When an exterior doorway of a building is used as a loading dock for vehicles, such as trucks and tractor/trailers, the perimeter of the doorway often includes a dock seal. Dock seals close off air gaps that would otherwise exist between the exterior face of the building and the back end of the trailer. Sealing the air gaps allows cargo from the rear of the trailer to be loaded or unloaded while dockworkers and the cargo are protected from the weather and other elements.
To seal the rear vertical edges of the vehicle, dock seals typically include two side seals running vertically along the lateral edges of the doorway. A top seal, header, or curtain extending horizontally across the doorway's upper edge is often used for sealing the vehicle's upper rear edge.
Although the actual construction of dock seals may vary, typically, side seals comprise a resiliently compressible foam core supported by a rigid backer, such as a wood plank. The foam core and backer are normally encased within a protective cover made of fabric or some other pliable material. Sealing is provided by backing the trailer up against the seal so that the seal compressively conforms to the rear shape of the trailer. The foam core provides the necessary compliance and resilience to repeatedly conform to the shape of various trailers; the outer cover protects the foam core from dirt, water and wear; and the backer provides solid structure for mounting the seal to the wall and for supporting the foam core so that the foam core does not twist and roll within the cover.
Although the compressible foam core usually seals quite well against the rear edges of the vehicle, the relatively rigid backer might not always seal so tightly against a wall having an irregular surface, such as a brick surface. Thus, air gaps might exist between the wall and the backside of the side seal. Such gaps might be sealed using caulk; however, a substantial amount of caulk might be needed for large gaps. An excessive amount of caulk can create a messy appearance, and the caulk can crack or tear when the side seal deflects under compressive pressure from a vehicle.