DASMA TDS 160 - Sectional Garage Door Terminology

When a technician says "the bottom bracket is cracked" and the homeowner thinks they mean the hinge, the conversation goes sideways fast. DASMA TDS 160 is the industry's official terminology standard, giving every part of a sectional garage door a specific, agreed-upon name.

What this data sheet says

TDS 160 is a glossary that defines the components of a residential sectional garage door system from the door itself to the operator and hardware. It is organized alphabetically and covers both structural parts and functional terms.

"This data sheet provides a standard set of terms and definitions for sectional garage doors and their components, intended for use by manufacturers, distributors, contractors, and end users."

A sample of terms defined in TDS 160:

• Back hang: the vertical distance from the top of the door opening to the ceiling, which determines how far back the horizontal track can run.
• Bottom bracket: the fitting attached to the bottom corner of the lowest door section, which holds the cable drum and the bottom roller.
• Flag bracket: the right-angle bracket that connects the vertical and horizontal track sections at the bend point.
• Section: a single horizontal panel of the door, typically 21 inches tall.
• Torsion tube: the steel shaft above the opening on which the torsion springs and cable drums are mounted.
• Winding cone: the fitting at the end of a torsion spring that is used to wind or unwind the spring during installation and adjustment.
• Stile: the vertical member at the left or right edge of a door section.
• Rail: the horizontal member at the top or bottom edge of a door section.

When it applies

TDS 160 is useful in any context where precise communication about door components matters:

• Describing a service problem to a technician. Using the correct term helps the technician know what to look for before arriving on the job.
• Reading manufacturer installation instructions. Instructions reference specific part names; TDS 160 resolves ambiguity when a term is unfamiliar.
• Writing commercial specifications. A door schedule or specification that uses DASMA-standard terminology is unambiguous across manufacturers and contractors.
• Home inspectors and insurance adjusters documenting door condition after a wind or hail event.

The DASMA terminology is widely adopted across North America, so a term from TDS 160 carries the same meaning whether you are talking to a manufacturer in Ohio or a technician in Denver.

For example: a homeowner calling to report that "the hinge at the bottom corner broke and the cable fell off" is describing a failed bottom bracket. A technician who hears "bottom bracket" immediately knows to bring a replacement bracket, a new cable, and a cable drum in case the drum shifted as well. The right term speeds the diagnosis and the parts order.

What this means for you

Learn the three most commonly confused terms: "bottom bracket" (the cable anchor at the corner of the bottom panel), "bottom seal" (the rubber or brush strip along the bottom edge), and "bottom panel" (the section itself). These three are regularly mixed up in service calls.

When calling for service, describe by location and function. Even without the exact term, saying "the metal bracket at the bottom right corner where the cable attaches" is useful. TDS 160 confirms that this is the "right-hand bottom bracket."

Inspectors and buyers: when a home inspection report mentions door hardware by component name, TDS 160 is the reference that defines what is being described and whether it is a deficiency.

G Brothers technicians use DASMA standard terminology. If you are ever uncertain what a part is called, ask us and we will identify it.

Full text and source

Download DASMA TDS 160 from the official TDS index at https://www.dasma.com/technical-data-sheets/.

This entry covers terminology for standard residential and commercial sectional garage door systems. Rolling steel doors, fire doors, and high-speed doors have additional component terms not included in TDS 160.