The typical residential garage door is made up of four panels. Each one begins as a sheet of either aluminum or steel, 2 metals that can tolerate harsh climates.
The side that we’ll show has a baked-on coat of polyester paint. Depending on the model, the sheet passes through rollers that imprint a texture such as a simulated wood grain. Then it goes through a press that imprints a design. This model will have raised rectangles, others have horizontal stripes or no design at all. After an automated machine cuts the continuous sheet to garage door widths, another machine folds over the edges.
This creates 1 1/2-centimeter joints for attaching the panels. The polyester pain is elastic, so it simply stretches with the bending. Now, on the backside of the sheets, they hot glue metal plates to reinforce the various components they’ll later screw into the garage door, parts such as the lift handles, the hinges and the bracket for the electric opener mechanism. They also drill a hole through which they’ll later inject insulation. Now they slide two sheets together to form a panel.
They close off the ends with blocks of pine. This will prevent cold air from penetrating inside. They apply various stickers with installation, maintenance and safety information. Orange stick on dots mark the location of the metal plates into which the installer will screw the hinges and lift handles. Now, they attach an aluminum bar to the long ends of each panel, this holds the panel steady during the injection process.
After injection, the bars come off. They load the panels onto a carousel and begin the process of filling the hollow interior cavity with insulation. Through the hole they drilled earlier, they inject polyurethane foam, an expanding plastic insulation material that’s specially designed to penetrate hard to access spaces. As we see in this demonstration, the polyurethane expands and becomes rigid, this creates a solid core inside the garage door. Polyurethane is one of the lightest types of insulation, so it doesn’t make the garage door heavy.
Here’s what the inside of a panel looks like once the foam hardens. Now, workers install various components such as the rubber weather seal on the bottom panel. This seal prevents cold air and water from entering the garage under the door. Some garage door models have windows to allow in natural light. Workers first use a high-speed router to remove the rectangles where these windows will be installed, then they insert one of several windows styles available.
These are double sealed windows: 2 thermal panes with an aluminum spacer in between. The framing around the glass is available in different colors; it’s made of PVC, a synthetic resin that doesn’t discolor. The frame prevents water and cold air from penetrating. Workers pack the installation hardware, then they weigh the box to ensure no part was left out. At installation time, they attach the door panels at the joints with hinges.
A system of springs ensures the garage door is perfectly balanced and moves smoothly. If properly installed, you should be able to lift or lower the garage door using just 2 fingers.