When exposed to moisture in the form of rain or humidity, steel tends to rust over time. This not only effects its appearance, but can also shorten the life of the door. Aluminum is naturally resistant to rust and corrosion, making it a better choice for coastal or humid regions. Steel is often painted, which requires regular maintenance and touch-ups. Aluminum is typically left with a shiny metal finish that requires no maintenance.
Aluminum is a relatively soft metal and is highly susceptible to dents. These dents may be caused by children playing in the driveway, accidental impacts or even wind and weather. Steel is much more durable and dent-resistant, even when exposed to fairly heavy bumps or impacts. If you have kids or live in a windy area, a steel garage door is often a better option than aluminum.
Steel doors are much heavier than aluminum models. The added weight makes them more difficult to operate manually and puts added tension and wear on spring assemblies. If you plan to skip the automatic operator, choose an aluminum door that you will be able to operate easily. Aluminum can also be an advantage if your operator breaks down, as you will still be able to open and close the door.
Aluminum doors tend to be much cheaper than steel on average, often by several hundred dollars. At the same time, aluminum doors are not as widely used, so it can be difficult to find replacement parts for these units. Even if you can find the parts you need, they may be more expensive than those for steel doors due to their relative scarcity.
Steel doors are available in a nearly infinite selection of colors, designs and finishes. They often feature pressed panel designs or windows and may even be embossed to look like wood. Aluminum is not as widely used, so buyers will find a more limited number of design options. While steel can be painted and refinished to change its look, aluminum is difficult to paint successfully and comes in only a handful of finishes.