How to Tighten Deck Cable Railing

Maintaining proper cable tension is essential for the safety, appearance, and long-term performance of Trex^® Signature^® X-Series™ Cable Railing. After initially being tightened, stainless steel cables naturally stretch and slightly relax over time. This is normal, which is why cable railing systems may require a couple of rounds of adjustment early on. Over time, the cables stabilize, and ongoing maintenance becomes minimal. One of the key advantages of the Trex Signature X-Series Cable Railing system is that its purpose-built components make both initial installation and long-term cable maintenance simple processes that require basic skills and very few tools.

Disclaimer: Instructions provided by Trex® are based on the build specifications that Trex® demonstrated in the Trex® Academy video series and are not universal to all homeowners’ projects. A homeowner’s build may vary from Trex’s instructions based on the homeowner’s local municipality requirements, individual design preference and project specifications. For questions or assistance needed during your project, please reach out to howto@trex.com.

Step-by-Step Instructions

01: Identify the Tensioning Mechanism on Your Cable Railing System →
02: Tighten Your Railing Cables in the Correct Sequence →
03: Preventing Future Cable Loosening →

Jump to chapter:

Chapter 01: Identify the Tensioning Mechanism on Your Cable Railing System

Chapter 02: Tighten Your Railing Cables in the Correct Sequence

Chapter 03: Preventing Future Cable Loosening

Photograph pointing out connections and turnbuckles for cable railing

Before you begin tightening your cable rails, it’s important to understand how the system works and the key components involved. Many other cable railing systems rely on multiple mechanisms that must be adjusted during tensioning, whereas the Trex Signature X-Series Cable Railing system requires attention to just these two components:

1. Turnbuckle: This is the only moving component in the system. Rotating the turnbuckle increases or decreases tension in the cable.

2. Push-to-Connect Fitting: This proprietary component is one of the features that makes the Trex Signature X-Series Cable Railing system simple to install. During initial installation, the long end of the cable is pushed into this fitting, which securely holds the cable in place without the need for additional fastening hardware like set screws or crimp rings.

Tools Required

Two turnbuckle wrenches (Optional): One wrench is included in every cable railing section kit. If you no longer have them, you can still tighten the cables using standard hand tools.
A 3/8-inch open-end wrench or an adjustable wrench: Required to hold the Push-to-Connect Fitting if you no longer have the Trex-supplied turnbuckle wrenches (more on this below).
Pliers: Pliers can be used to turn the turnbuckle if you no longer have the Trex-supplied turnbuckle wrenches.
A 3/32-inch Allen wrench: Used to realign the cable brace, if necessary.

Painter’s tape: This can be wrapped around the turnbuckle to prevent the pliers from leaving scratch marks.

Inspect All Fittings and Cables

Before any tightening begins, perform a full inspection of the system. Look closely at each cable run and fitting to ensure there is no visible damage. Frayed cables or bent hardware should be replaced before tension is applied.

How to Tighten a Railing Cable

Photograph demonstrating process for tightening cable railing

When using Trex turnbuckle wrenches:

Hook one side of the turnbuckle wrench onto the Push-to-Connect fitting on the cable that is going to be tightened. Connect the other end of the wrench to the Push-to-Connect fitting on the cable either above or below that one.
Use the center of the second turnbuckle wrench to rotate the turnbuckle. If you imagine yourself standing with your back against the nearest post, you’ll want to turn the wrench clockwise as you see it in front of you.

If you don’t have the Trex turnbuckle wrenches:

Wrap painter’s tape on the turnbuckles or the jaws of the pliers to prevent scratching the finish on the turnbuckles.
Use a 3/8-inch open-end wrench or an adjustable wrench to hold the Push-to-Connect fitting in place.

Use pliers to rotate the corresponding turnbuckle. Again, if you imagine yourself standing with your back against the nearest post, you’ll want to turn the wrench clockwise as you see it in front of you.

Photograph showing gauge measuring cable railing tautness

Verify Tension with a Gauge

The more you rotate the turnbuckle, the more tension is applied to the cable. The most accurate way to achieve the correct tension on each run is by using a cable tension gauge. These tools are easy to use, simply hook the gauge onto the cable and tighten the turnbuckle until the gauge reads the specified value.

For Trex Signature X-Series cable railing, the proper tension is 100 pounds per cable. The gauge shown here measures tension in kilograms only, so 100 pounds must be converted to 45.36 kilograms. IMPORTANT: Accidentally tightening the cables to 100 kilograms instead of pounds could damage the posts or cause the Push-to-Connect fittings to fail.

A gauge like the one shown costs about $130, and some digital gauges can cost more than $1000. Unless you’re a professional installer, that might be more of an investment than you want to make. If you don’t have a tension gauge, one rule of thumb is to…(what?)

Photograph showing order of tightening for cable rail installation.

Tension the Cables in Sequence

When tensioning a cable railing system, always start with the center cable and work outward in an alternating pattern, tightening the cable below the center, then the one above it, and continuing this sequence until you reach the top and bottom. This approach helps balance the load on the posts as tension is applied. Tightening the center cable first can cause the post to flex very slightly under load. If the center cable were tightened last, that small amount of movement in the post could slightly loosen the cables above and below the center. After working outward, return to the middle cables and recheck their tension to ensure they all remain evenly tightened.

Check the Cable braces

Tightening the cables can cause the cable braces to move slightly out of plumb or off center. Check the distance between the posts and brace on either side of each brace. The distance should be the same in both directions at the top and bottom of the brace. If a brace is out of alignment, use a 3/32-inch Allen wrench to loosen the set screws at the top and bottom of the brace, and reposition it as needed.

While it isn’t possible to completely prevent cable railing from relaxing over time, you can minimize excessive slack by tightening the cables under moderate temperature conditions. Stainless steel cables expand in hot weather and contract in cold weather. If cables are tightened on a very cold day, they may loosen naturally when temperatures rise. Conversely, tightening cables on an extremely hot day can cause them to contract as the weather cools, potentially placing excessive stress on the posts and fittings. For best results, adjust cable tension when the outdoor temperatures are moderate.

Another way to reduce the likelihood of loose cables is to replace any damaged runs only with Trex cable and components. Using lower-quality cable can result in uneven stretching, causing one cable to lose tension faster than the others and making consistent adjustment more difficult.

For More Information

The high quality Trex stainless-steel components are engineered to resist oxidization, corrosion, and discoloration while the streamlined tensioning system makes installation and periodic adjustments straightforward. When properly installed and maintained, Trex cable railings provide a safe, code-compliant solution and are backed by a 50-Year warranty.

Learn more about Trex cable railing options and resources. For help with installation or maintenance, connect with a TrexPro®^®.