Insulated vs non-insulated garage doors in a Nebraska winter
Short answer
If your garage is attached, heated, or has a finished room above it, buy an insulated door. R-13 is the sensible floor and R-18 is worth the money if you actually spend time in the space. If your garage is detached and unheated, an insulated door will not pay for itself in energy savings, and we will tell you that before we quote it.
What R-value actually measures on a garage door
R-value is thermal resistance. Higher is better. The problem is which part of the door the number describes.
A published garage door R-value is a calculated value for a single door section. It adds up the steel skin, the insulation core, the interior facing and the air films. It does not account for the joints between sections, the stiles, the end caps, the weather seals or the perimeter of the opening. Those are exactly the places heat leaves.
The standard that matters
ANSI/DASMA 105 tests a complete installed door in a controlled chamber and reports a U-factor, not an R-value, because U-factor covers the whole assembly including joints and seals. DASMA Technical Data Sheet 163 is explicit that the two come from different methods and are not interchangeable. Ask two questions of any supplier: was the number produced under ANSI/DASMA 105, and is there a U-factor for the complete door. A number with no standard behind it is marketing.
R-6, R-13 and R-18 in plain terms
R-6 builder grade. Usually a thin polystyrene sheet between two steel skins. It is what goes on spec homes because it costs the builder the least. In a Nebraska January it does very little.
R-13. Polyurethane foam injected between two steel skins and bonded to both. The foam expands and fills the cavity, which is why the panel is noticeably more rigid and quieter. This is the value point for most Omaha homes and what we recommend for any attached garage.
R-18. Same construction, thicker section or denser core. The difference is real if you heat the garage, work in it, or have a bedroom above it. If you park two cars and close the door, the difference is small.
The step from R-13 to R-18 on our doors is $260. That is the whole decision, and we will tell you honestly whether your garage is the kind that will notice it.
Will an insulated door lower your heating bill
Probably not by much, and we are not going to pretend otherwise.
An attached garage is almost always outside the home's thermal envelope. The insulated surfaces protecting your house are the wall between the garage and the living space and the ceiling under any room above. The garage door is a wall between the garage and the outdoors, and the garage is already unconditioned.
What an insulated door does is raise the garage's own temperature, which reduces the temperature difference across the shared wall. The effect is real but modest. Anyone claiming a new garage door cuts your heating bill by 20 percent is guessing.
The savings become genuine in three situations:
- The garage is heated, so you are paying to condition that space directly
- There is a finished room above the garage, and that floor assembly is often poorly insulated
- The shared wall to the house is uninsulated, which is common in older Omaha housing
When insulation is genuinely not worth it
A detached, unheated garage used for parking and storage. There is no conditioned space to protect. You get a quieter door and a stiffer panel, which are legitimate reasons to buy, but no energy return. If that is your situation and cost is the priority, a non-insulated door is a defensible purchase.
We would still steer you toward a bonded two-layer door for a reason unrelated to R-value. A foam core bonded to both skins is structurally stiffer. It resists dents, it tracks straighter, and it usually carries a better wind pressure rating. Sometimes the insulation is worth buying for the panel rather than the number.
What matters as much as R-value
Seals. A door with an R-18 section and a failed bottom seal performs worse than a properly sealed R-13 door. Check the bottom astragal, the perimeter stop weatherstrip on both jambs and the header, and the seals between sections.
On a windy Omaha night, air moving around a poorly fitted door carries more heat than conduction through the panel.