A strong foundation is the first step to a well-built decking. To ensure a long-lasting composite deck, precise placing of the deck joist is crucial. If you want to install a deck in your outdoor space, you should place the joist accurately. This article will shed light on the joist spacing for composite decking s important. It will also discuss how far apart should you place your joist.

What Are Deck Floor Joists?

How Far Apart Should You Place Your Joists

Deck joists are horizontal beams that make up the frame that supports the deck. The joist is important to perfect the deck. It functions as a support for the deck, ensuring that the deck weight is evenly distributed. When building your deck, you have to place the deck joist correctly. You also need to ensure that the deck joist is properly paced.

Why Is Joist Spacing Important?

Joist spacing is very crucial in deck building. The spacing prevents your decking from sagging. If the decking joist is placed too far apart, it will cause the composite decking to sag. In addition, if the joist height is not equal to each other, it can also cause an uneven deck surface. To keep that from happening, appropriate spacing of the joist is important. It is important because the joist serves as a foundation for the deck. If the foundation is not installed properly, it will surely affect the deck. The decking space should not be too far apart, nor should it be too close. So, how far apart should you install your decking joist?

How Far Apart Should You Place Your Joists? 

Most composite decking manufacturers have guidelines on the length of joist spacing for their decking. When you purchase a decking, you will see a decking joist guideline. So, how far apart should you place the joist? Some manufacturers recommend a maximum joist spacing of 12 inches on centres, 14 inches on centre and 16 inches on centre. When installing the joist, you have to follow the manufacturer’s guidelines. There are various guidelines for placing joist for different decking sizes.

Additionally, joist spacing also depends on the angle and length of your deck. Some brands recommend 16 inches on the centre for 90 degrees angle. And also,14 inches on centre for 30 degrees angles and 12 inches for 45 degrees angles.

For residential decking, the joist space should not exceed 16 inches as measured on the centre. But if you want a more rigid feel for your decking, you can space the joist by 12 inches on the centre. Additionally, for commercial deckings, the standard joist spacing is 12 inches on the centre. Each region also has a building code for deck joist spacing. You should always check for the recommended joist building code. Knowing the appropriate joist spacing for composite decking, how can you install the joist properly?

Tips For Properly Installing Composite Decking Joist

First, when placing a joist for composite decking, you should ensure that the joist is levelled. You can do that by running a string line across the top of the joist often. If a joist part is too high than the rest, you should cut the part away. For a low part, you can add shims to make it levelled.

Secondly, you should ensure that the joist is structurally sound. You can do this by using blocking to support the joist. Blocking involves installing small pieces of wood between the joists. It increases rigidity, and it also prevents sagging or twisting of the joist.

 Lastly, you should cross-check your work. Check for protruding nails and screws. Taking your time to inspect the joist can add to the lifespan of your deck. So, always check your work and ensure the joists are properly place.


How far apart should you place your joist? Always follow the manufacturer’s guideline. Some manufacturers recommend a maximum joist spacing of 12 inches OC, 14 inches OC and 16 inches OC.