However, if your deck will include a hot tub or roof, you must support that weight with additional footings. Drop beams are also stronger than flush beams because they rely on the wood structure to support the weight rather than metal fasteners. He is passionately interested in home improvement, renovation and woodworking. This means for a 12-foot span, you can cantilever up to three feet beyond the beam. In the example below, the post spacing is changed from 96" to 48". It’s essential to comply with the building code to ensure proper deck post, footing, and beam spacing. The smaller the spacing, the longer your joists can span. So, rather than using a 6×6 beam, this would mean using three 2x6s bolted together. She would like it to be as high as possible, with. A flush beam is positioned at the same level as the joists. The Joist span table below is for joists with a continuous span on a deck below 1metre in height. This distance is half the distance to the next beam in either direction. For Beam 1, use a joist length of 13’, (6’+7’) and a post spacing of 9’. A deck beam is a board or collection of boards that support the deck joists and decking. There are two types of deck beams to consider: flush beams and drop beams. distance that a given size of beam can span before another post is Changing joist span, depth, and spacing has a dramatic effect on deck strength. 4x6 beam should span no more than 6' between supporting posts. Beam Deck Post Post Cap 2 ½â€ min. Deck Joist Spacing & Blocking Tips Step 1: Check That Your Deck Frame Is Structurally Sound. Cut a 3-inch-wide notch in the post to match the width of the beam. you already understand the relationship between joist span and joist The tributary area, coupled with the live load or snow load for the locale, and the soil’s load bearing value are used to identify the required dimensions of the footing (Reference Table R507.3.1 of the 2018 IRC).. Several sites offer deck framing calculators to help you make these determinations. Refer to the Deck Beam Span Table below to assist in determining the maximum span of a given beam between posts. First, the IRC only allows certain dimensional lumber to be used for deck beams. A 3 ply 2×10 beam can handle a span of 8 feet 6 inches for a joist spanning 14 feet and 7 feet 11 inches at 16 feet. Joist Span – Joists Attached at House and to Side of Beam. The closer you space joists, the longer you can span joists – Cantilevering the beams allows the posts to be partially concealed beneath the deck, creating a more visually appealing look. Beams rest on and secure to Code compliant and spaced deck posts and footings for support. The maximum distance between footings is … the longer the supported length of joist that a beam must carry, the Remember, the IRC allows you to cantilever joists up to one-fourth of the joist’s span from beam to beam (or in this case, from ledger board to beam). Dimensional Lumber Joist Size and Spacing Flush beams are typically used for small decks or those with unconventional shapes where drop or cantilever beams won’t work. According to IRC, a two-ply 2×10 beam supporting a joist that spans 8 feet between supports requires beam support posts every 9-feet. Determine the length of the joist actually supported by the beam. Privacy Screens -How High Can I Go With Titan Wood Post Anchor? The Joist Span indicates that 2x6s at 24” O.C. The narrower the spacing between joists, the greater the span can be. With a flush beam, the joists are attached to the beam using joist hangers. You’re planning that amazing deck you’ve always dreamed of, but you’re not sure how the framing should work. A Redwood 4x6 beam should span no more than 6' between supporting posts. Joist direction, size and spacing Location of posts and deck blocks supporting beam Spans between beam support posts Beam cantilever distance (if applicable) Dimensions of the deck Area of the deck Stair location (if applicable) The location of the house relative to the new deck Stair dimensions Larger decks commonly require additional deck beams in the middle to provide support. Remember, you need enough beams to keep the span of the joists in code. Span entries are listed for 2×6 through 2×12 joists and 12 in., 16 in., and 24 in. This is where cantilevering can save you time and money. Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. It can save you materials by allowing you to extend your deck several feet further without adding additional posts. © 2004-2019 Decksgo.com. All Rights Reserved. Composite decking brands also generally require 12 inches O.C.joist spacing for 45-degree or angled composite deck board applications. spacing. 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. You can use two beams, one at 7.5 feet and one at 15 feet, to provide support. If you’re building a longer deck, you won’t be able to use a single piece of dimensional lumber to create the length of your beam. The greater the joist span, the less distance the beam can span. The span of the joists the beam is supporting also determines the maximum deck beam span between support posts. Starting about 2 inches from the edges of the beam, counterbore two holes on the inside (or the least-visible side) of the beam for carriage bolt nuts. The standard rule for footings is that for a basic deck, the larger the beam and footing size, the fewer footings you'll need. Keep in mind that some species are only available in certain parts of the country. Working in concert with the deck posts and footings, a deck beam is responsible for holding up the joists, which holds up the decking. Why use a cantilever? Having the right number of deck beams is essential to building a safe and sturdy deck. While this can vary depending on the size, species, and grade of the framing lumber, a deck with 2×8 southern pine joists spaced 16 inches apart must be supported by a beam a maximum of every 12 feet. A two-ply 2×10 beam, for example, has an allowable span of just 6 feet 9 inches for a joist spanning 14 feet and 6 feet 4 inches on 16 feet. As such, proper deck beam spacing is crucial for a structurally stable deck. Offset From End. The majority of composite deck board brands including Trex, TimberTech, and more require deck joists spacing to be at 16 inches O.C. The end of each beam shall have a minimum of 1 ½â€ of bearing on wood or metal or 3“on masonry located at interior posts Joist Beam Ledger Board 2 rows 10d (3” X.128”) nails or wood screws placed 16” O along edge of both sides of beam (2) ½â€ diameter through-bolts with washers under head and nut 5 ½â€ min. Extending the deck past the posts softens the look of a deck by hiding the posts. Most decking is not strong enough to support longer spans than 16". With this in mind, the depth of the joist determines the spacing of the beams. This, of course, would mean the additional cost of a second beam, support posts and footings along with the labor of digging the footings and installing the posts. (on center) for standard straight composite decking installation. If you have internal beams, stagger the splices on each so they aren’t lined up on the deck. If you are still unsure what the deck beam requirements are for your deck design, feel free to reach out using the comment box below. The beams are (3x)2x6x16 glued and screwed together. To provide support for the joists, deck beams must span the entire length of the deck. The joists will then extend over the beam in a cantilever position. 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. Lightweight steel beams are becoming more popular due to their durability and precision. A drop beam is positioned under the joists to bear the weight of the frame. A 2×6 joist can span up to 9 feet, a 2×8 can span up to 12 feet, and a 2×10 can span up to 15 feet. At Softwoods we use 450mm spacing as a default as it provides ample support in almost all uses. Deck joist spacing is the distance between joists, measured from the center of one joist to the center of the next, and is commonly 12, 16, or 24-inches. Most dimensional lumber maxes out at 20 feet. determines the force that bears upon that beam and therefore the Although we used International Residential Building Code requirements to make our calculations in this article, it’s important to check your local building codes to see if your municipality’s requirements are more stringent. First, plan where the splice will be located on the beam. In that case, the required spacing of the posts will be based on the deck loading, the span of the beams, and the geometry of the deck. Secure the beams to the post using four carriage bolts. Plan in advance by knowing the correct deck beam span to use. The International Residential Building Code requires that you have enough deck beams to support the deck’s joists adequately. Example: a = 12'; Post spacing # 8' Use the joist span table to find the acceptable joist sizes for a 12' span, 2x8s at 12" O.C., 2x10s at 16" O.C., or 2x12s at 24" O.C. When the deck joists are 8 ft. long, the beam can span 7-7. beams. In general, posts should be spaced no more than 8 feet apart. Most span tables use Southern pine for their calculations, but this isn’t the only material you can use for a beam. Install the two beams so the ends butt together and rest on the notch. According to IRC, a two-ply 2×10 beam supporting a joist that spans 8 feet between supports requires beam support posts every 9-feet. While cantilevering can add width to your deck and eliminate the need for additional footings, posts and beams, sometimes it isn’t enough. The drop beam design has two advantages. For a deck that is 15 feet wide with 2×10 joists spaced at 16 inches apart, you have two options. beams or a beam and a ledger, each beam (or ledger) supports half of the To determine the correct joist required, we need to establish the spacing of our joists. Then divide this measurement by the maximum floor joist spacing that is mentioned on your drawings. But let’s first explain what the numbers in the chart actually mean, because it can be a bit confusing. The Beam Table indicates that the beam may be two 2x10s or two 2x12s, depending on the wood used. Beam Spacing. Deck Post Spacing. use. Joists may bear on the beam and extend past the beam face up to the lesser of L O Some builders reduce joist spacing to 12" on center to strengthen the deck frame or to increase maximum allowable joist spans. Since cantilevering places more stress on the beam, it can only be used with drop beam styles of framing. When supporting joists that span 12 feet with no overhang beyond the beam, a double ply beam can span in feet a value equal to its depth in inches. on-center spacing. The limitations of how far a joist can span determines just how many beams you’ll need. For example, to cover a 30-foot space, you might use two 2x8x10s and two 2x8x20s. Figure 2. Lumber Species Southern Pine Douglas Fir Douglas Fir-Larch Hemlock-Fir Spruce-Pine-Fir Redwood Western Cedar Ponderosa Pine Red Pine The span of the joists the beam is supporting also determines the maximum deck beam span between support posts. 2" thick deck boards should be spaced approximately 1/8"; most builders set a 16d nail between the boards as they fasten them. Fasten the deck boards at each joist. Lumber Species Southern Pine Douglas Fir Douglas Fir-Larch Hemlock-Fir Spruce-Pine-Fir Redwood Western Cedar Ponderosa Pine Red Pine It also depends on the joist spacing. BEAM SIZE & ASSEMBLY REQUIREMENTS Deck beam spans shall be in accordance with Table 3 and can extend past the post face up to L B /4 as shown in Figure 3. For determining beam spans (distance a beam can span between Refer to the Deck Beam Span Table below to assist in determining This table compares requirements at both minimum (50 psf) and elevated (70 psf) design loads. I am looking to install privacy screens on my concrete patio. Dig the footing and install posts for each area of the splice, planning the length of each side of the splice. joist. Or, you can make life easier for yourself and cantilever the joists up to three feet six inches beyond the beam to reach 15 feet, keeping the deck frame in code and eliminating the need for an internal beam. by Julien (Quebec, Canada) I'm building a 16x16 deck and I'm searching for how many beams and what spacing do I need to have between each beam. Starting with your perimeter, mark the location of each deck post to locate the fitting position. My plan was to pour concrete footings, then run doubled up 2x8 beams setting on the footings, My wife is a stroke victim, and she wants this deck to be as easy as possible for her to walk out on. Determining proper deck beam spacing can be confusing. According to the 2018 International Residential Code, beams can cantilever at each end up to 1/4 of the actual beam span (R507.5). Cost estimates and framing layouts are provided for comparison only; actual costs will vary for different markets. The IRC also regulates how far a deck beam can span before it needs support from a post and footing. Joist Spacing & Span. When calculating beam span, the general rule of thumb is pretty straightforward: the longer a beam spans, the bigger it needs to be to support that span. A deck with 2×8 joists spaced 16 inches apart will need to be supported at least every 12 feet to provide adequate support for the joists and comply with building codes. Use this to specify the spacing between the posts that support the deck. If the outside edge of your deck is at least 17” above grade, a double 2x8 beam should be installed to support the joists along the outside. Some builders position them every 4 feet for a completely rigid frame. Joist Span – Non-Ledger Deck. Remember to complete all calculations using millimetres. I just want to put up two 6x6 posts with Titan Wood Post Anchors, either 35 or 70 apart, I am building a 10'x12'deck (not attached to a ledger board). Refer to Table R507.5 of the 2018 IRC for specifics. To properly space deck beams, you need to consider the joist span. A double 2x12 beam can span 12 feet; a (2) 2x10 can span 10 feet and so on. Joist Span Calculator For help, simply click on the beside the section you need help with, Or watch this Tutorial Video. Smaller decks typically rely on a single beam that runs along the deck’s outer edge, providing support for the joists in conjunction with the ledger board attached to the house. The last board won’t look good if it’s skinny or cut at an angle. Whereas a 10 feet can span up to 6 feet 6 inches. Check with your local code official, or simply drop back to the shorter value in the table and assume the allowable span is 7-7. Beam Span Calculator For help, simply click on the beside the section you need help with, watch this Tutorial Video. Decks use 16 '' on center spacing for the tributary area this would mean using three 2x6s bolted to... Hope this article answered all of your deck also affects the maximum span of given. Decks or those with unconventional shapes where drop or cantilever beams won’t work ) standard... 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