What Is Standard Porch Rail Spacing?

Standard Spacing

• Standard porch rail spacing requires the space between each rail to be a maximum of four inches. While many building codes use the four-inch standard, codes may vary across states, counties and cities, making it a necessity for builders to check local building code to verify rail spacing standards. A building permit is required in most cities before construction begins on a remodel, addition or new construction and this requirement usually includes a porch and railing. City governments use the permit system and building inspectors to ensure structures are safe and meet local construction codes.

Verifying Local Code

• In the U.S., a city government's building department manages local building code and permit requirements. Building departments can be located by contacting the local government information number or by visiting the city government's website. When contacting the building and permit office, builders should verify whether a permit is needed to build a porch and ask about rail spacing requirements. The standard four-inch spacing should be followed where a permit is not required. Where a permit is required, building porches and other structures without a permit may trigger a visit from a city inspector, a fine and a demand from the city to stop construction.

Rails and Balusters

• Building codes are written with general safety in mind. According to “How to Build a House,” published by Habitat for Humanity, balusters or rails should be placed with a maximum space of four inches between each. Also, rails should be placed vertically with the bottom of the structure placed no more than four inches above the porch deck or floor. Four-inch spacing prevents anyone, especially a child, from inserting his head or body through the rail spacing and falling to the ground below.

Other Rail Standards

• Habitat for Humanity also points out that most building codes require a porch or porch type structure raised 30 inches or more off the ground to have railing. Rail requirements also include hand rails where there are three or more steps or risers leading to the porch floor. When steps are 44 inches or wider, code will also require hand railing on both sides of the steps. Hand rail height is calculated from the top surface of the step to the top of the hand bar -- balusters or rails are placed a few inches down from the top of the hand bar to allow a person's hand to move freely up the bar as he takes each step.