The Latest IRC Building Code Changes from RailFX

With summer almost here, it’s a good time to share the latest information about building code changes. While many of you may still be using the 2018 International Residential Code (IRC), the 2021 IRC, published in October 2020, could be adopted in your area before you know it. There are changes to the 2021 IRC that impact the deck design of guardrails and handrails.

To keep you on the cutting edge — especially on the heels of Deck Safety Month — here’s an overview of changes that may affect your future deck designs.

New Rail Specs Depend on Function

Historically, guardrails and handrails had the same specification requirements within the building codes, even though they perform very different functions:

  • Typically installed alongside stairs and ramps, handrails must provide resistance in all directions, for people going up and down the stairway.
  • Generally located along the outer edges of the decks and elevated surfaces, guardrails (also referred to as guards in the IRC) are designed to keep people from falling off decks and, therefore, only need to provide critical support in one direction.

Previous versions of the IRC, 2018 included, stated both guardrails and handrails were subject to the same 200-lb concentrated load per square foot (psf) in any direction requirement. 

The new 2021 IRC clarifies the design intent of both types of rails, accounting for real-world usage of rails to determine loading requirements.

Previous versions of the IRC, 2018 included, stated both guardrails and handrails were subject to the same 200-lb concentrated load per square foot (psf) in any direction requirement. 

The new 2021 IRC clarifies the design intent of both types of rails, accounting for real-world usage of rails to determine loading requirements.

Table R301.5, Minimum Uniformly Distributed Live Loads in the second version in the 2021 IRC, dated November 2021, states both guardrails and handrails must support a concentrated load of 200 psf. This load requirement has been carried over from previous versions of the IRC.

The update for 2021 IRC is to clarify “Where the top of a guard system is not required to serve as a handrail, the single concentrated load shall be applied at any point along the top, in the vertical downward direction and in the horizontal direction away from the walking surface. Where the top of a guard is also serving as the handrail, a single concentrated load shall be applied in any direction at any point along the top. Concentrated loads shall not be applied concurrently.”

New 2021 IRC code changes help clarify the direction of loading for Guardrails. RailFX systems were already engineered to previous code revisions and are approved to handle loading in all directions.

New Requirements for Attachment of Exterior Guardrails

2021 IRC updates also include extra safety guidelines to ensure proper Guardrail attachments to wood-framed decks.

The 2021 IRC has a new section, R507.10, which details requirements regarding how the guardrails are attached to wood-framed decks. When guards are supported on the deck framing itself, IRC 2021 says “guard loads shall be transferred to the deck framing with a continuous load path to the deck joists.” And when guardrails are supported at the side of a deck joist or beam, the joist or beam must be connected to the adjacent joists to prevent rotation of the joist or beam. The code also goes on to say that “Connections relying only on fasteners in end grain withdrawal are not permitted.”

These new requirements do not dictate the exact connection methods but rather address the larger issue of how the guardrails are connected to the deck frame. You can continue to use standard blocking and fasteners. Our professional engineer (P.E.) approved RailFX system has guidelines for blocking and fasteners to ensure IRC code compliance and will continue to be updated as future IRC revisions materialize.

No Notched 4x4 Guard Posts at the Connection Point

New Section R507.10 also contains an important change regarding notched wood posts at deck guards.

Historically, building codes allowed notched 4×4 guard posts to be attached to the beam or the rim joist. It is now disallowed with the 2021 code update. 2021 IRC prohibits notching at the connection point when the post supports loads from the top and requires that the connection extends into the framing. Note that this change only impacts notching at the connection to the supporting structure.

We expect that this addition will help reduce accidents caused by guards that failed because of the notching. 

Safety First

At RailFX, we’re always building better ways to support you. Keeping you aware of building code changes is another way you can lean on us.

For more deck safety resources year-round, visit our Deck Safety page on our website, or each out to us via email.

Building a deck is a balance between form and function. Homeowners want a deck that increases their living space and blurs the lines between indoors and outdoors. However, without structural elements like walls, decks require railings to both define the space and, most importantly, keep users safe.

While a deck can be almost any shape, size and height, every deck railing needs to meet standardized building codes. Codes keep people and animals safe, particularly when it comes to elevated decks.

A cable railing system is a code-compliant railing that offers an aesthetic advantage with limited visual disruption compared to other railing options. All our cables are less than an inch in diameter and meet building codes following specific guidelines.

Code Considerations for Cable Railing. Which Code?

Municipalities, the state, and countries all issue building codes. When in doubt, choose the most conservative option. In many cases, the municipal code supersedes codes issued at higher levels.

For more information about handrail and guardrail codes, click here to view the International Residential Code.

A Note About Handrails and Guardrails

Building codes frequently have separate provisions and requirements for handrails versus guardrails. 

A guardrail must be present on every cable railing system. Guardrails, as defined by the International Residential Code (IRC), are a “building component or system of building components located near the open sides of elevated walking surfaces that minimize the possibility of a fall from the walking surface to the lower level.” Guardrails are required for all elevated decks and are the primary way of keeping users safe.

Handrails are defined by the IRC as “a horizontal or sloping rail intended for grasping by hand for guidance and support.” Handrails are required for at least one side of runs with four or more steps. 

In essence, guardrails prevent people from falling off a deck, while handrails help people move up and down stairs safely.

cable railing codes
railing graspability

What Is Graspability?

A handrail must be high enough to stop someone from falling over and sturdy enough to support someone’s weight. It also needs sufficient graspability. Graspability refers to the specific shape requirement for someone to hold onto the handrail. 

Many cable railing systems come with materials to build code-compliant handrails and guardrails. Some companies, such as RailFX, offer several rail designs that accommodate graspability requirements while providing a stylish look.

However, if you’re using your own materials, check the IRC and any local codes to ensure your guard and handrails are sufficiently graspable. 

Sphere Rules

Sphere rules are fairly straightforward and apply to all railing systems. IRC sphere rules state that the spacing between railing components cannot allow a 4” sphere to pass through it. Stairs are an exception. They have a 6” sphere rule between the step treads and the bottom rail.

Cable railing doesn’t have the same rigidity of wood or steel balusters. Therefore, you can’t simply measure the space between cables. Install cables close enough together so even if they stretch, a 4” sphere still can’t pass through. Contractors often install cables with 3-3½” spacing.

Tensioning is another requirement for cable railing. Applied tension to the cable helps resist a 4″ sphere from passing through. It is a critical specification to ensure the safety of a cable railing system.

Sphere railing rules

Other Safety Considerations


Tension is the critical component to meeting sphere rule requirements. It impacts the cable’s load-bearing capability if someone or something runs into it. Tension keeps the cable taut enough to comply with the sphere rules and is an important factor in the safety of the system.

Different materials have different stretch properties, and high tension cables can lose tension over time, which can negatively impact their code compliance. Stainless steel typically stretches less than aluminum, and the recommended cable configuration is a 1X19 cable—that is, 19 wires woven into one stronger cable structure—to maintain strength and flexibility.

Posts should be strong enough not bow under high tension. Choose the Invisiware Receiver® hardware by RailFX. It’s  easy to create the correct amount of tension by using a simple Allen wrench to adjust tension as needed.

The Inivisiware Receiver, our mounting hardware, is strong enough to withstand all forces.  A Professional Engineering Firm with stamps in 38 states officially reviewed The RailFX system and concluded our system meets all applicable code requirements.


Railing safety considerations


Often there is a loss of tension over time due to stress on the wires, relaxation and applied loads, such as kids trying to use it as a ladder. However, tension is easily adjusted with an Allen wrench using hardware such as our Invisiware receivers.

While horizontal cable infill is a perfectly acceptable and safe option, some still have apprehension using this system. In this case, vertical cable infill is a good alternative as it eliminates the ability for climbing on the infill. This option is inherently more expensive and slightly more visually disruptive due to the number of cables needed.

Which Cable Railing System Should You Choose?

RailFX offers a number of code-compliant railings, including RailFX cable railings. Engineered with stainless steel hardware, system railings are long-lasting without interrupting a homeowner’s view and many kits are easily re-tensioned using only an Allen wrench. For more information, visit our website.