I was in the garage the other day and wondered why the temperature was so unbearable. I did a little research and discovered that the garage door can be a big factor in overall garage temperature. But there is definitely more to consider.
Insulate your garage door if the cost-benefit analysis says it's worth the time and money. You can warm or cool the garage without insulation. Which you choose depends on costs and benefits.
There are many cost-effective garage door insulation solutions, but you have to consider the status of the garage walls, windows, ceiling, floor, and doors to decide if garage door insulation is worth your while.
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Have Realistic Goals for Your Garage's Temperature Range
The good news is that insulating your garage door is a relatively easy and cost-effective way to help make your garage more comfortable.
The bad news is that it isn’t going to instantly transform your intemperate, cement-floored, car storage place into an awesome recreation area.
Insulating the door can help take the edge off.
It will make your garage a bit more habitable.
But even these modest goals are dependent on lots of variables.
In the end, it’s up to you to whether spending $60 on a space heater will go further than using the same money on door insulation.
It doesn’t take a lot of deep thought, but taking a little bit of time to clarify what you want goes a long way.
The Insulation R-Value Does Not Tell the Whole Story
R-Value is the one number you can use to compare the insulating effects of various products.
The higher the number, the more insulating power.
Sounds simple right? It is.
But there is more to the story.
R-Values are calculated in a lab under ideal conditions.
Your garage door (or walls or house or whatever) is far from ideal.
Let’s use a regular wall as an example.
Your wall has studs.
In between those studs is insulation.
Let's say that insulation has an R-Value of R13.
Does your whole wall have that R13 value? No.
The studs have their own R-Value of R6.
So the whole wall has a combined R-Value based on a mathematical formula combining the R-Values of all the different components and the total surface area of the wall.
Add in windows and any small gaps or unsealed seams etc.
And you get the picture.
Far from ideal conditions.
Even then, the average temperature and our level of comfort aren’t always the same.
We’ve all experienced the discomfort of a cold draft coming in from somewhere even though the house is an otherwise comfortable temperature.
Concrete garage floors can be cold even when the garage door is insulated.
Why Do Garages Lose Heat or Gain Heat?
Heat goes into and out of your garage or house in three ways:
- Radiation is the transfer of energy from one object to another through the atmosphere. Think of the sun beating down on a roof. The roof receives energy without touching the source of that energy (the sun).
- Convection is the movement of lower-density warm air upward, and higher-density cool air downward. Heat rises into the garage attic, creating a current that pulls cool air in from outside. “Infiltration” is a form of convection that occurs when cool air comes in through a gap in the building materials.
- Conduction is a molecular heat transfer when objects touch. The sun heats the roof through radiation. The shingles sit on the wood, which sits over the attic. Conduction transfers the warmth from the shingles to the wood and air.
R-Value measures only a material’s resistance to conduction.
These tests are done under idealized laboratory conditions.
The upshot is heat, cold, wind and moisture might reduce your garage door insulation's effectiveness.
Weak Links in the Garage Climate System
Air will get in through any openings, seams, and gaps.
Stopping this as much as possible is your first line of defense.
You can spend an hour or two doing a great job insulating the door but if there’s a nice big gap somewhere you might as well be crying into the ocean to make it saltier for all the good you’ve done.
Before you buy insulation for the garage door, check the door and windows for gaps.
If the air is whistling through the gaps, you must fix this problem before installing insulation.
You can insulate the garage doors, but before you do, think about the rest of the garage's insulation status.
If your garage walls are not insulated, then insulating the garage door might not offer much temperature control.
Learn more about sealing gaps with weather stripping below.
Are your garage walls insulated? If yes, then insulate the garage door, too. But if not, then you're at a decision point.
Uninsulated walls will transfer out a ton of heat.
An insulated garage door will control temperature a bit, but not necessarily enough to justify the cost and time involved.
You can use fiberglass, rock wool, or blown-in cellulose insulation material.
Learn the differences in my article: Garage Insulation Choices: Batt, Spray, or Blown? as well as Is Batt or Rigid Foam a Better Choice for Garage Insulation?
Does your garage have an attic? Heat rises.
When it does, it causes a convection current.
The current sucks colder air into the garage.
Insulating the ceiling is a tougher job if you're working over your head.
Owens Corning suggests using foam board and fiberglass batting.
Are your garage windows sealed up? Between window glass and frame air gaps, windows are also a big place where heat is lost.
Get a plastic sheet kit for each garage window. Get the Owens Corning sheet on Amazon.
Clean the window frame before applying the plastic.
If you don't clean the frame first, the sheet might fail to hold.
The kits come with tape. Attach the sheet to the window edges using the tape.
Then use a hair dryer to shrink the sheet.
As the sheet shrinks, it becomes a barrier between cold air and your garage.
Measure Hot and Cold Spots in the Garage
Diagnosis is really the first step in solving the garage temperature problem.
Unless you can see the sunshine through a faulty wall, you might not be able to see sources of heat and cold you need to fix.
Use a thermal leak detector to find hot or cold spots in the garage.
The results will tell you where you need to shore up or insulate to get the garage temperature under control.
Consider the Black and Decker TLD100 Thermal Leak Detector. This very useful device lets you measure temperatures and temperature differences on surfaces and objects.
Is the switch plate colder than the rest of the wall? Is the garage door colder than the other wall? A thermal detector can help you decide which problems require attention.
Seal Gaps with Weather Stripping
Old weather stripping around the door should be removed and replaced.
It wears down with time, making it ineffective.
Use vinyl or foam weather stripping to seal gaps on the door edges.
Search for “vinyl garage door top and sides seal.”
Install the side seals before addressing the top of the door.
Let the top seal drape over the sides.
This ensures any water dripping down from the top runs along the outside of the side stripe.
Without the overlap, water might collect behind the side seals.
Now seal the bottom of the garage doors.
If your garage door has a channel at the bottom, get a complete kit that runs the rubber seal through this channel, like this DGSL Seal on Amazon:
You might need to tighten or replace the door track that keeps the seal in place. It's easier to get a rubber seal that sits on the garage floor, under the door.
But if you do get the kind of garage door seal that inserts into the bottom track, there are a few things you can to do make installation easier.
After tightening the track, ensure the channels are clear. It will make your life a lot easier to have two people do this.
If you soak the new rubber in a container of water and a little dish soap it will make the rubber slide in the channels more easily.
The other kind of bottom strip is simply a piece of rubber stripping that gets nailed to the bottom of the door.
You can replace that with the Universal Aluminum and Rubber Garage Door Bottom seal available on Amazon here.
You will need a drill with a screwdriver bit to get the self-tapping screws to go through the aluminum.
With just a little pressure they should go right through.
Another and easier option is to get a seal that sits on the garage floor. Instructions for this are in my article The Best Garage Door Seal which details how to install a Universal Garage Door Seal that you put on the garage floor:
If you have a door that is manufactured by Amarr, Arm-R-Lite, CHI, Clopay, DBCI, Deldon, Gadco, Martin, Raynor, Richard Wilcox, or Safeway then you should get this one from Amazon, made by Clopay that is designed to fit doors made by those manufacturers.
It has a very soft rubber that won't lose its shape in very cold weather and will fill in the gaps caused by uneven flooring.
Should You Seal Between Garage Door Sections?
The most common garage door is a sectional door.
When you raise the door, the door breaks up into sections that roll along a “J track” on either side and up along the ceiling.
When open, the door hangs horizontally above the garage.
The gaps between these hinged sections that allow the door to move are another opportunity for air to make its way into your garage.
You will either have tongue and groove or flat-edged garage door sections.
With the door closed, check for light coming through where the sections meet.
Caution! Don't weather strip garage door sections that aren't letting in light.
Weather stripping can add stress to the hinges and damage the door.
To seal sectional gaps, use foam weather stripping with adhesive on one side.
You’ll need a ladder and a friend.
Lock the door in place for each section.
Carefully stick the weather stripping tape to the top of the lower section.
Do this for each section.
Be sure to check your work.
Pick a nice sunny day, go into your garage with the doors closed, let your eyes adjust, and look for light peaking through any cracks.
Adding Heat in the Winter and A/C in the Summer
If you turned off the heat in your house in the middle of winter, how long would it take before the house was cold? Even if the house was well-insulated? Insulation will only go so far.
Without any additional sources of heating or cooling, the temperature inside will eventually approach that of the outside.
I would go so far as to say that if your garage is significantly warmer in the winter or cooler in the summer, it could be a sign that you are wasting energy.
If your garage is not insulated and you add electric heating or cooling, most of the energy will be wasted.
A fan and radiant heater might work for very short-term use.
But you want to insulate a garage before adding any heating or air conditioning that will be on for hours at a time.
Several degrees can make a huge difference in terms of comfort.
The less temperature variation you have in your garage, the easier it will be to cool and heat your house.
Any room that shares a wall or floor with the garage is potentially sharing its temperature control with the garage.
Is Your Garage Stealing Your Home's Heat or Air Conditioning?
If you are trying to save on energy, insulate the wall that the house shares with the garage.
If your house is keeping the garage warm (or cool), you have a big problem.
If you use fiberglass insulation on the house-garage wall, install it backward.
That is, put the fuzzy side toward the garage, and the paper/foil vapor barrier toward the house.
The same applies to a living area over the garage.
Install the paper side toward the upstairs floor.
The paper side should always face the living environment.
When insulating the rest of the garage walls, install the paper barrier toward the inside of the garage.
Garages usually have an entrance door to the house.
Put weather stripping along the edge where the door meets the door frame. If the door feels cold, you might consider getting an insulated door Sometimes the builder will skimp on the interior door leading to the garage.
An insulated garage door to the interior of the house will help lower your energy bill.
Use your thermal leak detector on conduits such as electrical outlets, and openings for pipes or wires.
To insulate outlets, look for “socket sealers,” “wall plate insulation” or “electrical socket covers.” To insulate pipe conduits, look for “pipe insulation tubing” or “fiberglass pipe wrap.”
You Might Have to Rebalance the Door
Your garage door has springs that are calibrated to the weight of your door.
They are designed to make the door easy to open.
When properly balanced, your door should stay put when half open.
It should not shoot up or fall down. Garage doors are delicately balanced.
Even a small change in weight can upset them.
After insulating the door, use the thermal detector along the door edges. The Black & Decker on Amazon will help you decide whether to insulate the door
If the door is off balance, it will still allow air in from the outside.
Garage door springs are under heavy tension.
If you don't know exactly what you're doing, hire a professional to balance the door.
It's even more important if you have a motorized garage door opener.
The motors are designed for balanced doors.
Unbalanced doors can add weight that will wear out the door movement motor.
What About Garage Door Insulation Kits?
There is a great case to be made for buying garage door insulation kits like the ones in our garage insulation kit reviews.
Manufacturers of these kits offer everything you'd buy individually.
Kits come with all the proper fasteners to attach the insulation properly.
The main complaint from customers is that the in some kits, the adhesive doesn’t stick well. The door must be clean before using the adhesive.
Extreme heat or cold will inhibit the adhesive’s initial effect.
So it is best to install insulation kits using adhesive on a mild day when the door is neither too hot nor too cold.
Garage Door Insulation Types
- Measuring the Owens Corning garage door insulation batting
There are three basic types of insulation for garage doors:
- Batt insulation is the thick, fluffy fiberglass or rock wool that comes in rolls. Rock wool is more expensive but has much better fire retarding properties than fiberglass. The thick and fluffy nature of batt insulation is what makes this insulation work. If your garage door can accept batt insulation great, if you have to compress it, then don't use batt insulation. Compressed batt insulation doesn't work. Here is a great choice for batt insulation on Amazon. It's an Owens Corning garage door insulation kit.
- Foam board insulation is a stiff, rigid panel that resembles Styrofoam. It has a lower R-value than batt insulation.It can be used on wooden and metal doors. Only use foil-faced rigid panels. Unfaced polystyrene is a fire hazard.
- Reflective insulation is a flexible insulating material surrounded by shiny foil. It helps keep garages cool in the summer.It can be combined with other insulation types. If your main concern is keeping your garage cool, check out this reflective insulation option on Amazon.
Garage Door Side Channels
The other thing to keep in mind is that for the most part manufacturers assume you have a metal door with channels on either side where you can insert the insulation.
If you have a wooden door you will need to use some form of tape or adhesive to secure the insulation.
These channels are a perfect fit for the fiberglass sheets in the Owens Corning garage door insulation kits like these from Amazon.
You can also fit the solid foam core insulation into them. Some wooden doors have recessed panels that can fit the foam core insulation found in rigid foam garage door insulation kits.
You will need to measure and cut the foam core to size.
You can then add another panel on top of that across the whole section.
For wooden doors, you should consider using the IMP SmartGARAGE Reflective Garage Door Insulation Kit (linked to here at Amazon).
This kit does not require a metal door like the others and is very thin and light.
You can use it in conjunction with rigid foam panels if you like. If you are buying a newer house, ask if the garage door is insulated.
Many of the newer garage doors have an insulating foam core already.
Rigid Foam Panel Insulation Caution!
An important note about rigid foam panels.
You absolutely must make sure that they are fire rated and have either a foil or vinyl facing.
Foam board by itself is extremely flammable.
That is another good case for buying a garage door insulation kit.
You may want to check your local building codes and your home-owners policy just to triple check.
Under no circumstances should you just buy random foam panels and use that as insulation.
Use Radiant Insulation for Heat Reduction
The final option is radiant insulation like the IMP SmartGARAGE (Amazon link) insulation kit mentioned above.
Radiant insulation is shiny and flexible and is very good at keeping the heat from the sun out of the garage.
It comes in sheets or panels and you can tape or glue it to the door directly.
Radiant insulation can be paired with rigid foam core insulation.
Install the radiant insulation closest to the door and then attach the foam over that.
Make sure you use double-sided tape that is foam safe.
This is important as some adhesives will melt the foam.
This is another good reason to use vinyl or foil-faced panels.
Match Your Expectations to Your Climate
If you live in a climate that often goes to single or triple digits (Fahrenheit), the weather might be more powerful than your garage insulation.
Unless you renovate the garage into an interior living space, your insulation efforts will fall short of your home's ability to retain heat and cooling.
If you have a newer home in an extreme temperature area, your garage door might already be insulated.
The garage door is but one piece of the garage.
Use reflective insulation in very hot areas.
Use thicker insulation in cooler areas.
In both climates, remember that air gaps, windows, walls, and ceilings are as important as your garage door.
The Garage Door Insulation Cost vs. Expected Savings
Insulating the garage door can help reduce noise coming in from outside.
It will also help reduce the noise your neighbors hear coming from your garage.
Sealing and insulating can also help prevent fumes and noises from getting into the house.
Garages are by their nature not the cleanest of environments.
Your car emits fumes.
You store toxic pesticides.
An untreated garage floor (not treated with a densifier or sealer) generates dust.
Bugs can come in the large garage door opening.
Builders generally use cheaper windows in the garage than the rest of the house.
The door leading from the garage to the house might be insecure and poorly insulated.
When you take the insulating and sealing steps mentioned in this article, you're also addressing the noise, fumes, and security issues as well.
The garage door insulation by itself is a small but essential step in protecting your house from noise, fumes, dust, bugs and intruders!
People Also Ask
Should I insulate my garage door if I don't plan to insulate the rest of the garage? Yes, if your garage door faces a very hot sun or very cold north wind. Otherwise, it's probably not going to change much without insulating the walls and windows too.
Should I insulate my garage door if I don't have a heat or air conditioning source? Yes, if you're going to insulate and seal the windows and walls.
Which garage door insulation kit should I buy? The Owens-Corning fiberglass kit is meant for metal doors. You can use foam core and reflective garage door insulation kits on both metals and on wood garage doors.
End Notes
Buildings and Heat Transfer, by Alfred Moser, Thermopedia, retrieved from http://www.thermopedia.com/content/603/, November 2018
Buyer’s Guide to Insulation: Rigid Foam, by Martin Holladay, Fine Homebuilding, retrieved from https://www.finehomebuilding.com/2012/01/24/buyers-guide-to-insulation-rigid-foam, November 2018
How To Insulate Your Garage – Garage Insulation Project, Uncredited, How To Home Insulation, retrieved from http://howtohomeinsulation.com/insulation_projects_garage_insulation.html, November 2018
Top 4 Signs Your Garage Door is Unbalance, Uncredited, My New Door, retrieved from https://www.mynewdoor.com/blog-posts/top-signs-your-garage-door-is-unbalanced/, November 2018
