How Far Apart Should Joists Be For Composite Decking
A lot of questions revolve around joists when it comes to building a deck.
How far apart should joists be for composite decking. Most deck joists are centered 16 inches apart which is the maximum deck joist spacing for most low maintenance decking. If you plan to install your decking at a 45 degree angle your joists may need to be 12 inches apart. Another mistake to avoid when installing composite decking is spacing the joists too far apart. Normally floor joists are spaced 16 inches apart on center.
With some structures floor joists are required to be 12 or 24 inches apart on center. The maximum joist spacing you can use will depend on the size and allowable span of your joists. Joist size spacing between joists decking material and wood species. Deck joist spacing should never exceed 16 on center with the exception of max deck boards which allow for maximum 24 on center.
How far apart are floor joists placed. Some brands like weardeck let you get away with more reinforced with a layer of fiberglass on both the top and bottom weardeck boards easily allow for spans of 24 inches oc. Deck joists are typically spaced either every 12 inches or 16 inches on center. For adjoining structures or posts remember to always allow for a 3 16 minimum gap where the decking meets the structure.
Two by twelve douglas fir joists spaced 12 inches apart on center for example can span 20 feet 7 inches but the same joists spaced 24 inches part can only span 14 feet 7 inches. Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist. For a more rigid feel 12 or less may be preferred. Most composite and pvc decking brands like trex and azek recommend a minimum joist spacing of 16 inches oc.
If you re planning to replace old wood decking with pvc or composite measure the deck joist spacing first. In general terms joists spaced 16 inches on center can span 1 5 times in feet their depth in inches. 3 joists are set too far apart. 2x10 to 15 feet and 2x12 to 18 feet.
This means from the center of one upright joist to the center of the next. The spans of joists varies based upon several factors. The chart below clarifies the appropriate deck board spacing based on the temperature at the time of installation. Current building codes require that all decks should be supported with a minimum of 2 x 10 pressure treated pine joists that are spaced 24 apart although 16 oc is standard building practice.
What is the proper placement. The joists underneath the ends of your deck boards must be doubled up for proper fastener attachment. For a more rigid feel 12 or less may be preferred. How far apart should deck joists be spaced.