How the two differ in kind
Both fill the space between a top rail and the deck so that nobody falls through, and they solve the same code requirement in completely different ways.
BALUSTERS are simple: vertical members at a spacing, each carrying nothing but itself, fixed at top and bottom. The structure is ordinary, the trade is ordinary, and the cost is modest. What they cost you is the view, since a run of balusters is a visual barrier however slim they are.
CABLE RAILING trades that for transparency, and buys it with tension. Each cable is tensioned between end posts, and the important consequence is that those end posts do not carry one cable's tension but the ACCUMULATED tension of every cable in the run — a considerable horizontal force applied near the top of a post, trying to pull it inward and rotate it. That load is what people fail to design for, and its symptoms are familiar to anyone who has seen a tired cable railing: posts leaning inward, cables that go slack no matter how often they are tightened, and a run that sags in the middle. Almost always a post problem, almost never a cable problem.
The second thing cable has to satisfy is the infill rule while being PUSHED. Guards are required to prevent a sphere of a specified diameter passing through, and a rigid baluster either passes or fails that test on its spacing alone. Cables move: press between two cables and they spread, so the requirement has to be met under load, not just at rest. That is why cable runs need intermediate posts or spreaders at limited intervals, and why closer cable spacing and higher tension are both part of the answer.
The factors that actually differ
Show
| Cable railing | Balusters | |
|---|---|---|
| The view | Nearly unobstructed, which is the entire reason to choose it. | A visual barrier, however slim the members. |
| Structural demand | High and concentrated. End posts take the sum of every cable's tension as a horizontal load near their top. | Low. Balusters carry themselves; the posts resist only the code's guard loading. |
| Meeting the sphere rule | Under load, not at rest. Cables deflect apart when pushed, so spacing and free span are both limited. | By spacing alone, checked once and fixed forever. |
| Intermediate supports | Required at limited intervals to control deflection, and they are part of the design rather than optional. | Set by the rail's own span and by convention. |
| Climbability | Horizontal cables read as a ladder, and some jurisdictions restrict horizontal infill where children are expected. Check before setting posts. | Vertical members are the standard answer to that concern. |
| Cost | High — the hardware, the stainless cable, and posts strong enough to be tensioned against. | Modest, in any of a dozen materials. |
| Trade required | Careful work: drilling posts in line, terminating fittings correctly, tensioning evenly across a run. | Ordinary carpentry. |
| Maintenance | Retension after initial stretch and then periodically. Stainless can stain in coastal or industrial air and wants washing. | Whatever the material needs — painting or staining for timber, effectively nothing for composite or metal. |
| Damage and repair | A damaged cable is replaced through the whole run, and the run is detensioned to do it. | One baluster out, one baluster in. |
| Where it is wrong | A long run with light posts, or anywhere small children will use horizontal members as a ladder. | Anywhere the view is the reason the deck exists. |
Which one, and when
Choose cable railing when…
- The view is the point of the deck or balcony, and obstructing it defeats the project.
- The posts can be made strong enough, and their connections designed for the accumulated tension.
- The run is short enough, or broken by corners and intermediate posts, to keep deflection in check.
- There is budget for the hardware and for the structure that has to resist it.
Choose balusters when…
- Budget matters, which on a long run it usually does.
- Small children will use the guard, where horizontal infill is a climbing frame and may not be permitted.
- The work is being done by a general carpenter without specialist hardware experience.
- The railing is part of the architecture rather than a window onto something — a street frontage, a porch, an internal balustrade.
Now run your own numbers
This page holds no prices on purpose — a national average is wrong for almost every real project. Quantify both options with your dimensions and your local quotes.
Frequently asked questions
- Why do my cables keep going slack?
- Usually because the posts are moving, not because the cables are stretching — although new cable does bed in and needs retensioning once or twice early on. Each cable is tensioned between end posts, and every cable in the run adds its share to the same pair of posts, pulling them inward at the top. If the posts or their connections are not stiff enough for that total, they deflect: the distance between them shortens, and every cable in the run goes slack at once. Tightening them again simply pulls the posts further over, which is why the problem recurs and worsens. The tell is geometric — sight along the top rail and look for posts leaning inward, and check whether the slack returned across the whole run rather than in one cable. The fix is stiffer posts, better connections, or bracing, not more tension.
- How far apart can the cables be?
- Close enough that the sphere your code specifies cannot pass through them when they are PUSHED, which is a tighter requirement than the spacing alone suggests and the reason cable spacings are noticeably smaller than baluster spacings. Two variables control it. The first is the spacing itself, commonly around three inches or so, though your local code governs and it is worth confirming rather than copying. The second is the free span between supports: the further apart the posts, the more the cables deflect when someone leans on them, and two cables pushed apart can create an opening that would pass the sphere even though their at-rest spacing would not. That is why manufacturers specify a maximum spacing between intermediate supports, and why adding an extra post or a spreader mid-run is the usual remedy on a long straight.
- What do the end posts actually have to resist?
- The sum of every cable's tension, applied horizontally near the top of the post, plus the ordinary guard loading the code already requires. That accumulation is the point: an individual cable's tension is manageable, but a run of a dozen or more cables multiplies it into a substantial force trying to bend the post over and to rotate its base connection. The consequences are a design question rather than a site one — posts of adequate section, base connections that resist the overturning moment rather than merely holding the post down, and in some layouts additional bracing or a structural post carried down into the framing. Corner posts turning a run take load from both directions. This is where a cable system is engineered rather than assembled, and it is the part that specialist suppliers provide details for.
- Are horizontal cables allowed where there are children?
- It varies by jurisdiction and it is worth confirming before posts are set, because the answer shapes the whole design. The concern is straightforward: a series of horizontal members at regular spacing is a ladder, and a guard that a small child can climb defeats its own purpose regardless of how well it resists a sphere. Some codes address this with an explicit restriction on climbable horizontal infill in locations where children are expected; others leave it to the designer. Where horizontal cable is restricted or unwise, the usual alternatives are vertical cables, which run from the top rail to the deck and have their own tensioning arrangement, or conventional balusters, or a glass or mesh infill that gives transparency without footholds. Checking locally is a five-minute question with a large consequence.
- Will stainless cable rust?
- Not rust in the ordinary sense, but it can develop surface staining — a brown discolouration often called tea staining — particularly in coastal air, near pools, or in industrial atmospheres. It is a surface phenomenon rather than a structural one, and it is largely cosmetic, but on a bright new railing it is conspicuous. Two things reduce it: specifying a marine-grade stainless rather than the more common general-purpose grade in aggressive environments, and washing the cables periodically with fresh water so that salt and deposits are not left sitting on the surface. Where the staining has established, proprietary stainless cleaners remove it. The related point is fittings and fasteners: mixing stainless cable with fittings or a post of a different metal sets up galvanic conditions that accelerate corrosion at the junction, so the hardware should be compatible throughout.
- How much more does cable railing cost?
- Several times a conventional baluster railing in most markets, and the hardware is only part of it. The cable itself, the terminations at each end of every run, and the tensioners add up quickly per linear metre, and they are bought per cable rather than per length — so closer cable spacing, which the deflection requirement often demands, multiplies the count. Beyond the kit, the structure is more expensive: posts sized and connected for the accumulated tension are heavier than posts that only have to resist code guard loading. And the labour is specialist — posts drilled accurately in line, terminations made up correctly, and the run tensioned evenly. Where the view justifies it the cost is usually accepted; where the railing is not looking at anything, the same money buys a great deal of other deck.
- Can I retrofit cable into an existing railing?
- Sometimes, and the structural question comes first rather than the aesthetic one. An existing post arrangement was designed to resist guard loading, not to be tensioned against, so the honest starting point is whether the end posts and their connections can take the accumulated cable tension without moving. Often they cannot, and the retrofit means replacing or reinforcing the end posts and their fixings — at which point most of the cost of a new railing has been incurred anyway. The other constraints are spacing and span: the existing post positions may be further apart than the deflection limit allows, requiring intermediate posts or spreaders, and the top and bottom rails have to be able to accept the terminations. Where the existing structure is generous, it works well; where it is minimal, a retrofit is a rebuild.
- How do I know the sphere rule is satisfied?
- Test it, with something the size your code specifies, and test it under a push rather than at rest. For balusters it is a static check: offer the sphere up between adjacent members at several points along the run, including where a baluster meets a post and where the run crosses a change in level, which are the places spacing quietly drifts. For cable, do the same while pressing the cables apart with the other hand at midspan between posts, because that is the condition the rule exists for. Check at the middle of the longest free span, which deflects most, and at the top and bottom of the run where an oversized gap to the rail or the deck is a common oversight. It takes a few minutes and it is the check a building inspector will make.