joist spacing for composite decking cameron posted in general discussion on august 3, 2004 04:11am i am getting ready to add 2 new decks to my house using some sort of composite decking.
ilevel trus joist tji joist specifiers guide tj-4000 february 2008 all in one 2 design properties 3 material weights 3 floor span tables 4 floor load tables 5 psf to plf conversion table 5 floor performance 6 tj-pro rated floor system 7 silent floor joist framing 8 floor details 9 fastener spacing and diaphragm design 9
i just tore off the old decking from my cabin's deck. the joists are set 24' on center as opposed to the 16' on center that were in the specs. should i take all the joists out and replace all of them, or add a new joist between each existing joist? the deck is about 12 years old and some of the joists have to be replaced due to rot.
determining the correct deck joist spacing and span is actually more complicated than you may think. although building a deck seems strhtforward, there are a few important design factors to keep in mind. your maximum joist span will depend on the wood species, joist spacing, size and whether the joists will be cantilevered.
when using surface fasteners to secure railing to a composite deck, joist location may affect the ease, price and method of the installation of the railing system. leaving the required 1.5 spacing for surface fastening at the end of the board and 1 from the side of the board, requires two joists for every end-to-end seam.
here is a deck poorly installed with no deck spacing, and no ventilation. i'm sure the deck joists and structure have suffered from this installation. those steps look a bit slippery too. these deck boards are seven trust or another synthetic decking material.
if not, does anyone make a composite rated at 24' joist spacing? warning: the topics covered on this site include activities in which there exists the potential for serious injury or death . contractortalk.com does not guarantee the accuracy or completeness of any information contained on this site.
when building a house or even a deck, it is important to confirm you have the correct joist sizes, spans and spacing before you get started. while most residential construction uses 2x8 joists with 16 inch spacing, there are many other factors you need to consider when determining the proper joist span length.
for 5/4 material id use a 16 spacing. for 2x material 1 1/2 thick id use 24 spacing for plastic decking boards and 36 spacing for cedar, redwood and pressure treated boards. the size of the joists will be determined by the span of the joists. wed need more info to determine that
spacing the same 2x10 joists 16 inches on-center produces a much stronger deck the safety margin increases to about 79% beyond the minimum requirement , but at what cost? this spacing requires four more joists, or about 44% 4/9 more material; at $16 each for the extra joists and hangers, the added cost is about $72 depending on prices in your location for material only.
so, what is the proper shed floor joist spacing? spacing joists in your shed 16-inches on center will give you a firmer feel with less bounce and increase the load capacity of the floor. while you may be ok with the joist span at 24 inches the floor will be maxed out to the limits.
in other words, they deflect more when loaded. this may mean that the floor joist spacing may have to be adjusted closer spacing so that the flooring doesn't feel spongy. be sure to look for these recommendations in the literature before you buy. adding floor joists will cost you more money.