Balluster Spacing Calculator

The terms “baluster,” “spindle,” and “post” are often used interchangeably. However, posts differ from spindles or balusters in that a post will always make contact with the base of the deck itself. These posts divide railing into sections, where spindles or balusters are placed to provide a safety barrier. Depending on the length of these sections, it will also determine how far apart your spindles should be placed from the center point.

While a spindle or baluster can touch the deck, they often have a bottom railing to hold them in place. Composite balusters never touch the deck and are held in place four inches or less from the top of the deck’s surface. On the flipside, a post will touch the deck every time it’s used, providing a steady support system.

If you’re building a new deck, making sure your structure is compliant with local building codes is important when securing your building permit. One area of safety that should not be overlooked is proper baluster spacing on your deck’s railing.

How Far Apart Should Spindles Be On a Deck Railing?

U.S. building codes mandate that balusters have no more than a 4-inch gap between them. This relatively tight amount of spacing still allows for visibility between spindles, but also stands as a safety measure to prevent small children from becoming stuck between spindles or from slipping through the balusters.

To make sure your baluster spacing is up to code, follow the best practice to include three balusters for every foot of railing. This will ensure that they are placed no more than 4 inches apart, although spindles can be placed from the center point, but not to exceed a 4-inch gap, depending on the aesthetic you want to achieve.

Use the deck baluster spacing calculator to calculate how many total balusters you’ll need to be sure your deck railing adheres to code.

Baluster Width

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Space Width

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Sections (post to post)

Baluster With Steprun