There’s probably nothing in the world more frustrating than going through all the trouble of installing a new railing onto your deck only to fail your inspection. That happened to a client of mine a while back who decided to install his own cable railing. Cable railing is a bit tricky, as a lot of my clients don’t realize that meeting railing code requirements can be trickier with cable than with other materials.
It’s not that cable deck railing code requirements are different from regular railing codes. However, because cables aren’t rigid like other infills, they can create a challenge in meeting a few requirements. As long as you understand these differences ahead of time though–and find the right system to install–there’s no reason why you can’t build a strong, safe railing that still meets code.
Specific Code Considerations Complicated by Cable Railing
Cable railing systems are designed to offer a low rail profile. Because of that, you’re dealing with narrower components. Aside from the cable balusters, often the posts and rails on cable systems are narrower, too. That could create some safety issues if you don’t plan ahead. Here are some code and safety considerations to keep in mind.
- Graspability: To understand graspability requirements, you need to understand the difference between handrails and guardrails. A guardrail is designed to prevent users from falling over the edge. A handrail, on the other hand, is designed to offer something to grab onto for guiding users. If the stairway on your deck has more than four stairs, you must have a graspable handrail. Generally, the very narrow diameter of the cable railing balusters makes them non-graspable, as they’re only 1/8 to 3/8 of an inch in diameter and, if they’re horizontal, they generally don’t have a normal top rail. As a result, if your deck has a stairway on it, you may want to add a handrail to your cable railing system. Simply extending your railing likely won’t be enough as the top rail won’t be graspable. Some manufacturers, however, offer vertical systems, and these generally will include a graspable top rail similar to that of a traditional picket system.
- The 4” Sphere Rule: The 4” sphere rule applies to all types of railing systems, but becomes complicated in the case of cable railing, as cables have a bit of ‘give’ to them. The flexibility of this type of railing means that without proper tension, it won’t pass the sphere test. The tension of the cable must be powerful enough to keep the cables from moving when a sphere is pressed against them.
- The Ladder Effect: The ladder effect isn’t a code issue, but it can be a safety issue. The ladder effect is unique to infills that run horizontal, and is based on the principle that when someone is presented with something that looks like a ladder, they’ll try to climb it like a ladder. This could pose a hazard for children and possibly pets, so if you’re concerned about child-safe balcony or deck railings, choose a vertical baluster system. The IBC does not limit the use of horizontal infills, however, and if you don’t have small children, this is likely a non-issue.
My client’s major problem with his cable railing was passing the 4” sphere rule. There was too much give in his cables, and because of that, the sphere was able to slide right through. It could have been an expensive error, but I was able to advise him on lower cost ways to resolve the issue without having to replace his system.
Staying Compliant With Cable Deck Railing Code Requirements
The materials you choose for your cable railing, as well as how you create tension, are going to be the main determinants in how likely you are to pass inspection. By making a few adjustments to your railing design, you can work within these codes and create a safe, inspection-approved system. Here are a few guidelines to consider.
- Follow Basic Codes: Probably the biggest mistake I see is individuals thinking railing codes only apply to traditional picket systems. Regardless of whether you choose horizontal cable or traditional vertical pickets, remember that the maximum deck height you can have without a railing is less than 30” above the ground. For any deck 30” or higher you must have a railing that’s at least 36” high. In addition, your balusters or infills must be able to support 50 pounds of applied weight per square foot.
- Choose Marine Grade Stainless Steel: The 4” sphere rule requires enough tension to prevent the ball from passing through. However, you’re definitely not going to stay compliant if your cables corrode, wear through, or stretch. Marine-grade stainless steel cable railing made using 316 stainless steel, rather than the more typical 304 stainless, ensure you’ll be able to pass the 4” sphere test for years to come.
- Choose a Cable System with Top Rails: As the goal of a cable railing system is a low railing profile, there are often only posts in these systems, with cables acting as the top and bottom rails. This is fine in instances where a handrail is not required, as guardrails have no graspability requirements. However, for outdoor steps, a safety handrail will give users a handhold when going up and down the stairs. In addition, if you’re designing for a public building or a multi-unit one, commercial building codes will apply and will almost always require a handrail.
While it’s possible to put a cable railing system together yourself, often code requirements and the unique challenges of cable make it easier to buy a system that’s guaranteed to meet code. That’s what my client did when he was replacing his infills. A few pre-assembled cable railing panels allowed him to finish off the job and finally pass his inspection.
He chose to go with a Fortress Railing cable system, which is one of the few systems available that makes use of vertical cables. The entire Fortress line of building products is developed with code requirements in mind, and their cable system is no exception. It comes in pre-assembled panels which are designed to meet code, minimizing the room for error and making installation easy. If you’re looking to install a code compliant cable railing system, you may want to consider one of their railings for the best results.