There is no generally prescribed post spacing that applies to all railings. However, there are requirements regarding what the railing must be able to withstand, and the distance between posts are one of the factors that influence the design.
The dimensions and fixings of the profiles are two other important factors. If you change one of these parameters, it also affects what is possible for the others.
Therefore, there is no single standard that applies to all railings. The appropriate post spacing depends on the type of railing, the infill, the material, the load, and how the structure is anchored.
Why isn't there a standard post spacing specified in the rules?
The load-bearing requirements for a railing depend on its location and how it is used. There is no standard c/c dimension for all railings. Post spacing, profile dimensions, and fixing must therefore work together, and different balustrade systems may have different permissible section widths.
If the distance between posts is increased, the rest of the structure must still be able to withstand the applicable load. This can affect, for example, the post profile, infill, glass dimensions, and fixings.
Two load levels you'll encounter in our balustrade systems
The usage classes are Balustradedesign’s own guidelines, based on factors such as product testing and the configuration you choose. They do not describe all load requirements that may apply to different usage environments.
Our Class A railings can withstand a horizontal line load of at least 0.5 kN/m.
Our A+-rated railings can withstand a horizontal line load of at least 1.0 kN/m.
What is the typical post spacing for different types of balustrades?
For many post-mounted railings, approximately 90–120 centimetres is used as an initial design guideline, but this is not a general maximum dimension. The permissible post spacing depends on balustrade system, infill, height, fixing, and load, and must always be verified against the technical documentation for the selected design.
What determines the maximum distance between posts?
The post spacing is determined by how the entire railing structure functions as a whole. The infill, post profile, fixings, balustrade height, load, and wind exposure can all affect the possible section width.
Glass balustrade with posts
In a glass balustrade , the section width must work in conjunction with the glass dimensions, the post profile, balustrade height , and fixing. A greater distance between posts means that the glass and other components have a longer span over which to bear the load.
glass balustrades, a railing store, uses laminated safety glass to hold the panel together if the glass breaks. The required glass dimensions depend on the specific balustrade system and configuration.
Wire balustrade
In a wire balustrade, the stiffness of the posts, the tension in the wires and the fixings determine the possible section widths. The longer the unsupported span, the more important it is that the whole system is designed for it.
The tension of the cables should be checked regularly and readjusted as needed. If the cables become too slack, they may deflect more under load, causing the openings to change.
Bar balustrade made of aluminium
Factors such as the post profile dimensions, balustrade height, and fixing influence how wide the sections can be. A sturdier system may be designed for different section widths than a slimmer system.
The fixing is also crucial for transferring the load from the posts to the supporting structure. Therefore, it is not enough to determine the post spacing based solely on the profile.
Slatted fence
A slatted fence has denser infill than many open balustrades and may therefore be subject to greater wind loads. The fence height, the design of the slats, the post profile, and the fixing must be evaluated together.
Wooden and aluminium posts have different properties and should not be compared solely based on the same c/c dimension. The technical specifications for the specific design in question should serve as the guiding principle.
What happens if the distance between the posts is too great?
Excessive post spacing can make the railing more flexible and increase deformation in posts, the infill, and fixings. How noticeable this is depends on the railing system’s design and the loads to which it is subjected.
Therefore, the post spacing should not be evaluated in isolation. The profiles, infill, and fixing must all be dimensioned together for the section width being used.
Posts and the railing can move more
As the sections become wider, the structure has a longer span between support points. This can make the movement more pronounced and, at the same time, affect the load on the posts and fixings.
The glass can bend more
In a “ glass balustrade ,” a longer unsupported span can cause greater movement in the glass pane when under load. Therefore, the glass dimensions, posts, and section width must be coordinated with one another.
The wires may deflect more
In a wire balustrade , the free length determines how much the wires can move under load. If the wires are also too slack, the openings may change more than intended.
Are post spacing and opening dimensions the same thing?
No. Post spacing refers to the distance between the balustrade posts, while opening dimensions refer to the clear space within the guardrail itself or the infill. These dimensions affect different aspects of the railing’s function and should not be confused.
Determines the span of the structure
Post spacing is often specified as a c/c measurement—that is, from the centre of one post to the centre of the next. This spacing affects, among other things, the section width, stiffness, and how the load is transferred through the railing.
Describes the free space
The opening dimension is the clear space within the guard, for example, between two vertical bars. In this case, the rules are based on preventing children from falling through or getting stuck.
What should you check when determining the post spacing?
Start by determining the railing's dimensions and fixed points, distribute the sections evenly, and then verify that the infill, profiles, fixing, and site conditions are compatible with the chosen layout.
Here's what you should check
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Have you measured the entire length of the railing?
Measure the total length that the railing will cover at the location where it will actually be installed. Use that measurement as a basis before determining the number of posts or sections.
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Are the corners, ends, and joints positioned first?
Start with points that have a specific location. That way, you'll see how much distance remains between corners, ends, and connections, and you'll be able to distribute the remaining posts more effectively.
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Will the sections be evenly distributed?
Divide the remaining length so that the sections are as evenly proportioned as possible. Small adjustments across several sections usually create a more balanced look than a single section that is much narrower or wider.
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Is the infill suitable for the planned section width?
Glass dimensions, wire systems, slats, and other infill materials must be adapted to the clear span between posts. The post spacing therefore cannot be considered a standalone measurement.
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Are the post profile and fixings correct for this design?
Posts and their fixing must be able to transfer the load to the supporting structure. Therefore, check the profile and fixing along with the cross-sectional width you are planning.
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Is the balustrade suitable for the environment in which it will be used?
The railing must be designed to withstand the load at the installation site. Verify that the selected system and configuration are suitable for the location.
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Is the location particularly exposed to the wind?
An open, elevated, or coastal location may be more exposed to wind. This is particularly significant for glass and denser infills and can affect the possible section width.
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Have you checked the opening dimensions separately?
Post spacing and opening dimensions are two different things. Therefore, be sure to also check the clear openings in the railing infill without confusing them with the c/c measurement between posts.
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Does the section layout match the technical specifications for the balustrade system?
Finally, verify that the section widths, balustrade height, fill, and fixings are within the specifications for the selected system. General guidelines should not be used as the sole basis for design.
The goal is evenly spaced sections—the technical specifications set the limits
Feel free to distribute posts so that the railing has even proportions, but never use a section width greater than what the relevant balustrade system is designed for.
Which railing is right for your balustrade run and the site conditions?
The post spacing is determined based on the balustrade system, dimensions, and fixings. Start by selecting a railing type, or contact us if you’d like help assessing your layout before placing an order.
What are the most common questions about post spacing in balustrades?
The most common questions concern what distance is considered normal, what happens if the sections are too wide, and how the post spacing differs from the rail opening dimensions.
Is there a legally mandated distance between posts?
No, there is no generally prescribed post spacing that applies to all railings. Instead, the design must meet the requirements specific to the location, and the distance between posts must be adapted to the design and technical specifications of the chosen railing system.
What is a typical distance between posts?
Approximately 90–120 centimetres is often used as an initial planning reference for post-mounted railings, but this is not a general maximum dimension. The actual section width depends on balustrade system, infill, height, fixing, and load, and must always be verified against the relevant technical documentation.
What happens if the distance between the posts is too great?
If the distance is too great, it can cause greater movement in the railing and increased deformation in posts, the infill, and fixings. In glass balustrades, the glass panel may move more, and in wire balustrades, wires may give way more. Noticeable sway is therefore a reason to check the design against the system’s technical documentation.
Does the wind affect the distance between posts?
Yes, exposure to wind can affect the possible section width, especially for glass and denser infills. An open, elevated, or coastal location may therefore require a different configuration than a more sheltered location.
Are post spacing and opening dimensions the same thing?
No. The post spacing describes the distance between the railing’s posts and is often specified as a c/c measurement. The opening dimension describes the clear space within the railing’s guard or infill, for example, between vertical balusters.
What type of glass is needed for longer spans?
It depends on the design of the specific glass railing. A longer unobstructed span can affect the required glass dimensions, post profile, and fixing . Balustradedesign’s glass balustrades use laminated safety glass , and the correct glass dimensions are selected based on the specific system and configuration.
Do the same post spacing rules apply in a staircase as they do at home?
Not necessarily. The load for which the railing is designed depends on the environment in which it will be used, and public or high-traffic environments may have different requirements than a private residence. This can affect section width, profiles, infill, and fixings.
