If you’re going to unload heavy cargo from a truck, you would ideally do so at a dock that sits level with the truck’s bed or trailer. Dock doors are a type of loading dock that is slightly raised from the ground. So, what size is a dock door?
The standard dock door size is between 6 and 8 feet wide and 8 to 10 feet tall. Some companies might extend their dock doors to measure 8.5 feet wide and 34 to 14 feet high.
Why is there a wide variance in dock door size and does it matter? I’ll address these questions and many more in this guide.
What Is a Dock Door?
First, I’ll cover the basics for those who don’t know.
A dock door, also known as a dock-level door, is a type of loading dock. The bottom of the door is raised several feet above ground level to let truckers reverse directly in front of the door. This eliminates the need to lower ramps since the bottom of the trailer will typically sit flush with the bottom of the door.
Dock doors differ from grade-level doors, which are level to the ground. A grade-level door forces warehouses to use forklifts or hand trucks to lift cargo several feet high.
While the cost of manufacturing a warehouse with grade-level doors is considerably cheaper since the warehouse’s floor doesn’t need to be raised to the same level as a truck’s trailer. However, it can take workers much longer to load and unload cargo due to the height disparity between the warehouse’s floors and the floor of a truck’s trailer.
What Is the Standard Size of a Dock Door?
If you visit a hundred different warehouses, you might see a handful of different dock door sizes. This is because dock doors are not standardized, so companies are free to install dock doors of any size they wish. However, many dock doors will come in similar widths, heights, and raised heights from the ground.
A typical dock door would measure between 6 and 8 feet wide while standing 8 to 10 feet in height. The most variance between dock doors is in the distance between the bottom of the door to the ground.
The interior height of a trailer varies between trailer types. On average, it will be set at between 3 and 4 feet. So, even with a dock-level door, you might still need to raise and lower the ramps.
What Dock Door Size Do I Need?
There are 3 important measurements you should know before installing a dock door—the interior height of a trailer’s floor, the width of the trailer’s door, and the height of the trailer’s door.
Interior Floor Height
The interior floor height refers to the bottom of the trailer’s box. The thickness of the box’s floors combined with the thickness of the deck and the height of the tires should give you a rough estimate of how high to raise the dock door.
Ideally, the deck should be perfectly leveled with the raised height of the dock platform. That way, you won’t need to lower or raise ramps when loading and unloading cargo.
Trailer box heights vary, typically ranging from 114 to 162 inches. Discounting the interior floor height, the height of the door will stand between 5.5 and 12 feet tall. Since the doors of a trailer box swing outward, you will have to take into account the vertical clearance needed to allow the doors to swing open completely.
It’s safer to choose a dock door size that’s taller than you would actually need to reduce the risk of damage.
The trailer should be around 6 inches wider than the width of its doors. For instance, a step-deck trailer might measure 8.5 feet wide while the total width of the doors is just 7.6 feet. However, you should also accommodate the thickness of the doors since they will need to swing outward to allow warehouse workers access inside the trailer.
Why Does Dock Door Size Matter?
If you’re wondering why all of these figures matter, it’s simple—it’s all about efficiency.
Improperly sized dock doors can make it more difficult for workers to do their job, which will reduce performance, slow down loading and unloading times, and possibly cause truck drivers to be late for their next appointment.
While using ramps is common, even for dock-level doors, if there’s a massive height disparity between the trailer and the dock’s platform, loading and unloading cargo can become a safety hazard.
So, before placing an order for dock doors, make sure you have the 3 measurements figured out. That way, you won’t have to deal with the logistic headaches of dealing with improperly sized doors and reduced workplace efficiency.
Are Grade-Level Doors Better?
In terms of dock door designs, there is no better solution. The “more appropriate” dock door style depends on how your warehouse is designed. If you don’t have raised platforms, you can get by with grade-level doors. However, if you plan on moving goods from the ground floor to an elevated level in your warehouse, getting dock-level doors is the much more efficient dock style.
However, there is one huge difference you might want to consider. Dock-level doors require a ton of space to accommodate multiple trucks, whereas grade-level docks allow trucks and forklifts to drive right in. Of course, the tradeoff is that large trailers carrying larger hauls won’t fit inside grade-level doors.
How Much Space Does a Loading Dock Need?
If your loading dock uses dock-level doors, you should allow for at least 12 feet of space between each of the doors. That way, the trucks carrying goods won’t run the risk of bumping into each other as they reverse into the appropriate dock door.
The 12-foot figure comes from the horizontal space needed to swing the trailer’s doors open. If your warehouse deals with massive trailers with 7.6-foot-wide doors, you might want to add an additional 1 to 2 feet of space between each dock door.