With doors that open vertically, debris and moisture picked up from the floor by the bottom edge can fall on people and goods as they pass through the door. This can be a hazard for sensitive goods, and it can be an annoyance to people using the door. Horizontally opening doors avoid this problem completely. If you use a vertically opening door, you can reduce edge drippage by installing a threshold or by raising the floor under the edge. Make the threshold gradual enough to avoid jogging vehicles excessively as they pass through the door. This is most important with vehicles carrying tall loads