Many counties and districts have used the International Residential Code or the Consumer Product Safety Commission's "Guidelines for Swimming Pool Barriers" as a basis for pool barrier requirements. These two guidelines specify that a safety barrier must be installed around any constructed body of water that is more than 24 inches deep.
Any barrier must be at least 48 inches tall measured from the ground next to the pool, on the side of the fence outside the pool area. Openings in the fence or barrier, such as the space between pickets, must be a certain size, depending on its construction.
The CPSC recommends that a fence with horizontal members less than 45 inches apart have its horizontal members located on the pool side of the fence, with pickets spaced no more than 1 3/4 inches apart. This is to prevent a child from gaining a toehold in the fence and climbing over it.
If a fence has horizontal members more than 45 apart, the horizontal boards can go on the outside of the fence, and the pickets can be spaced up to 4 inches apart. This measurement is based in a young child's head and chest measurements; the aim is to keep a child from going through the fence, according to the CPSC.
There are separate measurements recommended for the openings in lattice and chain-link fences.
Gates for access to the pool must swing outward from the pool area, and have a self-closing and safety locking mechanism.
An above-ground pool taller than 48 inches is considered an appropriate barrier when its access ladder is detachable. If the pool is less than 4 feet tall, an appropriate barrier may be installed on the pool walls to extend the pool to the required height. Fencing can also be installed around the ladder or steps to make them inaccessible when children are unsupervised.
Each city or county in Maryland may adopt its own laws regarding swimming pool fences, so it's important to contact your local jurisdiction to determine what regulations you must meet. For instance, Prince George's County requires pool fences to be at least 6 feet tall. In Montgomery County, a pool must have a barrier if it's 18 inches deep or deeper, and fences must be at least 5 feet tall.