Hollow Composite Decking (Everything You Need to Know)


Hollow composite decking is a less common profile than traditional solid and even scallop boards. But is gaining popularity, especially in the European market.

There are 2 common hollow designs, hollow tube designs and squares.

End cut of hollow composite decking

Despite both being hollow they do perform differently and are not equal in design. We will get a little more into that later but let’s start with what brands make hollow composite decking. Then answering some key questions related to hollow composite decking to help better understand it before installing it on your deck. 

What brands make Hollow Composite Decking?

None of the big brands of composite deckingOpens in a new tab. make hollow composite decking but rather choose to scallop the bottom of their economical lines.

That does not mean it’s a poor design. Just different approaches by different companies.

Brands that make hollow composite decking are.

  • Cladco Decking
  • Composite Prime
  • Dino DeckingOpens in a new tab.
  • Duxxbak (Rice Hull)
  • Genova (PVC)
  • TruNorthOpens in a new tab. (Tru Econo line)
  • Neotimber
  • NewTechWood
  • Zometek (Bamboo)

And the list is growing.

An interesting thing about this list is it includes non-wood-based composite decking. Material like bamboo, and rice hulls which in themselves are innovations in composite decking.  

The list of materials used to make composite deckingOpens in a new tab. is itself growing. Gone are the days of only having solid wood-based composite to choose from.

But back to hollow composite decking.

Is hollow or solid composite decking better?

There are both pros and cons of hollow composite decking compared to solid.

Reason why hollow is the better design.

Along with disadvantages of hollow composite decking.

Let’s start with the pros and then turn to the cons of hollow composite decking.

Pros

  • Economical
  • Lighter to work with
  • Reversible
  • More Stable
  • More Rigid

Similar to scallop boards hollow composite boards are cheaper. With the reduction of material from 30 to 40% means you are paying less for material and often forgotten shipping. If it weighs less, it cost less to ship.

Closely related is they are lighter and easier to move around. The reduction of material makes lighter work of hauling the boards to the deck substructure while you are building your deck. Often changing moving the deck from a two-person task to one.

Not embraced by all hollow decking brands but NewTechWood for example has two different finishes. Allowing you to flip the boards for a different feel to your deck.

Stability and rigidity are a little more debatable but are logical.

Debatable in that there are so many things that go into making composite decking that it is not consistent in impact.

But by further engineering the boards there is less material reducing the amount of movement with temperature changes.

And ironically, the hollow tubes actually reinforce the decking. It’s a shape thing but who would have thought that less material would make something stiffer, but it does.

Fortress has a similar claim with their I-series decking which is neither traditional hollow or scalloped but a combination creating “I” joists strengthening the decking.

Some hollow pros are debatable. Some suggest they are an advantage but are they really? That’s up to you to decide.

Hollow cavities in decking for running wires. Lights and speakers can really enhance your deck. One of the challenges is feeding the wires around the deck. Which often includes drilling holes in the joists. But with hollow decking, you can simply feed the wire through the decking. Saving you time drilling holes.

Deck boards are cooler with the air cavities inside the boards holding less heat. Hollow boards being cooler makes sense theoretically but often is not the case in reality. There have been many tests done by many individuals and companies and most conclude the most significant impact on temperature is colour.

But it may be worth setting up a sample of solid and hollow composite deck board in the colour you like in the backyard on a sunny day and see for yourself. If it is cooler to the touch.

Cons

  • Weaker

Before you accuse me of talking out of both sides of my mouth. Yes, hollow composite decking is both more rigid and weaker.

Part of this is because there are multiple generations and styles of hollow decking.

Earlier versions of hollow composite decking were too hollow. With not enough material left to prevent puncture. A common problem.

Damaged hollow composite decking

The shell of the composite decking would break from impact. This can still be the case with some square hollow composite decking. The unsupported area of the decking is too large to absorb impact, thus breaking.

Tube or Cylinder styles hollow decking are less likely to be damaged by impact.

A good example is with Composite Prime decking. Their square hollow boards only have a 10 years warranty but their cylinder lines are 25.  

Do remember that when you are shopping for hollow composite decking look for brands that are code approved to span 16” (400mm). The standard for decking.

If the decking can span 16” (400mm) without significant problems, then you should not have major strength issues with the decking.

How long does hollow composite decking last?

Current composite decking is designed to last 25+ plus years.

Earlier versions of composite decking often were weaker than solid composite and did not last as long. But now many hollow composite decking comes with a 25-year limited warranty. Like the brands below.

  • Composite Prime
    • HD Deck® Dual
    • HD Deck® Pro.
  • NeoTimber
  • NewTechWood
  • TruNorth
  • Zometek

Some brands should last even longer and have lifetime warranties.

  • DuxxBak        
  • Genova

But there are still hollow composite brands with shorter warranties, like the following brands.

  • Cladco
  • HD Deck® XS,
    • HD Deck® 150
    • HD Deck® 3D;
  • Dino Decking

I will explain more when discussing fixing composite decking but most of these warranties are limited in nature. Fading and staining are limited to a degree of colour change. Structural is not comprehensive but limited to manufacture.

But if installed correctly according to to manufacture instructions you can expect most hollow composite decking to last a long time.

If all this warranty talk has you wondering, who has the best composite decking warranty? Click the link to find out. Hint is not hollow but has more to do with the brand than the decking profile.        

What type of composite decking is best?

There are many types of composite decking, but from my research, there is not one type of composite decking that is best. But there are many brands of composite decking which are some of the bests. Click the link to see which brands are some of the bests with better performance. 

Is all composite decking hollow?

Most composite decking sold in North America is either solid or scalloped with only a few brands of composite manufacturing hollow decking.

In Europe, this is slightly different with many brands of composite decking offering hollow composite decking.

So it really is a regional question if you can buy hollow composite decking.

How do you fix hollow composite decking?

Repairing damage to hollow composite decking depends largely on the type of damage.

For scratches which is common among all type of composite decking depending on the brand, you may be able to fix the damage with a heat gun. But do check with the manufacturer, many composite materials can not be repaired this way.

Others will recommend wax and/or colour markers to conceal the damage making it less noticeable.

Current hollow composite decking is less receptive to puncture damage. Where a heavy object breaks the shell of the decking.  Especially for cylinder composite decking which by design is stronger. Square cavities with weakened edges and corners are more prone to breaking. Hail in particular is its weakness.

For impact damage, there is little you can do to fix or repair the decking. Your best option is to replace the damaged board. 

Unfortunately, most hollow decking is not warranted against blunt force damage or structural damage caused by use. The fine print generally only includes structural damage caused by fungi. This does not include hail or falling steak knives.

Can you screw into hollow composite decking?

Most hollow composite decking can not be screwed into as there is not sufficient material to hold the screw. An alternative is installing hollow decking with clips or hidden fasteners designed for the decking groove. 

Can you screw down hollow composite decking?

Hollow decking cannot be screwed down onto the joists but can be installed using manufacture recommended clips to install the decking.

Hollow decking varies by the manufacturer of best installation method so always read installation instructions before installing.

Ryan Nickel

A Red Seal carpenter, passionate about building decks to be enjoyed.

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