We may earn revenue from the products available on this page and participate in affiliate programs. Learn More ›
Homeowners with a backyard may daydream about building the perfect deck for outdoor cooking, lounging, and entertaining. While there are many details to consider, one important safety detail is the height and spacing of the guards and railings. The guards are a continuous structural system that provides safety protection, and they are often (and mistakenly) called deck railings and commonly called guardrails. The railings are actually the graspable areas, like along a stair.
As with other residential building codes, the required deck guards and deck railing heights will depend on the municipality’s building codes. These codes set forth the requirements for any deck guards based on the platform height and the other dimensions of the deck to ensure the safety of anyone using it. While a low-platform deck may not need a guard to meet code requirements, a higher-platform deck or multilevel deck with stairs may call for continuous guards and a graspable deck railing with specific height and spacing requirements.
Since codes can vary by location, it’s always best practice to contact the local building department and inquire about any necessary permits, inspections, and specific building plan requirements before starting construction. However, there are a few standard guidelines about guards and railings that most municipalities follow, and they are good to keep in mind when planning a deck-building project.
Deck Guard Height Requirements
Building codes for a standard single-family residential dwelling are typically based on the International Residential Code (IRC), a set of minimum guidelines established to ensure the protection of public health, safety, and welfare. In many municipalities, deck builders follow the Prescriptive Residential Wood Deck Construction Guide (also referred to as the DCA-6 by deck builders) that’s based on the IRC. It dictates that deck guards must be installed on any deck higher than 30 inches above grade. The deck guard height should be a minimum of 36 inches, as measured from the surface of the deck to the top cap of the guard.
“Some places have increased the required height of guards to 42 inches,” says Glen Mathewson, Master Code Professional (MCP) and creator of BuildingCodeCollege.com. It’s “often related to how high the fall hazard is above that 30-inch trigger” above grade, he says.
Since local municipalities can have their own code requirements about guard height, check with your local building department to ensure it does not require a higher guard than 36 inches or specific installation methods. If a proposed deck will be lower than 30 inches above grade, it may not require guards to pass code (but a homeowner may opt to install them for safety or aesthetics anyway).
Deck Stair Railing Height and Guard Height Requirements
When purchasing materials for a deck, homeowners will need to consider both guards around the perimeter of the deck and the railing for the deck stairs. At least one graspable deck stair railing should stand at least 34 inches high, measured vertically from the nose of the stair tread to the top of the rail.
The IRC specifies that deck handrail height on a stair should be between 34 and 38 inches high, so homeowners may wish to use railing that is even higher than 34 inches for their deck stairs. However, it’s also an important safety detail that the handrail is smooth and continuous from the lowest riser to the highest riser.
Deck Guard Baluster Spacing
Balusters are the thinner vertical posts—often colloquially called pickets—that run between the bottom rail and top cap along the guards to prevent people and pets from falling off the edge of the deck or staircase. Code requirements dictate that balusters be spaced less than 4 inches apart. This safety guideline is based on the size of a small child’s head to prevent babies and young children from sticking their heads in the gaps between balusters.
The 4-inch rule also applies to the space between the bottom horizontal rail of the guard system and the deck surface.
Deck Cable Railing Spacing
Not all deck railings have vertical balusters. Another option that has been gaining in popularity is cable railing systems. These systems use either metal or wood posts with cable railing strung horizontally between them. As with the vertical balusters, the codes dictate the same spacing of less than 4 inches must be maintained between the cables. Many of these systems are created as kits, so the manufacturers often provide templates or pre-drilled holes in the posts that maintain this code-dictated spacing.
When cable railing started to appear on residential decks, discussions began about the “ladder effect” as it relates to the possibility of people climbing horizontal cables on decks. After a 3-year ICC Code Technology Committee review, it was determined there isn’t a need for further restrictions.
However, since cable railing is a newer guard system for residential applications, there is some debate about the flexibility of the cables. “I’d say one issue where things are very inconsistent, but not a legal adoption/amendment, is in cable guards and inspectors that believe they can pry them open to test opening restrictions,” says Mathewson. “The pulling open of cable guards is a researched subject and one that has been debated at code hearings, and it has not resulted in any guidance or authority in the IRC to do so.”
To eliminate this issue, cable rails are tightened during installation to not allow movement. Just like with all deck guards and other structural members, it’s best to check them periodically to make sure they are still performing as well as the day they were installed.
Deck Paneled Guard Railing Codes
As the building codes apply to all guards on a deck, the same codes apply to deck guards that contain glass or decorative panels. The open areas within the panel and between the panel and the surrounding guard posts, top cap, bottom cap, decking surface must be small enough so that a 4-inch sphere can’t pass through.
And just like the other types of deck guard systems, they have to be able to withstand 200-pound force and the balusters or other infill panels must be able to withstand at least 50 pounds of force per square foot.
Deck Railing and Guard Code Details
When it comes to stair design, there are a few exceptions to the IRC requirements for deck baluster gaps.
- In the triangular opening that’s formed where the stair riser, tread, and bottom stair rail edge meet, the opening should be small enough that a 6-inch sphere can’t fit through it.
- The graspable stair handrail must project at least 1½ inches from the wall or guard system.
- The space between the balusters on a stair guard system must not allow a 4⅜-inch sphere to pass through.
- A guard post is required every 6 feet along a stair.
Still, if the stairs risers are open, a 4-inch sphere must not be able to pass between the treads.
Other Deck Railing Codes
Depending on the style of deck a homeowner wants and the complexity of the build, certain sections of a deck may be subject to different building codes. For example, a split level deck may not need the same guardrail, stair rail, and baluster requirements on a section that’s lower than 30 inches as an upper section of the deck that is 30 inches or more above grade. A low deck may not need any railings.
“In residential occupancies NOT covered by the IRC, guards must be 42 inches tall under IBC for decks and balconies,” says Mathewson. “Balconies under IBC have some newer ventilation requirements prompted from the Berkeley tragedy” in 2015 when six people died and seven were injured after a balcony collapsed, he adds.
No matter what type of deck you want to build, always ensure the plans meet local building code requirements before you begin.
Final Thoughts
Decking guard systems and railings are an important safety feature of a backyard deck building project. Making sure the guard height and spacing meets the code requirements is essential for keeping your family and friends safe while they enjoy a backyard party on your deck.
Still, while the codes are in place for our safety, Mathewson warns that you can’t rely on deck guards to protect you from serious injury or death if you are not paying attention or being irresponsible while on a deck.
