A drop beam is the supporting member of framing that is installed beneath the deck joists, that is supported directly with the 4×4 or 6×6 posts.
When the deck is close enough to the ground, often the drop beam is set directly on the footings.
When the deck is attached to the home, the drop beam is installed under the deck joists opposite the house.
When a deck has an unusual shape, drop beams can be installed under the joists to allow the cantilevered joists to be trimmed.
Freestanding decks will usually have drop beams installed beneath both ends of the deck joists, so that attachment to the house is not necessary, because the deck is supported at both ends.
