Aluminium is light but strong, which is why it’s used so much in aircraft. People are often surprised to learn just how thin the fuselage is though. In many places it’s only 1.00 mm thick. That’s about half to one third the thickness of aluminium copings. So why the difference, and how thick do aluminium copings need to be?
Different Grades and Compositions
Aluminium alloys vary a lot depending on composition. The grades used in aircraft are the strongest and most fatigue-resistant and, of course, that’s reflected in their price. Aluminium used in architectural fabrications like copings and fascia pieces, which is usually marine grade. It’s around two-thirds the strength of the aerospace alloy but offers excellent corrosion-resistance at a lower cost.
Of relevance to aluminium fabricators like ourselves, the marine grades are easier to work with. If a client were to specify aerospace grade alloy for their aluminium wall copings, they’d pay more for the material and more for the forming work.
Loads on Aluminium Wall Copings
Wall copings aren’t subjected to large pressure differentials the way a fuselage is, but they can experience surprisingly high loads. The main reason is wind. Winds blow stronger higher up and can gust around walls in unexpected directions – even vertically upwards! This is why our Secret Fix copings are wind-tested up to 144mph.
Winds that are strong impose high loads on the copings. If not appropriately secured, there’s a risk of them separating from the wall, with potentially very serious consequences.
The most likely failure mode is the coping pulling through the fasteners. That’s why it’s important to use aluminium coping of sufficient thickness.
Aluminium cappings, which don’t project over the wall like a coping, don’t experience quite such high loads. All the same, it’s important that they too are fastened to the wall appropriately and are thick enough to avoid pull-through.
Appearance and Performance Issues
Aluminium copings are usually formed with either an inclined flat top or domed for water run-off. However, as those experienced with aluminium fabrications will know, very thin sheets of the metal tend to ripple. When formed into copings, large flat areas made from sheet that’s too thin would have a wavy, uneven appearance. This looks unattractive and could lead to water pooling.
Ideal Thickness of Aluminium Copings
Minimum thickness of the aluminium coping depends on size of flat area. Design manuals for architectural fabrications suggest a thickness of 2.00 mm for coping widths up to 550 mm and 3.00 mm for those stretching to 650 mm. Remember though that these are guidelines. If you need something different, Contact Us for a discussion.
Thicker Than 3.00 mm?
There may be situations where thicker material is needed, but they are few and far between. And while it might seem that more is always better, thicker material is harder to cut and form. Not only will you pay more for the extra material, but you’ll also be paying for the work involved in making your coping.
Talk to the Aluminium Coping Experts
We have been producing aluminium fabrications for many years. We understand the material and how to get the best from it. If you have any questions about aluminium copings or related products, we’d love to hear from you. Call 01905 454790.
