Bar spacing on wrought iron work.

Bar spacing is an incredibly important part of any wrought iron design. But it’s often not thought about or over looked, and almost certainly not mentioned on many of internet retailers. As a manufacturer you have total control over the upright bar spacings.

This might mean on a gate designed to keep a small dog in, you can add in an extra upright. Thus decreasing the gap between each bar, so the dog can not squeeze through. But it’s equally important on a railing, that all bar gaps are even. That includes from the wall to the first upright, that gap should be the same as all the other gaps in the railing. Otherwise it looks like something cut from a longer railing to fit the gap.

Set size spacing, pros and cons

There is a case for set spacings and that is purely cost. Of course the spacings will only work for certain sizes. Imagine just being able to drop the upright bars into a tool or holder, that has preset spacing. Just drop them in the holder and weld them up. No time spent working out the spacings between bars, no time spent marking out where the bars should be welded. If you are making a one size fits all panel, then your upright bar spacing tool can be made to work perfectly.

When you allow the option of different length panels, its not always going to work. Your start and finish bars might have a different gap to the rest of the bars in your panel. But after all it’s mass produced and price conscience. The look won’t be as good, but it’s cheaper. So if working on a tight budget its usually an acceptable compromise. To be fair its surprising how many people don’t notice until you point it out.

The case for fully justified spacings

The case here is purely based on looks, but then isn’t that the reason people buy a wrought iron railing. Having spent a fortune on having a wall built, why would you compromise on the finish touch, the railing. All gaps being even, just has a really nice quality look to it. The downside is that it takes longer to make than a set space railing by quite a margin. First you have to do some calculations for your spacings. Or raise a CAD drawing with all details on (even slower). Then mark your spacings on the horizontal bar. Because each one has to be held in place and welded.

This is time consuming, can quite easily take twice as long compared to using a spacing tool with set sizes. All thing considered the material content is the same but twice as much labour. So obviously this is going to reflect on the price. As a rule this type of iron work tends to use thicker material than the set spacing type. Mainly because your are working on something that is more quality conscience that price conscience. Thicker material just looks better, but obviously comes at increase cost of materials.

Brickwork and bar spacing.

There does seem to be a theoretical correlation between bricks and bar spacing. A common UK brick size is 215mm long, the recommended cement joint thickness is 10mm. although most walls i have seen tend to have around a 12mm thick joint. In theory a brick wall, with a brick pier at each end, lets say 7 bricks between each pier. Would take 7 x 215mm for the bricks (1505mm) space. Plus 8 mortar joints at 12mm each (96mm). So around 1600mm gap between piers. As far as getting even gaps between bars one option would be 115mm centre to centre of uprights.

Trying the same with 10 bricks, gets a pier to pier size of 2282mm. perfect size here is 114.7mm. not far off the 115mm. So what about 4 bricks, gap size here would be 920mm. Perfect size her would be 116.5mm. That’s close but not perfect. 1.5mm inaccuracy that quite a lot. But this 4 brick space would only have 7 upright bars (8 gaps). 8 times 1.5mm is only 12mm, or off by 6mm each end. Not a massive amount and likely an acceptable compromise if it reduces the price.

So what happens when there is half a brick or a brick turned side ways does it still work? Dimension are listed as 102.5mm for a brick width. So 102.5mm plus a 12mm mortar joint adds another 114.5mm to the length. Down side is that whole bricks always produce a centre upright bar. A half brick means an even number of bars. This can sometimes cause issues when you want a decorative pattern in the railings.

Now when i say a 115mm, we are talking bar centre. So when using 12mm bar the gap or space between uprights is 103mm. So not excessively large. There are no rules for gaps between uprights on a wall railing. Unlike Juliet balconies or patio railings.

The boring maths part for getting even spacing.

For those interested it’s quite a simple bit of maths to get the perfect spacing on say a railing. Take the size you require, lets say for this example 1830 mm (6 foot). Add to that the thickness of the upright bar you are using, lets assume 12mm. The reason for this is because we are interested centre position of each upright, rather than physical gap. The centre position of your first and last bar will be half the thickness off the end of the bar (6mm each end).

Now take 1842mm, and divided by centre spacings you require. Lets assume you want a maximum gap between bars of 100mm. You need to add the upright bar thickness to that, so you would divide by 112mm (100mm + 12mm thick bar). This gives you a result of 16.44. Not being a whole number would mean uneven gaps at the end between the wall and the first, when compared to the rest of the bars. If you round the number up to 17, Then re divide 1842mm by 17 you now have 108.3mm (bar centres). take away your 12mm bar thickness and you have a gap between bars of 96.3mm

When you divided by 17, you are dividing by the number of gaps not the number of upright bars. Your bar count will always be one less than the number of gaps. So this would give you 16 upright bars. If you have decided you want a pattern in the railing and that pattern requires a centre bar, this spacing isn’t going to work. you now have a choice, if your 100mm gap between bars wasn’t that important then you can divide by 16. This would give 115.1 mm centres or a gap of 103.1mm on a garden wall railing gap is more about look. But on a patio railing or balcony it needs to follow building regulations. No gap larger than 100mm, So your only option there is to divide by 18. This gives a centre of 102.3mm with a gap between uprights of 90.3mm.

Specifics on gates.

Gates are a little different and slightly more complicated. Allowance needs to be taken into account for hinge gate and latch gap. On a single garden gate, usually about 115mm. So a 915mm wide gate the frame is 800mm wide. But you then need to subtract from that the thickness of the hanging and closing stiles. So if using 30mm x10mm for hanging and closing stiles. Your size for working you gaps becomes 780mm. 800mm minus two lots of 10mm. From there on it works the same. For double gates its usually 180mm from size for hinges and gap. Then divided by two to get the size of each leaf, Then minus your hanging and closing stile thickness. On Estate gates its normal to us 40mm hollow box as hanging and closing stiles.

Summary of maths.

(Railing length + upright bar thickness) / (required maximum bar gap + Bar thickness to be used) = number of gaps.
Number of gaps – 1 = bar count
(Rail length + bar thickness) / number of gaps = bar centres
Bar centres – bar thickness = gap between uprights