Garage door

Modern sectional garage door

Traditional single-panel garage door

Garage door hardware

A garage door is a large door allowing access to a residential garage that opens either manually or via a motorized garage door opener. Garage doors are large enough to accommodate cars and potentially other vehicles. The operating mechanism is usually spring-loaded or counterbalanced to offset the door's weight and reduce the human or motor effort required to operate the door.

Garage doors are made of wood, metal, or fiberglass, and may be insulated to prevent heat loss. Less commonly, some garage doors slide or swing horizontally.

Design

An electric garage door opener operates on the center track

A typical version of an overhead garage door used in the past would have been built as a one-piece panel. The panel was mounted on each side to an unequal quadrilateral-style lifting mechanism. Newer overhead garage doors are now generally built as several panels that are hinged together and are guided by rollers along tracks on each side. The weight of the door may be 400 lb (180 kg) or more, but is balanced by either a torsion spring system or a pair of extension springs.

Garage doors can be made of many materials, but steel, aluminum, wood, copper, glass, PVC, and polyethylene are the most popular materials. Some manufacturers incorporate polyurethane foam insulation within the door panel(s).

A garage door opener is a motorized mechanism for opening garage doors. It can be activated with a remote control or a wall-mounted button or keypad for added convenience, safety, and security.

Materials

Wood garage doors offer aesthetic appeal, but are high-maintenance and may be expensive. Low-priced wood garage doors may warp and break easily.

Aluminum garage doors are usually found in commercial settings, being uncommon for residential applications. Aluminum is typically only used for full-view garage doors (doors that are made up of glass sections divided by aluminum stiles). Aluminum doors are rust-proof and low maintenance.

Fiberglass and vinyl garage doors are composite units, combining a steel core behind a fiberglass or vinyl skin. They also have polyurethane insulated base sections or other types of foam insulation. These types of doors perform similarly to steel doors and can be designed to effectively emulate wood (namely fiberglass units), but they may be more expensive than steel doors. Fiberglass doors are commonly used near an ocean, where salt water can ruin regular steel doors.

Steel doors have a variety of sizes and styles, provide strength and security, are cost-competitive, and may have optional insulation. Extra strength is available with two or three layers of galvanized steel with a low gauge number (a thickness of 0.6-0.7 mm).

Stamped steel construction

Sectional steel doors with exterior cladding, in the style of old carriage house doors

A common material for new garage doors is sheet steel, formed or stamped to resemble a raised-panel wooden door. Steel doors are available uninsulated, insulated, and with a three-layer "sandwich-style" construction. A design mimicking carriage house doors has become popular since the early 2000s, and many manufacturers clad the exterior of a steel door with composite, vinyl boards, or other trim to give it the appearance of wood.

Insulation

In situations involving residential attached garages, the insulating effectiveness of a garage door is essential to avoid overheating or freezing problems, as well as for comfort and energy savings.

History

The history of the garage door could date back to 450 BC when chariots were stored in gatehouses.

In the United States, they arose around the start of the 20th century. As early as 1902, American manufacturers, including Cornell Iron Works, published catalogs featuring a "float over door". Evidence of an upward-lifting garage door can be found in a catalog in 1906.

Types

Single-panel

Single-panel door with jamb-type hardware

Single-panel door on tracks

Single-panel doors are constructed from one monolithic panel. A single-panel door swings up and overhead with a hinge on each side from the closed position to the fully open position. A disadvantage of single-panel doors with jamb-type hardware is that the swing-up arc of the door occurs partially outside the garage, requiring a vehicle to stop and park an increased distance away from the door to avoid being hit when it is opened.

Single-panel doors may also be installed with a single horizontal track on each side of the garage, and a roller mounted at the top of the door on each side. Using tracks, a car can be parked much closer to the door, as the door is positioned entirely inside the garage when opening. A single-panel door running along tracks has less of an arc when raising and lowering the garage door than with jamb-type hardware.

Sectional

Sectional doors usually have three to eight panels and slide up and overhead in an approximate L shape. Sectional doors occupy the same internal garage space as single-panel doors, with two advantages:

• Sectional doors do not require any space outside the garage to open. A vehicle may park very close to the garage before opening the door.
• Each panel of a sectional door has a connection to the door tracks. This increases durability and robustness compared to monolithic doors, which have only a few track connections for the whole panel.

Side-sliding sectional doors also exist, trading ceiling space for wall space.

Roller

Roller door mechanism

Overhead roller door

Roller doors, sometimes called "sheet doors", are usually constructed of corrugated steel. They evolved from window and door coverings. Corrugations give the door strength against impacts, and other materials can be used where strong impact resistance is not required, such as transparent corrugated fiberglass.

Roller doors cannot be effectively insulated; they have a typical insulation R-value of 4.9 to 5.2. By comparison, a sheet steel garage door has a typical insulation R-value of 0.5 to 2.7. An application that needs more thermal insulation typically uses a foam-filled sectional garage door, which provides typical insulation R-values of 6.1 to 6.4. In the UK (and other parts of the EU), 'insulated' roller garage doors are available, using an aluminum lathe filled with polyurethane foam.

A typical single-car garage roller door has a preloaded spring inside the rolling mechanism, reducing the effort required to open the door. However, oversized roller doors in commercial premises are typically not sprung (except in the US); instead, a manual pulley and chain system, or a geared motor, is used to raise and lower the door.

Spring mechanisms

Torsion springs

A torsion spring counterbalance system consists of one or two tightly wound springs on a steel shaft, with cable drums at both ends. The apparatus mounts on the header wall above the garage door and has three supports: a center bearing plate with a steel or nylon bearing, and two end bearing plates at both ends. The springs consist of a steel wire with a stationary cone at one end and a winding cone at the other. The stationary cone is attached to the center bearing plate. The winding cone consists of holes every 90 degrees for winding the springs, and two set screws to secure the springs to the shaft. Steel counterbalance cables run from the roller brackets at the bottom corners of the door to notches in the cable drums. When the door is raised, the springs unwind and the stored tension lifts the door by turning the shaft, thus turning the cable drums and wrapping the cables around the grooves on the cable drums. When the door is lowered, the cables are unspooled and the springs are rewound.

Garage door manufacturers typically produce doors fitted with torsion springs that provide a minimum of 10,000 to 15,000 cycles (one cycle being a single opening and closing sequence) and are guaranteed to last for three to seven years. Most manufacturers offer 30,000-cycle springs. However, it is essential to remember that if the garage door's weight is increased by adding glass, additional insulation, or even several coats of paint, the torsion spring's life may be significantly reduced. Additionally, springs in highly humid environments such as coastal regions tend to have a significantly shorter lifespan due to corrosion.

Other factors like poor garage door maintenance or loose components shorten torsion spring life. Owners are advised to avoid applying grease to garage door tracks, as it makes the wheels slide in their tracks without turning. Only bearings, hinges, and spring wires require lubricant.

Extension springs

An extension spring counterbalance system consists of a pair of stretched springs running parallel to the horizontal tracks. The springs lift the door through a system of pulleys and counterbalance cables running from the bottom corner brackets through the pulleys. When the door is raised, the springs contract, thus lifting the door as the tension is released. Typically, these springs are made of 11 gauge (3 mm) galvanized steel, and the lengths of these springs are based on the height of the garage door. Their lifting weight capacity can be identified by the color painted on the ends of the springs.

Safety

Garage door electric eye

Garage doors can cause injury and property damage (including damage to the door itself) in several ways. The most common causes of injury from garage door systems include falling doors, pinch points, improperly adjusted opener force and electric eye safety settings, attempts at do-it-yourself repair without proper knowledge or tools, and uncontrolled release of spring tension on torsion spring systems.

A garage door with a broken spring or the wrong strength can fall with great force. Because the effective mass of the door increases as the garage door sections transfer from the horizontal to vertical door tracks, a falling garage door accelerates rapidly. A free-falling garage door can cause severe injury or death.

The sections and rollers on garage doors represent a significant pinch hazard. Children should never be allowed near a moving garage door for this reason. On manually operated garage doors, handles should be installed vertically to promote "vertical orientation of the hand".

Mechanical garage door openers can pull or push a garage door with enough force to injure or kill people and pets if they become trapped. Modern openers have “force settings” that make the door reverse if it encounters too much resistance while closing or opening. Any garage door opener sold in the United States after 1992 requires electric eyes—sensors that prevent the door from closing if obstructed. Force settings should cause a door to stop or reverse on encountering more than approximately 20 lb (10 kg) of resistance, and electric eyes should be installed a maximum of 6 inches (15 cm) above the ground. Many garage door injuries, and nearly all garage door-related property damage, can be avoided by following these precautions.

Certain parts, especially springs, cables, bottom brackets, and spring anchor plates, are kept under extreme tension. Injuries can occur if parts under tension are removed. Severe injury or death can be caused by the projectile pieces of a failed torsion spring; many people have been injured or killed trying to adjust torsion springs, and special training and procedures are required to modify a torsion spring safely.

Extension spring systems should always be restrained by a safety cable that runs through the middle of the spring, being tied to solid points at the rear and front of the horizontal door track. The safety cable minimizes hazards to bystanders if a spring, pulley, or cable breaks under tension.

Maintenance of garage doors is described in the manufacturer's instructions and consists of periodic checks for correct operation, visual inspection of parts, and lubrication.

External links

Media related to Garage doors at Wikimedia Commons