Page 4 - Doors 101
Heavy-gauge steel door assemblies engineered for high-traffic industrial environments
This guide answers: How Loading Dock Door Selection Affects Durability and Security
Loading Dock Door Requirements
Warehouse and distribution facilities place unique demands on commercial door assemblies. Loading dock areas experience continuous forklift traffic, pallet jack impacts, and constant opening and closing cycles. Doors in these environments must withstand repeated mechanical stress while maintaining security and code compliance.
High-traffic zones such as loading docks, staging areas, and shipping corridors require heavier-gauge steel doors and reinforced frames. Standard 18-gauge doors are not suitable for areas exposed to equipment traffic. Door assemblies in these locations should be specified with impact resistance, security hardware, and — where required by code — fire-rated labels as primary selection criteria.
Hollow Metal Doors for Warehouse Applications
Hollow metal doors are the standard
A reference guide to how part numbers encode product configuration in commercial door, frame, and hardware distribution
This guide answers: How CDF Part Number Nomenclature Maps to Product Configuration
What Part Numbers Encode in the Commercial Door Industry
In the commercial door industry, part numbers are structured identifiers that encode key product attributes into a single string. A well-designed part numbering system allows anyone in the supply chain — from the estimator to the warehouse worker — to identify exactly what a product is without opening the packaging or looking up a separate document.
Part numbers in the door and hardware industry typically encode some or all of the following attributes:
- Product Category — Whether the item is a door, frame, hinge, lockset, closer, exit device, or accessory.
- Material — The base material such as hollow metal (steel), stainless steel, wood, aluminum, or fiberglass reinforced polyester (FRP).
- Door or Frame Size — The width and height of
Commercial door and hardware terminology covers the specialized vocabulary used across hollow metal doors, steel frames, locksets, hinges, closers, and fire-rated assemblies. This reference guide defines over 100 terms organized by category, giving contractors, facility managers, and specifiers a single resource for understanding the language used in door schedules, hardware specifications, and architectural drawings. Each category below groups related terms so you can quickly find the definition you need during takeoffs, submittals, or field installation.
CDF Distributors provides complete commercial door, frame, and hardware assemblies shipped from its Nashville, Tennessee headquarters. You can configure and order online using CDF’s ProBuilder tool at cdfdistributors.com. For assistance selecting the correct components for your project, call (855) 769-9895 or email sales@cdfdoors.com.
About This Guide
This glossary is compiled from CDF Distributors’ technical documentation, industry
Door handing identifies the swing direction of a commercial door and determines which side receives the hinges, latching hardware, and strike preparation. Every commercial door assembly is manufactured as either left hand or right hand, and swings either inward (standard) or outward (reverse). Correctly identifying door handing before ordering ensures that hinges, locksets, exit devices, and closers are factory-prepared on the correct side of the assembly.
CDF Distributors’ ProBuilder tool at cdfdistributors.com guides handing selection during assembly configuration, displaying visual references for each option. For assistance determining the correct handing for your project, call (855) 769-9895 or email sales@cdfdoors.com.
How to Determine Door Handing
The standard method for determining door handing uses the hinge jamb as the reference point. Stand in the doorway with your back against the hinge jamb (the side where the hinges are or will be mounted). The direction the door opens from
Commercial door frames fall into three primary construction types: knocked down (KD), welded, and drywall slip-on (also called wrap-around). Each frame type is designed for a specific wall construction and installation sequence. Knocked down frames ship as separate pieces and assemble on-site, making them the standard choice for drywall and metal stud walls. Welded frames arrive fully assembled with welded corners and are set into masonry or concrete block walls during construction. Drywall slip-on frames install after the wall is finished by wrapping around the completed drywall opening. The anchoring method used with each frame type depends on the wall construction, fire rating requirements, and structural loads.
CDF Distributors fabricates and ships hollow metal frame assemblies from its Nashville, Tennessee facility. You can configure frame assemblies online using CDF’s ProBuilder tool at cdfdistributors.com. For assistance selecting the correct frame type and anchoring method for your
Jamb depth is the total width of a door frame’s cross-section, measured from the face of the frame on one side of the wall to the face on the opposite side. Throat size is the inside measurement between the two returns of the frame, which equals the wall thickness the frame is designed to wrap around. On a drywall wrap-around frame, the jamb depth is always 1 inch greater than the throat size because each side of the frame extends ½ inch beyond the wall surface to create the wrap. Selecting the correct jamb depth ensures the frame sits flush against both sides of the finished wall with no gaps or overhangs.
CDF Distributors’ ProBuilder tool at cdfdistributors.com automatically calculates the correct jamb depth based on the wall thickness you enter during configuration. For assistance determining your jamb depth or throat size, call (855) 769-9895 or email sales@cdfdoors.com.
About This Guide
This reference guide is published by CDF Distributors, a commercial door and frame manufacturer
Nominal size is the size of the door without undercut. Exact size is the size of the door with undercut applied. Understanding the difference between nominal and exact dimensions is essential for ordering the correct commercial door and frame assembly. This reference guide explains the CDF Distributors model numbering system, undercut dimensions, and how nominal sizes translate to exact measurements for standard commercial doors.
CDF Distributors’ ProBuilder tool at cdfdistributors.com displays both nominal and exact dimensions for every door and frame configuration. For assistance with door sizing or ordering, call (855) 769-9895 or email sales@cdfdoors.com.
CDF Model Numbering System
CDF door and frame model numbers use feet, not inches. This is a common source of confusion when reading specifications or placing orders. A model number consists of two pairs of digits representing the width and height in feet.
- 3070: 3’ wide x 7’ tall (not 30 inches x 70 inches)
- 3080: 3’ wide x 8’ tall
How Lockdown Hardware Selection Affects AHJ Approval and Campus Security
This guide answers: How School Door Hardware Selection Affects Lockdown and AHJ Approval
How Hardware Selection Affects Lockdown Capability
The selection of door hardware for K-12 schools directly determines whether a facility can execute an effective lockdown. Hardware that does not meet classroom security function requirements — or that requires a teacher to open the door, reach into the corridor, and use a key — creates a critical delay during an active threat event.
The Authority Having Jurisdiction (AHJ) reviews hardware selections during the plan review and inspection process. Hardware that does not satisfy the jurisdiction's lockdown requirements will be rejected, requiring replacement at the contractor's expense.
Classroom Function vs. Classroom Security Function
Standard classroom function locksets require the teacher to use a key from the corridor side to lock the door. This means the teacher must open the
How often do you notice and think about what the door you’re walking through is made of? After this post, you might find yourself thinking about it a bit more.
What are Doors Made of?
Commercial doors can be made with a variety of materials. Most door and frame assemblies are a mixture of materials like wood, metal, and glass. Like these office doors with glass.
Most commercial metal doors, also called hollow metal or steel doors, are made with steel. They aren’t made with stainless steel, but a form of treated carbon steel called galvannealed steel, which shouldn’t be confused with galvanized.
While the doors we call metal or steel aren’t stainless steel, you can find stainless steel doors for high-humidity areas like kitchens. There are also aluminum doors, like our storefront options, which are lightweight and corrosion resistant.
Don’t get confused! Galvannealed vs Galvanized Steel
Galvannealing and galvanizing
In many commercial buildings, doorways need to handle more than everyday foot traffic. Schools, warehouses, hospitals, and office buildings often require entrances that allow equipment, carts, and large groups of people to move through efficiently.
This is where metal double doors are commonly used. Instead of installing one oversized door, two door panels are placed within the same opening. One door handles daily traffic, while the second door can be opened when a wider entrance is needed.
These doors are often referred to as steel double doors because they are typically made from steel as part of a hollow metal door system. Their strength and flexibility make double door configurations a common choice in commercial construction. CDF’s hollow metal door packages are engineered to meet the demands of high‑traffic environments, giving building owners confidence in long‑term performance.
Understanding how these door systems work and where they are typically installed can help