a charm. The garage is so much cooler and the horrible heat leaking into the house my first year in a Texas summer, is no longer an issue. Such a simple KISS fix for some creature comfort.
The next area to address when insulating a garage, is the attic because it is such a huge energy drain which, equates to money. For a reasonably fast fix, add insulation to the garage ceiling. This can be done either in the attic laying perforated radiant barrier down horizontally or, inside the garage using single bubble foil attached to furring strips. For this application, the foil/white bubble will be perfect so the foil is facing the attic and the white side is facing down in the garage maintaining a nice white ceiling.
Lastly, the walls should be addressed. If it is an unfinished garage, just studs and siding, that is a super easy fix because you can install radiant barrier in a multi-layer system avoiding thermal insulation or, if you prefer, radiant barrier next to the siding then fiberglass batt. The radiant barrier will be installed on furring strips next to the siding and then fiberglass may be added or, you can install a second layer of radiant barrier bubble with 1 inch between the first layer and then cover with sheetrock.
If the garage is finished? Install furring strips on top of the sheetrock, then attach single bubble foil/white to those with the foil side to the sheetrock and white facing into the garage.
Insulating these three areas will make an immense difference in a garage and if attached, all that hot radiant heat will not be heating up the walls to the interior of the home.
We have read various opinions and articles stating it is “pointless to insulate a garage” if not going to mechanically heat or cool the garage and, we disagree. Why? Because in the Sun Belt area of the United States, the garage transmits huge amounts of heat into the home and interior walls. This increases AC use and means the AC will still be working overtime after sundown to mitigate all that day heat slowly releasing from the building materials into the night.
Radiant barrier will increase creature comfort inside the home, decrease energy consumption and save wear and tear on the AC unit. The whole point of insulating a garage, is to STOP radiant heat from entering and heating the building materials. Thermal insulation in a Sun Belt garage is not necessary with the new multi-layer system. Take it a step farther and break the Thermal Bridge by using three layers of bubble, two between the studs and the final layer, attached to spacers on the studs covering the studs incorporating the heat from the studs into the radiant barrier envelope. Now you can really work in that garage on projects.
Cold Climate garages can benefit greatly with radiant barrier when it is installed closest to the heat source (interior of the garage) which, will prevent heat from leaking out through thermal insulation and then to the cladding.
If you have a garage window, during the summer months, add a Temptrol Curtain using small tension rods fitting inside the window frame with the reflective side facing out. These can be removed once the hot months are gone. If you want to keep the heat in, and light from the window is not important, use bubble foil tacked up on the sides of the window frame leaving an air space against the window or create a removable “winter” window frame which, will insulate some and keep the heat in. Another option is to add a window insert, used in historic homes from manufacturers such as Indow, and then add a Temptrol curtain on tension rods. The window insert will insulate from leaks and the Temptrol curtain can be turned each season, summer reflective side out, winter, reflective side in. So easy and, it DOES work.
The goal with insulation is to Keep it Simple Stupid or for those of you who prefer the altered version, Keep it Sweet and Simple. The original came from the US Navy in 1960. Most systems work best if they are kept simple rather than made complicated. Therefore, simplicity should be a key goal in design and unnecessary complexity should be avoided. Radiant barrier helps to keep it simple because it works no matter how perfect or imperfect an installation job was.