Choosing The Best DIY Garage Insulation Materials

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Choosing the best insu­la­tion mate­rial for your do-it-yourself garage insu­la­tion project.

As you know, one of the least energy effi­cient areas of our homes is the garage, specif­i­cally the garage door. Most garage doors are made of aluminum, steel or wood and are usually installed unin­su­lated. The typical double garage door is 7 ft. x 16 ft. That’s over 100 sq. ft. of unin­su­lated space. Whether you have a single or double car garage, your unin­su­lated garage door is allowing heat in during the summer and letting heat escape during the winter.

I’ll bet you’ve prob­ably felt how hot your garage door gets in the summer and how cold it is in the winter. Well this is the sign that it’s time to correct the problem and start reducing your energy bills.

And if your water heater is in the garage, it’s effi­ciency is affected too. The colder it is in the garage the longer the water heater has to stay on to keep the water temper­a­ture constant — which means a higher energy bill.

Since there are several different insu­lating mate­rials to choose from, it’s not surprising that this is one of the most often asked ques­tions I receive;

“Which insu­la­tion mate­rial should I use to insu­late my garage and water heater?”

Fortu­nately I have a simple and inex­pen­sive answer as well as a couple of tips to help make your do-it-yourself insu­la­tion project a breeze.

So here we go.

Types of Insu­la­tion Materials

First let me explain the different kinds of insu­la­tion mate­rials avail­able to you.

Spray Foam Insulation

Two part spray foam is very effec­tive but you’ll have to buy a kit ( about $350 for a double garage door ) or hire a profes­sional to perform the work. That makes this mate­rial the most expen­sive choice.

Rigid Foam Insulation

Although Rigid foam is less expen­sive than spray foam, it’s also a bit less effec­tive due to a lower the R-value — which leads me to what I believe is the best mate­rial choice for this do it your­self home insu­la­tion project.

Prodex Insu­la­tion

ProdexProdex insu­la­tion, commonly known as a radiant barrier, is the DIYers best choice for these types of insu­la­tion projects because it’s inex­pen­sive, easy to install, and very effec­tive. It also has a built-in bonus I’ll tell you about later.

Prodex Total insu­la­tion is only 1/4 inch thick and made of a closed cell foam core covered on both sides with tear resis­tant foil. This amazing radiant barrier reflects 97% of the heat. It also offers an excel­lent R-value and is about half the cost of rigid insulation

For about $120 you can easily and simply insu­late your garage door and water heater, and imme­di­ately begin saving energy.

DIY Tip Be sure to order Prodex Total as it has the more effi­cient closed cell foam core.

Tools and Materials

Prodex Total is easy to install with these simple tools;

Stanley 25 ft Measuring Tape

Measuring Tape

Straight Edge Carpenters Level

Straight Edge Level

Husky 82068 Utility Knife

Utility Knife

Silicone Caulk

Sili­cone Caulk

Foil Tape

Foil Tape

Garage Door Insulation

Cut the insu­la­tion to size and apply it to each garage door section with sili­cone adhe­sive. Use foil tape to repair any tears or to cover seams.
(Before) Garage Door Insulation

DIY Tip: Cut the insu­la­tion on a piece of plywood to keep from dulling the blade of your utility knife.

(After) Garage Door Insulation

DIY Tip: Be sure to posi­tion the insu­la­tion quickly as the sili­cone will set fairly fast.

You may have noticed the extra bonus I was talking about from the photos — the highly reflec­tive quality of the insu­la­tion will instantly brighten your garage. Nice.

Insu­lating the Water Heater

Since you’re insu­lating your garage door, go ahead and insu­late your water heater too. Remember, even if your water heater is in the house, you can save money by insu­lating the tank. Use the same radiant barrier insu­la­tion to insu­late your water heater.

Insulated Water Heater

DIY Tip: Make cut-outs for the pilot and ther­mo­stat access. Use a bit of duct tape to secure those pieces so you can easily access them later.

[sws_blue_box box_size=“549”]PLEASE be sure to read, under­stand and follow all safety precau­tions and proce­dures when working with, near, or around any gas or elec­tric water heater, or for that matter any appli­ance. You can also refer to my Insu­la­tion Do’s and Don’ts article for more tips. [/sws_blue_box]

So, when you’re ready to under­take your do-it-yourself garage insu­la­tion project and you’re faced with selecting from multiple insu­la­tion mate­rials, I highly recom­mend Prodex Insu­la­tion. It’s a great radiant barrier and can be easily purchased from They also have a garage door insu­la­tion kit here.

[sws_grey_box box_size=“549”]Save even more money with a DIY Solar Heater Kit[/sws_grey_box]

If you have ques­tions about your DIY projects, just ask your personal DIY consul­tant. I’m here to help you succeed with speed.

Garage Door Openers

If you don’t see what you’re looking for, just click through for more options.

8500 Lift­Master Elite Series Wall Mount Garage Door Opener
8500 LiftMaster Elite Series Wall Mount Garage Door Opener $329.90
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Wayne Dalton Torque master I drive Garage door opener
Wayne Dalton Torque master I drive Garage door opener $400.00
Time Remaining: 2d 19h 32m

8500 Lift­Master Elite Series Wall Mount Garage Door Opener UPC 012381850013
8500 LiftMaster Elite Series Wall Mount Garage Door Opener UPC 012381850013 $333.00
Time Remaining: 13d 16h 5m
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Thanks again,

Your DIY Answer Guy.
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DIY Help Category Heating & Air
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The Prodex may be ok to keep heat out under bright sunlight but since it relies on radiation it wouldn't work as well to keep heat in. I did a comparison of R-value for different products. This one looks to have the best I found so far: Johns Manville 1-1/2-in x 4-ft x 8-ft Polyisocyanurate Insulated Sheathing. It has a R-value of 9.8. $118 to do both of my garage doors.

I have two garage doors that self store ie roll up within themselves over door opening. Is there a spray-on insulation (I am thinking of bed-liner or undercoating spray) that will add some R value to the door? Any barrier would be better than none.

prodex insulation
prodex insulation

How is your garage door insulation with Prodex installation method better without creation the air space?


Hi David,
If I were you I'd pick up a small roll of the Prodex like material at your local home center and apply it to your door and see if it stays on.
If not a spray on radiant barrier will do the job. Check these guys out.
Let me know how things work out.

DIY Answer Guy
DIY Answer Guy

Thanks for pointing that out about using 1-1/2 inch strips to create an air space. That is the recommended installation technique for Prodex and does increase R-value.
The reason I opted to not use the recommended strips to create an air space was that we were using scraps from an attic project and didn't have the extra material. But you will still realize a significant improvement and energy saving installing the Prodex without the airspace.
Thanks for taking an interest and your question. By the way, are you insulating your garage door?