Parts of a deck frame — how load travels from the decking down to the footings
How a deck carries its load to the ground: decking → joists → the ledger (at the house) and the beam → posts → footings below the frost line. The joist can cantilever past the beam up to about ¼ of its span.
What this diagram shows
Side-section of a ledgered deck following the load path from the top down: deck boards on top, joists beneath them, a ledger bolting the inner end of the joists to the house, a beam carrying the outer end, posts under the beam, and concrete footings below the frost line carrying the load into the soil. The joist runs a short distance past the beam as a cantilever, limited to about one quarter of the joist span. A numbered key labels the six parts: decking, joist, ledger, beam, post, and footing.
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