The majority of loading dock areas are designed with a level grade approach, the truck backs in level and square to the building’s foundation and wall.
The second most common is a declining approach at the loading dock area. A declining approach increases the risk of damage to the building walls above the overhead doors as the top of the incoming truck can potentially contact the wall before the back of the truck bed contacts the dock bumpers. https://www.pentalift.com/wp-content/uploads/2020/11/Projected-Pit-Dock-leveler-Benefits-1-1.pdf
Declining approaches can be managed to protect the building walls and to select the proper dock seal for the most efficient energy seal. The first step is to determine the percentage of decline at the loading dock area.
To begin measure from the finished floor level down to grade at the face of the foundation wall. Dock heights vary however 48” high is very common and is used for this example calculation.
Second, using a straight line at floor level projecting out, 50’ out from the face of the foundation wall measure down to grade. For example, it could be 18” to grade therefore 48” – 18” = a 30” rise over a 50’ (600”) long run.
Divide the 30” rise by 600” = a 5% decline at the loading dock area. Project the pit 1” per percentage of decline. Based on the sample calculation the dock leveler installation should be projected a minimum of 5” beyond the face of the foundation wall, the projected pit with dock bumpers installed will prevent the truck from contacting the wall above the overhead door.
With this example, compression style dock seal side pads should project 5” more at the bottom than at the top. The dock seal side pads will now be tapered to match the decline and align evenly with the back of the truck providing a proper seal and minimizing any pressure on the building wall caused by over-compression of the dock seal.
Inclined approaches are rare and have no impact on the dock leveler or dock bumper installation. If the loading dock is to be equipped with compression style dock seals use the same calculations as above to determine the percentage of incline and taper the side pads accordingly. As opposed to a rise over run calculation it becomes drop overrun.
For assistance addressing a non-level loading dock approach or any loading dock topic please contact the Pentalift Sales Department.