What Makes Anodized Aluminum Dock Sections Different?

Posted by Alumi-Span Docks on 3/3/2020
Anodized aluminum dock sections are one of the best options for a dock system. The combination of light weight, high strength, cool to walk on, and easy stack-ability make this dock design. Alumi-Span pioneered this type of docking system in the early 60’s.  After developing a leg system to use in the late 50’s on a type of wood decking, eventually the aluminum dock section was born and even received Alcoa’s “Aluminum Product of the Year” Award. Original designs used a type of aluminum scaffolding plank.  Ultimately the design was further improved by using an “F” side stringer.  The now standard 4-inch-tall “F” channel side rail can be found on many different dock systems today.  It is still one of the more dominate designs in the industry.


Modern Anodized Aluminum Dock Sections

There is a lot more than meets the eye when you start comparing anodized aluminum dock sections.  Alumi-Span has very strict quality standards.  The aluminum alloy, extrusion design, fasteners, and even the quality of anodizing used in the sections play a part.  If a manufacturer goes cheap on any of the things listed above, it can make for a very weak, noisy, or even a hot dock section.  Like all things for sale, there are low-end and high-end dock sections.  You need to take more into consideration than just the selling price when buying a dock. 

Aluminum Extrusions Wall Thickness

The wall thickness of the aluminum extrusions on a dock section play a major role in the quality of the sections and the strength you will get out of them. Many of the sections on the market currently use extremely thin decking board extrusions, as well as very thin-walled side stringers.  Some of them try to make up for this by placing additional aluminum beams down the back of the decking.  Many of these sections are as much as 30% weaker than a similar Alumi-Span section, so buyer beware.  The absolute weakest sections on the market are usually the welded variety with one or two beams welded to the bottom.  Their extrusions are paper thin.


Aluminum Alloy and Why It Matters

An aluminum alloy is the actual chemical makeup of the aluminum being used in your dock section.  We won’t get too technical here, but there are major differences between alloys.  Common basic aluminum alloys used in the dock industry are almost all of the 6,0XX series.  There are structural alloys and non-structural alloys of aluminum in the 6,0XX series.  A common non-structural alloy would be 6063-t6.  This is good for things like upright legs and decorative type accessories. It is not good for side rails and deck boards.  There are plenty of companies that use this for everything; it is cheaper.  A much better choice for the decking application would be 6061-t6.  This is a structural alloy.  It is roughly 35% stronger than the 6063-t6.  There are many other alloys that can be used that are structural and there are also different heat treatments (the “t6” is a heat treatment designation).  That subject is beyond the scope of this article.  Long story short: If you find someone that is using 6063 aluminum alloy on a dock section, run fast and far away!

Different Aluminum Dock Construction Styles

There are two main ways to build an aluminum dock section: welded and non-welded.  There are a couple higher-end companies that weld their dock sections together, but the majority of welded aluminum dock sections found are on the very low-end. 

Non-welded sections generally have a deck board with some sort of hinge in the edge of it, so it can lock onto the one next to it.  This eliminates the need to weld everything together in most cases.  It can also be much stronger and quieter. 
If a company is welding their dock sections together, it isn’t because it is stronger.  In most cases, they have to weld beams down the back of the decking because the boards don’t lock together.  Without the under support, the decking would collapse.  Most companies building like this also have some of the thinnest deck board extrusions in the industry, so welding beams to the section is almost always out of necessity.  Welded sections, especially cheap ones, are extremely noisy and usually some of the weakest sections on the market.  The thin extrusions dent easily too.

Non-welded sections that have a hinge in the decking are the way to go.  There are still alloy and extrusions thickness issues on the low-end, but generally these sections are much better built.  The higher-end versions of this decking will incorporate some sort of filler or padding into the hinged part of the decking.  This makes them much quieter to walk on than a welded dock because there is no metal to metal contact.  Alumi-Span dock sections have outdoor rated sub-floor adhesive injected into the hinge when they are built.

This makes them really solid and almost dead quiet.  Don’t purchase a dock without something embedded in between the metal to metal contact points.  It will be noisy.



Not all dock sections are created equal.  Buying from a company that has been in business for many years is advisable.  You also need to do your homework.  There are new startups in the industry all the time and some of these manufacturers are cutting every cost possible.  There is some real garbage on the market these days. 

  • Quality made anodized aluminum dock sections will use a structural aluminum alloy and a relatively heavy wall thickness on their aluminum extrusions.
  • Be wary of cheap welded dock sections. These are the lowest cost options on the market and also the worst performing products on the market. Some of them are dangerous. 
  • Price can tell you a few things and picking the ultimate low bidder on anything is a bad idea. That being said, keep in mind that many manufacturers are selling factory direct. This cuts out the middle man. A factory direct dock section in the mid-range price point could be just as good, or better than some of the more expensive brands at a Marina.

For more information on any of the topics discussed above contact Alumi-Span Docks for expert guidance and recommendations.