Perforated metal is a strong material despite the fact that the panel is punched right through with patterns. Its proven strength makes perforated metal a preferred material in many common load-bearing situations such as staircases, balustrades, balcony rails, flooring and fencing.

However, when using perforated metal in applications that demand robustness, one needs to carefully consider the many different factors that can affect panel strength.

Arrow Metal has put together a few useful tips to help you understand more about using perforated metal for strength and style in your project, and specifically which profiles to consider for the sturdiest solution.

How strong is perforated metal?

The strength capabilities of your finished perforated metal panels depend on a combination of several factors:

Open area

Open area relates to the amount of open space that the punched holes create in the panel. The bigger the percentage of open area in the panel, the less solid it is, and therefore, the ‘weaker’ the panel will be. For example, let’s compare profiles P224 and P239, which both have the same round hole shape and a staggered pitch. If you were to choose the best perforated metal for strength between these two profiles, P224 would be the strongest. This is because the holes are smaller and spaced out, creating only a 10 percent open area. In contrast, P239 has a much greater open area of 58 percent. The holes are large and close together, which means that there is much less solid area between each hole.

Hole shape

Together with open area percentage, your choice of hole shape makes a difference too. Complex, delicate, and intricate varied patterns on a single panel could compromise panel strength.

Metal choice

Your choice of base metal is a key factor as some metals are inherently stronger than others.

Installation setting

Some pattern profiles may even have different strength properties depending on whether the finished panels will be folded or bent for installation. A round end slot pattern, for instance, should ideally be bent or folded along the length of the slots to maintain strength. 

Which patterns are best when specifying perforated metal for strength?

Now that you know more about what affects the strength of a perforated metal panel, here’s some general advice to bear in mind when considering perforated metal patterns. It’s a good idea to look for:

A profile with a low open area percentage

Profiles with a high open area percentage will not be suitable for strength purposes because there is too much open space created by the holes. So once you have found a pattern you like, check the open area percentage of the available profiles. Most standard patterns come in a choice of open area percentages, so you can easily find one that optimises strength but still gives you the aesthetic result you want to achieve.

A uniform pattern arrangement

Perforated metal allows you to arrange the pattern holes to your design preferences. So if you are using perforated metal for strength, stick to even spacing such as a 60-degree staggered pitch arrangement, which is considered to be one of the best hole layouts for strength.

A round hole pattern

Round holes are classic but they are also one of the strongest hole shapes you can choose, above rectangular or round-end slots.

Stainless steel or steel base metal

Aluminium is a hugely popular metal to perforate but if you want the strongest result, choose stainless steel or steel. A 3mm thickness panel in stainless steel will be stronger than a 3mm thickness panel made from aluminium. But if you must have aluminium, remember that different grades do offer different strength properties.

Summing up...

So finally, what is a good perforated metal profile for strength? Based on the above, consider a steel or stainless steel panel, perforated in a round hole pattern in a staggered arrangement, with a low open area percentage.

Such as pattern P222, which has small 3.2mm holes and a 10 percent open area. Or pattern P241 if you need larger holes – P241 has holes of over double the size (8mm) of P222, but still only a 16 percent open area.

Regardless of which pattern style you prefer, we do advise that it is always best to consult a structural engineer before you order your panels to ensure that you specify the most suitable profile – be it a standard in-stock profile, a made-to-order panel or a customised solution.

Whatever your strength requirements, at Arrow Metal we can manufacture bespoke perforated metal panels to your exact specifications for a safe and strong result that achieves all your aesthetic and budget requirements, too.

Image: Perforated metal pattern #224