What's Wrong with This Garage Door Insulation?

by Don Ames

If you don't want to read the whole article, at least go to the bottom of the page and watch the screen cast. Take a look at some real effective garage door insulation. No, I didn't make this up.

door structure

By the very nature of American household storage needs and the dilemma of how much expense to put into a garage when the house cost too much already, the car garage has turned into a storage garage. So, does a garage used for storage need garage door insulation? If it's not a storage garage, to hold all things we need but don't use, perhaps it has turned into a family room or bedroom by way of extended families that join together because they want too or because they have to. When the kids all gather around in the garage to play video games, does the garage need garage door insulation?

Put on your thinking cap, how many people do you know that have a garage full of everything except a car? Drive down a residential street in the evening and count the number of cars parked in the driveway. This usually means that there is no room in the garage for the car. Yikes, this is sounding biblical.

Concerning garage door insulation, when should you go to the extra expense of installing an insulated garage door. Should you use a different garage door for a car and another for a video game?

As you might guess, garage doors come in all different degrees of insulation and R-value. Different materials and different thickness of materials. In most cases, if the door is metal it is 26 gauge metal. A more expensive metal door will have more than one layer of metal. Be careful when you purchase a metal door, the metal thickness ranges from 24 to 27 gauge. The 24 gauge can be too light and not hold up over time. Especially when the little women backs into it with the car.

What is a garage door made of?

Insulation Sandwich

Most doors are made of either wood, metal or fiberglass. You don't want a wood door because they have no R-value and because they don't last as long as a metal or fiberglass door. Nothing like a old wood door that is missing a few screws and refuses to raise up without a forklift. The bottom section rots off because of moisture damage and the top section loses it composure and hangs down like a hammock when the door is open. The best R-value I have seen on a wood garage door is R-4.

As far as fiberglass doors go, I've never seen one so I'm not going to act like I have. They are probably pretty good, have good R-value and cost a bit more. Listed R-value for a fiberglass door is R-14.

I am familiar with metal doors and would like to put in a good word for them. A metal door is strong, paint-able, has good R-value, and lasts a long time. They come in a wide variety of designs and adding windows is no trouble. A less expensive metal door may have a R-value of R-6. Top of the line door with two layers of steel and solid-core, polyurethane insulation sandwiched between the layers, R-16.

My Recommendation.

My recommendation for all garage door applications is a single layer of 26 gauge metal with a layer of solid-core, polyurethane insulation attached to the inside. This door is strong, but not as heavy as two layers of steel, with an R-value around 8. I believe this is the best door for both the garage that holds a car and the garage that holds a couch and a big screen T.V. It is solid, has reasonable insulation and sound deadening qualities and doesn't cost an arm and a leg.

insulation retrofit

Don't get too carried away with your garage door insulation, after all, a garage door has many possible gaps both around the edge and between the panels. If your turning the garage into a family room, build a wall just inside the doors and insulate it like the rest of your home.

I would like to share a picture with you in the form of a screen cast of the inside of a garage I encountered the other day. I call it, what's wrong with this picture?

[jwplayer mediaid="14774"]

Thanks for stopping by Detect Energy, hope you will come back soon, but I won't leave the light on for you...

If the screencast will not open for you, go to this link, garage door.


Views: 88767

Tags: door, garage, insulation, metal, r-value


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Comment by Insulated Garage Door on November 5, 2013 at 4:53pm

I would use ThermaDoor garage door insulation, Therma Door insulation is a construction grade EPS laminated with a vinyl finish. But I would have to agree with a lot you have written above. 

Comment by Don Ames on January 15, 2012 at 12:39am

There were two things that struck me the minute I saw this garage. One was the potential for energy waste and the other was the potential for fire. This garage was the den/office/play room for a herd of teenagers. I had several energy saving retrofits I did to this home. One was to install a solar thermal array and, in conjunction with the solar hot water, take out the gas water heater that was in the garage and replace it with electric. I am glad the gas water heater is no longer in the garage.  Don Ames

Comment by Bob Blanchette on January 14, 2012 at 11:22pm

I've found simply adding the weatherstrip around the top and sides made a HUGE difference in the garage temperature. No more north wind blowing into the garage, didn't cost and arm/leg either :)

Comment by Bruce Navin on November 27, 2011 at 9:15am

Joseph, You are right, but the primary assumption of the article is that the garage is used as an extension of the living space and cars will not enter. While certainly not ideal, it seems to me that the insulated door would provide some benefit by improving the fenestration in terms of quality as a radiant barrier. I have had customers who called me after installations of insulated doors who commented that the heaters in adjacent rooms cycled less often after the installation of an insulated door.

Comment by Joseph Novella on November 25, 2011 at 10:00am

Garage doors don't need to be insulated!

Garages are outside a home's conditioned space and may contain dangerous contaminates such as car exhaust, CO, and chemical off gases. A home's living area should be air sealed and insulated from the garage. Unless the garage is heated an insulated door won't actually be doing anything. Garages should never be heated off of a central air system that might bring contaminated air back into occupant spaces. If a garage IS heated it should still have a well defined thermal/pressure enclosure separate from the main house.

Comment by Bruce Navin on November 22, 2011 at 3:34pm

Thank you, Don. Yeah, I've gotten my mix talked up before, too. Even when writing. And proofreading!

Comment by Don Ames on November 22, 2011 at 3:05pm


Thanks for the comment on my article, you demonstrate superior knowledge about garage doors and I appreciate getting that knowledge to the readers. Between the two of us, we did a pretty good job. The one thing I am embarrassed about is the fact that 26 gauge steel is thicker than 29 gauge. I was actually aware of that, but lost that piece of knowledge for my article. Thanks again,  Don Ames  www.detectenergy.com

Comment by Bruce Navin on November 22, 2011 at 1:03pm

I'm new to the Building Science industry, but I have over 15 years experience in the "Garage Door" industry. I worked in customer service, sales, and management and advised many homeowners, builders & architects. With all due respect to the author, there are some errors & incorrect statements in this article. Here is my take: 

1.) The lower the gauge number, the thicker the steel. So 24 gauge is thicker than 27 gauge. Sometimes, you may see (typically in commercial door applications) the term "Nominal 24 gauge". Different manufacturers have different tolerances with this term. The manufacturer I dealt with would only allow their tolerance to vary up to (thinner spots) 26 gauge whereas some I measured went as thin as 29 gauge. Most residential garage doors do not go as thick as 24 gauge-it is simply overkill to do so however if you have a non-insulated door, it is certainly a good move in terms of durability.

2.) I do not recommend using insulation kits on doors. The increased R-value is questionable because you have to rely on the quality of workmanship during the installation-gaps in the insulation will quickly diminish achieved R-values. Besides, there is no thermal barrier on non-insulated doors. Additionally, the fastening system of the panels may not be optimal when considering the effects of movement on a door when it is cycled. In addition to this, garage doors have either torsion or extension spring counterbalances that actually carry the weight of the door-and those springs are designed based on the weight of the door as it was manufactured. When you add weight to the door via an insulation kit, you will notice the door is heavier to lift. (the same thing happens with old wood doors because absorbed moisture & multiple coats of paint cannot be factored into the spring counterbalance system). Remember, an operator (or opener) does NOT lift the weight of the door-the springs do the lifting, and adding weight to the door with an insulation kit will cause additional stress on the operator and I have sold many replacement operators as a result. **Note: Springs carry a LOT of tension-don't play around with them or with the fixtures & fasteners that they are attached to.

3.) If memory serves me well, the higher R-values for an insulated steel door with a thermal break are 24 or so. Maybe higher.

4.) I would not recommend window kits for the same reason as avoiding insulation kits; not to mention the fact that they are expensive.

5.) Fiberglass doors are ok if you go with high quality, but rust prevention coatings have surpassed the benefits that f/g initially had over steel-and steel is less expensive and more UV & temperature stable. The only exception being that if you want radiant light in the garage via your opaque f/g door. 

6.) As mentioned above, weight is not a factor in buying a door as long as you buy it new from a reputable source and it is properly installed and adjusted. 

7.) Steel doors may be painted-but get advice from the door manufacturer before doing so-typically, you have to use a deglosser first, and then a high quality paint. This is best done by removing the door. (see note about springs) Most steel doors made nowadays will never need to be painted and many have lifetime warranty against rust (as long as you don't spray them with rock salt in the winter). If you do paint a door-you may have a problem with dark colors on insulated doors-including voiding warranties.

My recommendation is a steel insulated door with a thermal break and steel interior. Polyurethane insulation is better than polystyrene because of the higher R-value. The two better manufacturers for these are Clopay and Overhead Door Corp. 1-3/8" thick door will do just fine, but 2" will give higher R-values. They also have a very attractive interior look compared to other doors. Unless you really need light in the garage, I would stay away from lites (windows).


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