Insulated vs non-insulated garage doors

An insulated garage door has a foam or similar core between its outer and inner skins. A non-insulated door is a single layer of material. This guide explains the difference, what R-value tells you, and when insulation is worth considering.

A non-insulated steel door is a thin shell of metal, usually formed into panels. It is lighter and less costly, but metal on its own conducts heat. An insulated door is built as a sandwich, with a layer of insulation between an outer skin and an inner skin. Clopay describes it as a thick insulation core between two steel skins.

Not all insulated doors are the same. Manufacturers describe three common core materials.

• Polystyrene. A foam core. Clopay calls it cost-effective, with a good R-value for the money.
• Polyurethane. A foam that expands to fill the space. Clopay says it offers the highest R-value per inch of any insulation material, but it costs more. Garaga says polystyrene performs at about half of polyurethane at the same thickness.
• Fiberglass batts. Lower R-value, and Clopay notes they can settle over time, which reduces effectiveness.

Because these are manufacturer descriptions, treat them as general comparisons. Individual products vary.

R-value measures resistance to heat flow. The U.S. Department of Energy describes R-value as a measure of how well insulation resists conducted heat, and says the higher the R-value, the greater the insulating effectiveness. A higher number means less heat passes through.

Clopay says garage door R-values typically range from around R-6 to R-18, and that even lower R-values save energy compared with a non-insulated door. That figure comes from a manufacturer's marketing page and is not backed there by independent test data, so use it as a general idea, not a promise for any one door. Compare the numbers on the actual door you are considering, and ask what is included in the figure.

R-value is not the only thing that matters. Garaga says an R-value does not mean much if the door lacks effective thermal breaks, and that the door also needs to be airtight. Check the seals between sections, at the bottom and around the perimeter. Clopay adds that a door is only as efficient as its installation, since gaps or poor sealing can cancel the benefit. See weatherstripping and bottom seals.

Garaga gives guidance by use, with higher R-values for spaces that are heated or used as living space. Its page says an attached garage should have at least R-10, a heated and insulated garage at least R-12, and a workshop or home gym at least R-16, while a detached, unheated garage may need only a lightly insulated or non-insulated door. These are one manufacturer's recommendations, not a code requirement. The page does not cite a standard, so we do not present them as one.

• Attached garage. Insulation can reduce heat flow between the garage and the house. Clopay notes this is especially relevant for homes with attached garages.
• Workshop, gym or heated space. The more the space is conditioned, the more the door matters.
• Detached, unheated garage. A non-insulated door may be enough if the space is not used as living space.

In New Jersey, winters are cold and summers are warm and humid, which is why attached garages and rooms above garages are worth thinking about. We do not quote savings, because they depend on your house, your garage and the door.

• Strength. Clopay says insulated doors are typically built with thicker steel and the insulation adds structural integrity, helping resist warping.
• Noise. Clopay says the insulation acts as a sound buffer, reducing operational and outside noise.
• Cost. Insulated doors typically cost more up front than non-insulated models.
• Windows. Clopay says windows introduce thermal breaks in the door's insulation, lowering the overall R-value. See garage door windows and styles.
• Weight. An insulated door is generally heavier than a thin single-skin door, and the springs must be sized for the actual door.

The weight point matters when you swap one type for the other. A heavier door needs the correct springs. Springs are matched to the door by a technician, not chosen by color or by guesswork.

1. Look at the edge of a section, or the label on the inside, to see whether your door has a foam core. A single layer of metal is non-insulated.
2. Look for a manufacturer label or a sticker inside the door with the model and any R-value, and note it for a technician.
3. Look at the bottom seal and the weatherstripping for cracks, gaps or flattened rubber. You can see these with the door closed.
4. Look for daylight showing around the edges of a closed door.

Do not remove sections or hardware to look inside a door. Springs, cables and brackets hold dangerous tension. If you need to know the core type or R-value, a technician can identify it from the door's label or model.

Bring in a technician if you want to change from a non-insulated door to an insulated one, or if your door has damage that affects its sections. Replacing a door means resizing springs, cables and tracks for the new weight. Do not re-hang, swap or adjust sections and springs yourself.

• The door is damaged, crooked or off its track.
• The door is heavy to the opener, or a spring may be broken.
• You plan to add an insulation kit or panels to the existing door. Added weight changes the balance, and the springs may need to be re-sized.

Our technicians handle new garage door installation and weather seal replacement for doors that are leaking air. For comparison reading, see garage door materials compared and repair or replace the whole garage door.

• New Garage Door Installation
• Garage Door Weather Seal Replacement

• Garaga: What is R-value and what level do I need for my garage?
• Clopay: Improve energy efficiency with insulated garage doors
• U.S. Department of Energy: Insulation
• DASMA: Garage door safety