Bar spacing and gapping.
Bar spacing is a crucial element in wrought iron work. There are two main approaches, and neither is inherently right or wrong. The “fixed” spacing method is faster and simpler to execute. On the other hand, the “variable” or “justified” spacing takes more time but results in a more polished and visually appealing finish.
Fixed spacing is classified as economical primarily because it is significantly faster and more efficient to construct compared to justified spacing wrought iron work, which tends to be more time-consuming and complex in its fabrication process. Below is a brief explanation of what we mean by fixed spacing and variable or justified spacing.
Fixed spacing method
This is one of the most common methods used by online suppliers of wrought iron railings. Typically, website descriptions mention a 100mm spacing between bars or bars spaced at 100mm. This means there is a 100mm gap between each upright bar. While this sounds straightforward, it can lead to issues. Specifically, the gap between the wall and the first upright bar, as well as between the last upright bar and the wall, may not be 100mm. No one mentions that part
In fact, the gap between the wall and end bars depends heavily on the length of the metal railing. It results from the leftover space after calculating the railing gaps. It is very rare for a railing length to divide down perfectly. This gap will never exceed 100mm and is typically smaller. With the minimum usually being 45mm.
Why use this method of spacing? The answer is simple: speed of construction. With a bit of skill, the right tools, and some time, you can easily create a spacing tool. This tool lets you quickly and easily position cut upright bars, making them ready to weld without any complex calculations. Just ensure that the end bars have equal gaps relative to each other. Making a high quality and accurate spacing tool takes time. But once made it can be used over and over again to produce consistently accurate spacing between upright bars
This also provides access to pre-manufactured parts, many of which are designed for use in a 100mm gap. Components such as scrolls and rings, being pre-manufactured, are more affordable than custom-made parts. Therefore, the fixed spacing method is clearly the most cost-effective option.
Variable or justified spacing method.
I call it variable because the spacing between bars changes as the railing size changes; essentially, it adjusts all the spacing, similar to how a word processor justifies text.
This method is considerably slower because it involves manually marking the position of each upright in the wrought iron railing to achieve evenly spaced and justified bars. Essentially, you first determine the maximum allowable gap between uprights, then use calculations to find the precise spacing. For instance, instead of a 100mm gap, you might end up with 96mm, depending on the railing’s length. Changing the length of the railing alters the spacing, which makes the gaps between bars variable. However, the gap remains consistent from the wall to the first upright and continues uniformly throughout, including at the end. This variability prevents the use of a standard gap tool for the bars, resulting in significantly longer construction times compared to fixed spacing methods.
Visually, it appears far more impressive than fixed spacing, and you often exclude pre-manufactured parts simply because your gap ends up less than 100mm. The biggest downside, of course, is the significantly increased construction time—often by as much as 50%. It’s close to perfection, but it comes at a cost.
In a market where price is often the primary concern, very few online manufacturers use this method. They are consistently undercut on price by those employing the faster fixed spacing technique. Since this process is rarely explained, customers might assume they are comparing like for like.
Just to show the difference between the two, move the slider and watch the results change
This assumes the maximum allowable gap between bars using the justified spacing method is 100mm. If the gap exceeds 100mm, an additional bar is added, and the gap is recalculated, resulting in a smaller spacing. With fixed spacing, as soon as the gap between the end bar and the wall exceeds 100mm, an extra bar is inserted and the spacing is recalculated accordingly.
notes
While it is possible to create multiple spacing tools for various bar spacings, the cost of materials and time investment is significant. The 100mm spacer tool alone cost nearly £100 in materials, made from steel with aluminium spacer blocks. Although I never tracked the exact time spent, I estimate it took at least 5 to 6 hours to make. This may seem lengthy, but since the tool is reusable, the focus was on achieving maximum accuracy.
To cover a wide range of sizes, each pair of spacer tools should be made in 0.5mm increments, spanning from 100mm down to 90mm apart. This would require producing 20 tools. While it may never be perfectly precise, it would achieve a close fit, with only about a 5mm or 6mm variance at the end bar—likely imperceptible. The main challenge lies in the cost of materials and the time needed, as well as recouping that investment.
More details to be added in future updates