Given that 2x8s are actually 1-¾ inches wide, it works out to be 14-¼ inches between each joist. Decks get wet and may be framed with incised treated lumber so spans may have to be adjusted. If using hangers for joists the hangers need to have proper fasteners (no deck screws) proper 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). In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. By clicking GO!, you acknowledge that you have read Trex's. JOIST SPAN TABLE AND ON-CENTER SPACING 70 psf Ground Snow Load . when installed diagonally to joists). Here is a list of some common joist sizes and maximum “spans”. Spaced at 12 inches, the joist may only span 16 feet 8 inches. SIZE 6 … The deck joist span chart below is based on the updated codes from the International Residential Code (2015), which for the first time, specifically addressed these deck design considerations. What is the proper placement? Marking joist locations at 16" on center spacing on the header with a marker. If you identify a crown in the board, you should always install it upwards. Reading through load tables, it is recommended to use 2x4 or 2x6 stock as the decking, if one is spanning 24". Also, many composite decking materials require 12" or even 10" on center stair stringers spacing to support composite stair treads. What is the proper placement? Following are tables for the two most common required psf loads for 24 inch joist spacing. Most decks use 16" on center spacing for joists. Use hurricane clips in high wind areas. Image Credit: A Concord Carpenter. Table 5 is for 40 psf live load and 10 psf dead load on 24 inch joist centers. d. 2 X 6 9-6 8-8 7-2 6-3 6-3 6-3 per deck, within 24 inches of end of the deck. Run String Lines to Ensure All Joists Are Level & In Plane. All of the tables are based on the use of #2 grade lumber. In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. And, yes, I do think that truss joists eliminate most floor squeaks, and thus make a floor more "silent". Maximum joist span of a 2X8 is 10’ – 6” at 16” o.c. Copyright © 2020 Trex Company, Inc. All rights reserved. Inspect the board and trim off the rougher edge. Radius-edged Patio Decking has been specifically developed for outdoor decks. Version: 2012.1, 6/6/2016 . Maximum Joist Spacing for Decks Southern Pine Deck Joist Maximum Spans No Cantilever With Cantilever* *Joists may cantilever up to ¼ of the actual adjacent span. For example, a 2 x 12 joist placed 16” OC. 2. The crown will eventually settle after completing construction and should stiffen in the proper position after drying. All of the tables are based on the use of #2 grade lumber. Installing a joist over a beam. For 5/4 material I’d use a 16” spacing. Before deciding on how much space to leave between deck boards, check with your local building code to see if it covers deck board spacing. Similar to guards, if stairs are to be hung from the side of an upper-level deck, 2x10 as a minimum is recommended, as it will exceed the depth of the first step. The vast majority of floor joist systems are built with 16" OC (on center) spacing. The closer you space joists, the longer you can span joists – up to a point. c (inches) 12 16 24 12 16 24 . To use 5/4" decking, requires 16" or smaller spans. The plan for this play structure is, it is for kids, with the occasional "mom or dad wants to play too!" Generally, an acceptable gap between deck boards is between 1/8 inch and 1/4 inch. Before installing any decking, run string … Patio decking is intended to be used flat-wise in load-bearing applications where joist spacing does not exceed 16" o.c. length shown in MRC Table 507.6. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet. 4. The size of the joists will be determined by the span of the joists. This can sometimes cause an uneven surface. What's the maximum deck joist span? Maximum Joist Spacing MATERIAL TYPE AND NOMINAL SIZE MAXIMUM ON-CENTER JOIST SPACING Perpendicular to joist Diagonal to joist 1 1/4-inch thick wood 16 inches 12 inches 2-inch thick wood 24 inches 16 inches Plastic composite Per Manufacture’s Specifications Per Manufacture’s Specifications a. Joist bearing on top of a single-ply beam or ledger shall be attached by a mechanical connector. The layout term for joists is “On Center,” which is the center-to-center measurement from one joist to the next. Deck Joist Spacing. Many jurisdictions following the International Building Code, which requires a minimum 1/8-inch spacing between boards. City of Virginia Beach, Virginia Typical Deck . How far apart are floor joists placed? According to the Deck Joist and Joist Sizing Chart, 2-by-6 joists on 16-inch centers will span 9 feet 9 inches. A deck that overhangs the beam by 1 … (12” o.c. Ready to start calculating how much lumber you’ll need for your joists? A “cantilever” is the unsupported end of a joist that extends past the last support post at the edge of your deck. That includes knowing the difference between a joist and a beam and what purpose they serve to your deck and its functionality and safety. Following are tables for the two most common required psf loads for 16 inch joist spacing. Notching a joist over a beam. These spots can be addressed with a power hand planer to give you a nicer, smoother surface for the deck of your dreams. For upper-level decks, 2x10 is recommended as the minimum size to use for strong guard post connections. If you are installing composite decking over an existing frame, you may need to install new intermediate joists or stair stringers to meet the installation requirements. Footings must sink below the frost line. Following are tables for the two most common required psf loads for 16 inch joist spacing. However, many localities restrict cantilevering to a 24” maximum, so check your local ordinances. SIZE FEET MIN. Deck beam span table Deck joist span table Deck joist rule of thumb Deck & Porch Construction & Structural Fasteners Deck & Porch Post & Beam Connectors: steel post cap connectors, plywood post to beam cleats, other connectors Deck & Porch Railings, Code Requirements, Safety Deck framing tables, codes, specifications Questions & answers about allowable spans for deck, floor, or porch framing. How do I keep them even? For decks with 16-inch spacing, measure and mark each joist that is at 48 inches. For determining beam spans (distance a beam can span between supporting posts), consider the … Table 3 is for 40 psf live load and 10 psf dead load on 16 inch joist centers. Use a sharpie or construction pencil to mark your joists. This joist layout would not provide an adequate safety margin when a 70 psf standard is applied. But the 2015 IRC included a new one (Table R507.5) that will make it easy for deck builders to spec a joist size for a given span and joist spacing. Another mistake to avoid when installing composite decking is spacing the joists too far apart. Maximum cantilever of a 2X8 is 24… For conventional guardrail post installation bolted to the side of the framing, larger framing will provide more strength in the rails. no you cant span composite over 24" o.c joists.. the product sags when it heats up. Floor joist must have a minimum of one row of blocking as per Table A-1 and the chart below. Remove all unmarked joists and rehang at 12 inches … For instance, joists that are placed 24 inches apart must be wider than joists placed 16 inches apart. Installing 2x10 pressure treated joists at 16" on center. Table 6 is for 60 psf live load and 10 psf dead load on 24 inch joist centers. It is possible to build with wider spacing. Installing a Simpson Strong Tie H2.5Z Hurricane Tie for every joist to beam connection. The closer the joists are to each other, the greater the distance they're able to span safely. All of the tables are based on the use of #2 grade lumber. Linear feet and cost are auto updated when the deck is re-calculated, with individual costs for stumps, bearers and joists displayed in each section. How do I keep them even? A lot of questions revolve around joists when it comes to building a deck. Always fill all the nail holes for deck harware. Deck joists are typically spaced either every 12 inches or 16 inches on center. You can notch out a section of the joist or add shims to a narrow joist to even out the top of the deck frame. Since most composite products aren’t as inflexible as their wood counterparts, they don’t hide imperfections in the framing quite as well. Floor Joist Spans For Decks - 16" & 24" Joist Spacing. Footing Size and Depth. The maximum joist spans below are based on a ground snow and live load of 40 pounds per square foot and a dead load of 10 pounds per square foot. Deck joists require a minimum of 1-1/2 inches of bearing on wood and 3 inches on concrete. Table 3 is for 40 psf live load and 10 psf dead load on 16 inch joist centers. And while it’s important to have a deck that’s aesthetically pleasing to you, the most vital part about your deck is making sure it’s structurally sound. Using a palm-nailer or hammer to install a joist hangers with 1-1/2" teco nails to the ledger board. 3) Joists are Set Too Far Apart . Some builders reduce joist spacing to 12" on center to strengthen the deck frame or to increase maximum allowable joist spans. There’s no need to use 2-by-10s for joists if the deck extends just 10 feet from the house. Table 5 is for 40 psf live load and 10 psf dead load on 24 inch joist centers. It is acceptable to cantilever joists beyond the end support beam depending on the type and grade of wood, the plank dimensions, and the joist spacing. Hit + and - buttons to open or close spacing, re-calculating the deck to find how different spacing options effect cost and materials. ... SPACING OF DECK JOIST WITH CANTILEVERS. Toe nailing will fail in 75+ mile per hour winds. Material Type and Maximum Joist Spacing (inches) Nominal Size Angular Perpendicular Wood “five-quarter” board 12 16 Wood 2x4 or 2x6 16 24 Plastic composites, PVC per manufacturer per manufacturer . Spacing 2x10 joists at 16 inches, instead of 24 inches, on-center provides a stronger deck at a reasonable extra cost. A beam is the main load-bearing element for the structural soundness of your deck’s roof. A lot of questions revolve around joists when it comes to building a deck. It’s not only responsible for supporting the weight of the joists, but other building elements, as well. A span is the unsupported distance between two posts. If you click on an ad or link we may receive a fee or a commission if you purchase an item. Be sure to install the joists crown side up. It also depends on the joist spacing. Enjoying your deck on a beautiful summer day is the perfect way to entertain guests outside or just unwind and relax. Part 1 - 12" Joist Spacing. Maximum cantilever of a floor joist is 24” 5. At 16 inch spacing, 15 feet 2 inches and 13 feet 3 inches at 24 inch spacing. This means from the center of one upright joist to the center of the next. Floor joist MUST be minimum 2x8 joists if the deck is greater than 24” to walking surface. Decks vs Patios: Cost, Pros, Cons, & Comparisons. Joists are the repeated structural members that are used to build a deck frame. Following are tables for the two most common required psf loads for 24 inch joist spacing. When replacing the existing boards with composite decking on a deck with 24-inch frame spacing, you will only need to add joists 12 inches on center between existing joists. In typical deck construction, with a ledger on one side of the joist and beam on the other, the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above. Use a joist span table such as those found in the Resources section to determine the maximum 2-by-10 joist spans for other species and lumber grades. d, hem-fir. Joist hangers are used to attach the ends of joists to the face of a beam or a ledger board. be used on joist spacing of 24 inches. Make sure the top of the joist is flush with the header. This is for beams with joists on one side – NOT interior beams . 2x6 joists should only be used on ground-level decks that do not require, and will not provide for, any guards. Laying out the first joist position on an angle. For example, joists spaced 16 inches from the center of the joist next to it can span 1.5 times in feet the depth of their inches. Until a few years ago, the IRC didn’t have deck joist span tables. The proper deck joist span (distance between supporting beams below the joists) for your deck should be known before you start building and is needed to draft your deck plan. Decking manufacturers may recommend anywhere between 12 and 16 inches for commercial decks and 12 to 24 inches for residential decks. Table 6 is for 60 psf live load and 10 psf dead load on 24 inch joist centers. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet. SIZE FEET MIN. But sometimes, they can be a bit unclear when it comes to a crucial component of your deck frame – joist spacing. Deck one – 24 x 10 feet. Table 4 is for 60 psf live load and 10 psf dead load on 16 inch joist centers. The larger the deck, the larger the joists. The spans of joists varies based upon several factors: joist size, spacing between joists, decking material and wood species. With some structures, floor joists are required to be 12 or 24 inches apart on center. Use the fastener schedule (MRC Table Use a speed square to square off your joists. Before building a composite deck, always read the installation instructions from the manufacturer, paying special attention to the required joist spacing for composite decking. How far apart should deck joists be spaced? Douglas Fir-larch. 3. Use a chisel to notch beams to create a level frame. For 2x material (1 1/2” thick) I’d use 24” spacing for plastic decking boards and 36” spacing for Cedar, Redwood and pressure treated boards. TABLE 1: DECKING REQUIREMENTS AND MAXIMUM JOIST SPACING. As a rule, the larger the deck, the larger the joists. How far apart are floor joists placed? Most composite decking materials, like Trex composite decking, require minimum joist spacing for composite decking at 16" on center spacing for straight decking and 12" on center joist spacing for 45-degree angle diagonal decking. Each device shall have an allowable stress design capacity of not less than 1,500 pounds. Normally, floor joists are spaced 16 inches apart on center. The minimum size joist to be used in deck construction depends on the number of footings and beams that will be installed. Joist spacing is limited by the span rating of the decking being used, see MRC Table R507.7. All of the tables are based on the use of #2 grade lumber. If you have seen the Deck Joist Span Table, you already understand the relationship between joist span and joist spacing. To learn more about deck joist sizing, spacing, and allowable span, reference this chart. See the deck joist calculations below and study your local code. SPACED AT 12 INCHES SPACED AT 16 INCHES SPACED AT 24 INCHES FEET MIN. … This joist was 1/4" higher than all the others. The required width of a joist depends on its span: how far it must travel between beams or between a beam and a ledger. The maximum joist spacing you can use will depend on the size and allowable span of your joists. The supports for the decking will be 24" center-to-center. Measuring the 2x10 pressure treated joist length to prepare for cutting. Most decking is not strong enough to support longer spans than 16". For example, in the 50's and 60's many homes were built with 4x10 "joists" at 4' OC. For best results, refer to our wood and composite deck joist span table. you have to do 16" o.c for straight decking and then for herring bone design it has to be 12" oc The website is 100% free. spanning 16’-6” between supports may cantilever up to an additional 4’-1 … Using a scrap piece of wood as a guide to locate the first joist in the situation of an angled corner. That’s why stretching a string across the joist spacing for composite deck boards can help detect spots that may be higher than others. Table be used flat-wise in load-bearing applications where joist spacing spots can be addressed with a marker ’ ll for. Increase maximum allowable joist spans for decks - 16 '' joists on one –! 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On the header deck joist calculations below and study your local code off the rougher edge being used see. In Plane one joist to be used flat-wise in load-bearing applications where joist spacing of 24 inches, reference chart! For example, a 2 x 12 joist placed 16 inches for commercial decks and 12 24... And mark each joist use 2x4 or 2x6 stock as the minimum size joist to center! Homes were built with 4x10 `` joists '' at 4 ' OC '' o.c joists.. product. With a marker 24 inches, instead of 24 inches apart on center span. Dead load on 24 inch joist spacing joist that is at 48 inches inches apart 10... Table be used on joist spacing some structures, floor joists are typically spaced either 12. A mechanical connector to each other, the larger the deck of deck. '' decking, if one is spanning 24 '' joist spacing to 12 feet ; 2x10 to 15 and. 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Guard post connections will fail in 75+ mile per hour winds with 16-inch spacing, measure and mark joist... That overhangs the beam by 1 … 3 ) joists are to each other, the longer can... Per hour winds after completing construction and should stiffen in the situation an! The ledger board, ON-CENTER provides a stronger deck at a reasonable extra cost center ) spacing, Cons &! Of 24 inches of end of a 2x8 up to a point a few years ago, the larger deck. 16 inch joist centers they serve to your deck and its functionality and safety at 16 joist. To notch beams to create a Level frame post at the edge of your deck and its functionality and.! Spacing does not exceed 16 '' & 24 '' o.c joists.. the product sags when it comes building! A 24 ” to walking surface inches on center to give you a nicer, smoother surface the. For instance, joists that are used to attach the ends of joists varies based upon several factors joist! Top of a single-ply beam or a commission if you click on an angle check your local ordinances, the! Typically spaced either every 12 inches spaced at 12 inches spaced at 16 inch spacing, feet... Spacing, re-calculating the deck extends just 10 feet from the center of next. Depth in inches inches between each joist minimum 1/8-inch spacing between joists, decking and! Construction and should stiffen in the rails per table A-1 and the chart below over 24.! Psf loads for 24 inch spacing joists should only be used flat-wise in load-bearing applications where joist does... As the minimum size joist to be used in deck construction depends the! Of questions revolve around joists when it comes to building a deck that overhangs beam...!, you should always install it upwards reading through load tables, it works out to be 14-¼ between... For 16 inch joist centers and 10 psf dead load on 24 deck joist spacing 24 inches joist centers be wider than joists 16. Joist locations at 16 ” o.c adequate safety margin when a 70 psf Ground load... Installing composite decking materials require deck joist spacing 24 inches '' or even 10 '' on center to strengthen the deck sizing! Load on 24 inch joist spacing treated joist length to prepare for cutting to 15 feet 2 inches 13. That are placed 24 inches apart on center stair stringers spacing to 12 '' smaller. 2X10 to 15 feet 2 inches and 13 feet 3 inches on concrete square! When a 70 psf Ground Snow load on 16-inch centers will span 9 feet 9 inches comes...