How Close Should Joist be For Composite Decking?


Composite decking is the leading choice for homeowners. Composite materials are durable and beautiful decking options made from recycled plastic and reclaimed wood. Not only is it reliable, but it’s eco-friendly as well. Aside from that, it’s also cheaper than regular decking when compared in the long term.

Another great thing about composite decking is the ease of installation. You don’t need to cut, treat, or sand the materials. Instead, you can immediately start working with them. In some cases, you can also have the materials measured and customized. But one of the best conveniences of using composite materials is that they don’t require any complicated foundation. You don’t have to lay a solid foundation, or set up concrete, for your composite decking. Instead, you will only need a basic joist frame to act as the foundation.

But here’s what confusing for many people; how close should joist be when using composite materials? For most manufacturers and suppliers, a guide or instruction will come with the composites. In most cases, decking suppliers often recommend 8-16 inches for decks for commercial use, whereas for residential decking, the standard spacing is anywhere from 10 to 16 inches.

To understand better, let’s answer one crucial question. Why is joist spacing so important? How can the spacing affect the overall outcome of your decking construction?

Why Decking Joist Spacing Measurement Important?

For people not familiar with decking foundations, joists are a series of horizontal support beams of a frame, transferring the weight to the vertical bars of the frame. The more close each individual joist is, the more sturdy the floor becomes. On the other hand, if they are too far from each other, the result will be a sagging floor. If the joists are not aligned, it will result in an uneven floor.

Now, considering that closer joists mean sturdier floors, does it automatically mean you have to narrow down the gaps between them? Not necessarily. If you put them too close to each other, it’ll be too difficult for you to do the installation. Certain areas will be very hard to reach.

how close should composite decking joists be

How to Properly Set Up Decking Joist Spacing

So the question is, how big of space should you set your joists apart when you are doing decking installation? And what can you do to install them properly? Here are some of the things that you should always remember.

  • Be familiar with “On Centre” measurement. Before anything else, you should know what On centre means, often abbreviated as OC. It is the distance between the centres of two joists. It is the standard measurement when it comes to measuring joist spacing.
  • Always follow the guidelines. For most composite decking suppliers, instructions regarding joist spacing often come with the materials. It means that you don’t have to decide for yourself. Instead, follow the guidelines and instructions supplied by the manufacturers. Aside from the supplier’s instructions, make sure to adhere to the building code where you’re living. In some places, there is a minimum spacing required by the building inspectors, especially if it’s for commercial use.
  • When unsure, consider the minimum joist spacing for each composite decking material. There are times that you have to decide for yourself how far apart the joists will be. In these cases, it’s essential to be familiar with the minimum spacing distance provided by the makers. For instance, some brands the minimum spacing is 10-12 inches for residential, while you can get away with 12 inches for the others.
  • Know the purpose of the deck. For commercial use, the usual joist spacing standard is 8 inches, due to safety precautions. As for residential use, you don’t necessarily need 10 inches, unless you are building a 45-degree angle deck. In this case, most suppliers recommend 10 inches for joist spacing.
  • Correctly install the joists. Your joists are crucial to the outcome of your decking project. Aside from joists spacing, you want to level your joists as precisely as you can. Make sure that there are no protruding screws and nails. If necessary, you can set small pieces of decking materials in between the joists to make them more stable.
Tags: decking anchors, decking Joist, decking joists spacing, Joist

Leave a Comment

Shopping Cart