Pool barrier
Also called: pool fence, safety barrier, pool safety fence.
A pool barrier is the fence, wall or railing that keeps children out of a pool. Under the ICC's model pool code (ISPSC section 305) it stands at least 48 inches, measured on the side facing away from the pool, passes no 4-inch sphere, and has a gate that opens outward, self-closes and self-latches.
Why it matters
Under that code an above-ground pool's wall is its own barrier only when it is at least 48 inches high all the way round, the pool maker allows it, and the ladder or steps can be secured, locked or removed, unless the steps are surrounded by a barrier. A deck with a railing and a gate at the top of its stairs is that barrier, with no handholds or footholds outside. The gate takes a lock and, new in the 2024 code, may not swing over stairs. Codes are amended locally; your building department's version is the one that counts. A closed above-ground pool still needs its barrier.
In numbers
A gate latch reached from outside sits at least 54 inches up, and equipment outside the barrier, such as the pump or filter, sits at least 36 inches from it so it can't be climbed.