Typical porch deck construction is
joists running perpendicular to the
side of the house. The joists are then
supported by a ledger strip nailed to
the side of the house. Is this strong
enough? Let's see.
Suppose our deck is 6 feet deep by
12 feet wide, with joists placed 16
inches on-center. The inside ends of
the joists sit on the ledger or in joist
hangers attached to the ledger. A box
joist is nailed into the outboard ends,
and this box joist is supported by
posts. Building codes specify a working
design load of 60 pounds per square
foot on small exterior residential balconies.
Because the joists are placed
16 inches (1.33 feet) on-center, the
load