Steel Garage Door Construction, Insulation, Hinges, Rollers and Springs - 8 min

VIDEO SCRIPT:

STEEL GARAGE DOOR - Steel is the most prevalent used in garage door manufacturing. Steel does not breath like wood although it can rust if not protected. The paint and galvanizing systems of today have been developed to provide protection against rust. An advantage of steel is that its weight is constant and shape is consistent. Steel doors are generally lighter in weight making them easier to handle and operate. Most recently, plastic has entered the stage because of the unique properties it can offer. PVC, one of the most available and lowest cost plastics has good properties for door construction: dent resistant, impervious to water and is the same colour throughout so that scratches will not alter its colour.

PVC is a thermal plastic that softens with elevated temperatures so dark colours in direct sunlight should be avoided. You should also know that doors constructed of plastic require reinforcement to prevent sagging, fortunately these reinforcements can usually be hidden within the door so that the appearance of the door is maintained.

GARAGE DOOR APPEARANCE - The appearance of doors continues to be heavily market driven. Even though many garage doors are made from materials other than wood, many garage door owners want doors that look like wood. Steel construction offers limited variations to imitate wood appearance largely because the cost of imitating wood material requires dedicated, expensive equipment for each shape. Plastic door products excel in this area, tooling to shape and texture plastic is less expensive and therefore more variation is possible. Wood doors are available in many varieties of appearances. The panel door construction offers a range from the plain flat panel to raise panels. The raised panels can be basic or rounded for custom appearance, they can be nearly square or long and rectangular in shape.

GARAGE DOOR INSULATION - For a garage door, the ability to insulate is the ability for material to retard the flow of energy in the form of heat. Energy will always flow from a high energy source to a low energy source such as heat flowing to coal. Heat that flows through a material is measured in BTU's. BTU's is short for British Thermal Units. One BTU is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. R-Value is a measure of a materials resistance to heat flow and is the most commonly used measure for determining the performance of an insulation product. R-values are presented in numerical form with a high number indicative of good performance and a low number indicative of poor performance.

Expanded polystyrene, commonly referred to as EPS is one common form of insulation used in doors today, unlike some foam insulation products, EPS will not lose it's R-value over time. Polyurethane is the most common form of insulation used in energy efficient doors today. This type of insulation is much heavier than polystyrene and requires stronger springs.

SECTIONAL GARAGE DOORS - Now that you've seen some of the more common materials used in the manufacturing of garage doors, let’s take a look at the different sections you'll be assembling in the installation process. To most people there doesn't appear to be any difference in the sections used from the top to bottom but this isn't the case. At each lower corner of the bottom section is a bottom-bracket this plate holds the weight of the entire door. The bottom brackets purpose it so cradle the weight of the door, it also is the attachment point of the cables of the door, the bottom brackets rollers are also held in place via the bottom brackets. The next section up from the bottom section is called an intermediate section.

There will be a number of intermediate sections attached to the first intermediate, the number of intermediate section is directly related to the garage door's height. End-hinges or roller carriers are usually numbered from 1 on up, the reasoning is quite simple, most sectional doors employ a slope along the vertical track approximately 1/8" per foot. Roller carriers are designed to keep the roller shaft at an increasing distance from the door opening as the door travels vertically.

The slope of the track ensures that the door will pull away from the tight fit along the jams, hence roller carriers graduate in measure from the jam as intermediate sections are added. After the proper number of intermediates a top section is installed. The top section can be identical to the intermediates except for the hardware attached to it. This section is fixed with an adjustable top bracket or "fixture" that carries a roller, this rollers location must be adjusted to bring this section tight to the jam.

COUNTER BALANCE GARAGE DOOR SYSTEMS - The torsion spring power unit is comprised of shaft, tubular or solid depending on the load requirement and springs. This shaft is usually 6" to 8" longer than the width of the garage door. Before torsion springs are installed on the shaft they must be equipped with spring fittings. One spring end is wound onto a stationary sleeve or dead-cone, this end of the spring will not turn or wind. The other end is wound into a winding sleeve or winding-cone. This aluminum casting is identified by its 4 holes. Winding bars are inserted into these holes and the spring is then wound to its pre-determined tension. The winding sleeve is fastened to the shaft by set-screws. Cable drums must be incorporated which will transfer the shafts torque to the door.

This transfer is accomplished by the cable, these drums must also be fastened to the shaft using set-screws. In order to properly create torque in a torque spring it must be wound in the direction it was coiled. A left hand coil-spring must be wound to the left to develop torque, a right hand coil-spring must be wound to the right. On garage doors the orientation is to wind springs upward, therefore a left hand wound spring must be installed on the right hand side of the door, inside looking outside as a universal reference. A right hand spring must be installed on the left side of the door. As wire size wire size increases in diameter, it’s capable of increased torque. A door needs a given amount of inch pounds at the cable drum lever or moment arm to be balanced. Lever arms or moment arms of cable drums determine the amount of torque required to balance a garage door.

The necessary total torque will determine how many times the spring must be turned, normally a torsion spring is wound a quarter of a complete turn at a time. This is accomplished by inserting a winding bar. The installer utilizes two bars one bar is inserted into the winding sleeve casting hole and spring is turned one quarter of a revolution, at this time another hole in the casting is accessible and the second bar is inserted and a quarter turn is made. This process is repeated until the number of rotations to achieve the correct balance is achieved. In the case of extension springs it is necessary to select extension springs that will stretch to a proper length while delivering proper counter-balance or pull. This type of spring is directly attached to the door via cables that travel through the sheaves. Cable drums or spring fittings as previously described are not used in these applications.

We've just given you a brief overview of the materials, sections and other major components of a residential garage door. You've seen a preview of some of the installation skills you will learn, as you proceed through the series you learn many additional details and receive instructions regarding installation procedures.