Guardrail System Design Requirements

A guardrail is an essential, yet often-overlooked safety feature. It is a barrier that keeps us from losing balance and falling from the edges of decks, balconies, staircases, and other open spaces. It stops our children from crawling through or climbing over and serves as a visual boundary to the danger beyond.

To function well, this life-saving device needs several key components. The entire assembly, or the balustrade, is made up of horizontal and vertical members. Top and bottom rails run horizontally along the edge of the unenclosed space, supported by vertical newel posts. Balusters – thin, vertical members – are placed between the posts. The assembly must be secured to the structure to resist horizontal and vertical loads.

Residential Guardrails

In residential applications, guardrails must be installed along the edges of decks, balconies, walkways, and stair landings that are higher than 30 inches from the surface below. The system must be placed within 36 inches of the open edge.

To provide adequate balancing support, the top rail cannot be lower than 42 inches above the walking surface.

A balustrade’s vertical members must be designed with several things in mind:

  • support of the guardrail system against lateral and vertical loads
  • keeping children from crawling or climbing over the edge
  • preventing children from getting stuck in the balustrade

Earlier building codes did not consider all these factors. As a result, gaps in railing proved to be a deadly hazard, with cases of children falling to their deaths after slipping through gaps of 6 inches or less. These preventable tragedies forced revisions of allowable railing gap dimensions. Current versions of the California Building Code (CBC) and the California Residential Code (CRC) require the space between two balusters, or a baluster and a newel post to prevent a 4-inch sphere from passing through.

To support the weight of a person leaning on a balustrade or accidentally walking into one, the assembly must be designed to resist a concentrated live load of  200 pounds  or a distributed live load of 50 lbs/ft applied at the top of the railing in the vertical or horizontal direction. Infill components, such as balusters, have a lower resistance requirement of 50 pounds per square foot; however, if the infill includes glass, a safety factor of 4 should be applied to the design load calculation. This means that glass panels in a balustrade must resist loads of up to 200 pounds per square foot.

While the individual parts of a guardrail assembly may comply with load requirements, the assembly itself should not detach from the building when the specified loads are applied. To ensure sturdiness, the system’s posts must be securely fastened to the structure.

Residential Stair Rail Requirements

Along open edges of stairs, stair rails must give their user continuous walking support while fulfilling the functions of a regular guardrail. In California, stairs rising more than 30 inches above the floor or grade must be equipped with a stair rail; stairs with over 4 risers must have a handrail.

To allow users easy handrail access, stair rails must be lower than regular balustrades, with the allowable height ranging from 34 to 38 inches.

Because the stair’s treads and the bottom rail form a triangle, achieving the maximum 4-inch railing gap may be difficult. The code addresses this challenge and allows a larger gap, which must be able to stop a 6-inch sphere from passing through.

In California, handrails can have a circular or custom-shaped profile. Circular profiles must have an outside diameter of 11/4 inches to 2 inches, while custom profiles require a cross-section of 21/4 inches or less. The perimeter dimension for custom profiles is restricted to a minimum of 4 and a maximum of 6 1/4 inches.

Handrail profiles that exceed the 6 1/4 inch limitation must have a finger recess area at least 5/16 inches deep on both sides of the profile to be graspable. The width of the handrail above the recess must fall within the 11/4 – to – 23/4 inches range. Please see the illustration below; for a complete list of requirements, click here.

Non-Residential Guardrail Requirements

The general public is exposed to fall hazards at every step. Multi-level shopping malls, hotel balconies, rooftop terraces, and every building with a staircase needs physical barriers to prevent falls. Some work areas, such as elevated loading platforms, are notably dangerous. For these reasons, guardrails in places of work and public are just as important as those at home.

Non-residential guardrails are regulated by the CBC, with additional location requirements found in Title 8 of the California Code of Regulations (CCR), the General Industry Safety Orders (GISO).

In buildings, GISO requires guardrails at all open sides of unenclosed work locations that are over 30 inches above the floor or grade. These include:

  • roof openings
  • open and glazed sides of landings
  • balconies
  • porches
  • platforms
  • runways
  • ramps
  • working levels

If the code-prescribed height of 42 inches cannot be achieved due to low overhead clearance, the GISO permits lower railings. To prevent items from slipping through the balusters, guardrails located over 6 feet above work areas and walkways must have a toeboard.

In work areas that are not buildings, guardrails are required where work areas are over 4 feet above another surface; these must also be equipped with toeboards if items are deemed likely to fall through the railing.

Where physical barriers obstruct functionality, GISO provides some common-sense exceptions to guardrail requirements. For example, theater stages and certain parts of loading platforms are exempt from mandatory guardrails. In other cases, the statute allows alternatives that achieve the same level of safety, such as gates and moveable guards. For a complete list of exceptions, click here.

Whether Your Project is Residential, Commercial, or Industrial – We Can Help

Flimsy guardrails are dangerous.. Whether you’re building a backyard patio or an acute care hospital, these critical safety features must be designed by professionals. Our engineers can make sure that your plans have all the necessary, compliant guardrail systems, and design strong, durable supports to handle the specified design loads. For a FREE quote and consultation, call us at (877) 892-0288.

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