Introduction to residential garage doors

This article is a basic introduction to residential garage doors. Use this answer to discover the following information:

• Type of doors
• Door components
• Sectional door tracks
• Garage door openers

Types of doors

Residential doors can be one piece or sectional. Sectional doors are far more common. They can be referred to as overhead doors sometimes because they roll on track that is over your head. Sectional doors are made of panels. One piece doors used to be referred to as California doors and are made of a single panel that flips up to open.

The materials that the doors are made of vary. They can be fiberglass (very light), aluminum, metal, and wood (very heavy). They can be insulated to keep in heat. Some may have glass in one or more panels. When doors have insulation and/or glass, they tend to be heavier. Wood doors (called carriage house doors) tend to more decorative and very heavy. Wood doors usually need a more robust operator, like a 3/4 horsepower (HP) unit.

Illustration of a one piece door:

Components of the garage door

Since the sectional door is most common, we will focus on that style of door. Let's look at the components of a sectional garage door:

1. Panel with glass
2. Panel
3. Vertical track
4. Cable drums
5. Torsion bar w/spring -or-
6. Extension springs
7. Track hanger
8. Horizontal track

The panels are joined together with hinges and each hinge has a roller that fits in the track sections. As the door moves, the rollers roll in the track. The track sections are joined by a curved track that can be of different radius.

However, the track and rollers really just guide the door. The door itself is really heavy; they can weigh from a couple hundred pounds to a thousand pounds. Because of this, a door needs a counterbalance. This is done with either a torsion bar with springs or extensions springs. Older doors used a system of pulleys and sandbags. The torsion bar is far more popular than the extension spring.

If you look on each side of the door, there are two cables that attach at the bottom of the door and wind around drums at the top. The drums are attached to a long bar (torsion) that has a spring. As the door moves, this spring winds or unwinds to counter the weight of the door. Chamberlain does not manufacture or provide support for the door components. We do not assist in replacing, repairing or adjusting door springs. These springs are under a high amount of tension and service must be done by a qualified door systems technician.

Sectional door tracks

Sectional doors come in different styles for the tracks. They can be standard, high lift, vertical lift and low head room. This refers to the types of tracks that the door rolls. All residential and commercial door tracks are normally 2" inches in width. Heavier door and industrial garage doors are supported by 3" inch tracks.

Standard sectional door

The door goes up slightly before the track bends for the door to open.

High lift doors

For these doors, the door actually lifts straight up further before the track bends. These are used with applications that have a lot of headroom.

Full vertical lift doors

These doors have little to no bend in the track. The door goes straight up. These are typical of commercial applications like warehouses.

Follow the pitch

These doors have a track that bends and follows the pitch of the roof. These are found occasionally in residential applications.

Low Headroom

These are for applications where there is very little headroom. The space between the door track and ceiling is very limited. In these applications, the door starts going back down the track, it does not go up (there is no room) like standard sectional doors. There are two types: front and rear mount. In front mount, the torsion bar is still above the door. In rear mount, the torsion bar is mounted back at the end of the track.

Garage door openers

To open the door, you need an opener to open the door. That is where Chamberlain comes into the picture. There are two types of garage door openers, trolley or side mount (aka jackshaft).

Trolley openers are the more traditional of the two. It has a motor that hangs from the ceiling of the garage with a rail that extends to the wall above the garage door. On the rail, a trolley connects to the door. The motor pulls or pushes the trolley to open and close the door. Trolleys use chains, belts or long screw drives to move the trolley.

Side mount or jackshaft operators are mounted to the side of the garage door. They work by turning the torsion bar to raise or lower the door. As mentioned before, on sectional doors there is a pulley with a cable that goes to the bottom of the door. As the bar turns, this raises or lowers the door. When using a jackshaft, care has to be taken to prevent "cable throw." This happens when the door does not move (may be stuck) but the opener keeps turning the torsion bar and unwinds the cable off the drum.

*On high lift doors, an extra panel(s) are needed so the door extends up close to where the track bends. These are often called "dummy panels."

**Low headroom present many problems. There may not be enough room for a trolley unit. Using jackshaft has other installation issues. The drums are often backward wound so the bar spins in reverse for open or close. Mounting a jackshaft on a rear mount is difficult.