Secure the beams to the post using four carriage bolts. The Beam Table indicates that the beam may be two 2x10s or two 2x12s, depending on the wood used. To determine the correct joist required, we need to establish the spacing of our joists. The length of joist span actually supported by a beam is what When building a deck with 7-ft. joists, you know the beam can span somewhere between 7-7 and 8-0, but you don’t know exactly where. 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. © 2004-2019 Decksgo.com. Beams are made out of a variety of treated dimensional lumber. Offset From End. you already understand the relationship between joist span and joist 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. Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. A double-ply beam can span in feet the number of inches it is deep For example, a double 2×12 beam can span up to 12 feet while a double 2×10 can span up to 10 feet. The weight load of your deck also affects the spacing of the posts. beams or a beam and a ledger, each beam (or ledger) supports half of 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. You can use two beams, one at 7.5 feet and one at 15 feet, to provide support. use. Refer to Table R507.5 of the 2018 IRC for specifics. 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. The IRC also regulates how far a deck beam can span before it needs support from a post and footing. Maximum 2x6 Deck Joist Span She would like it to be as high as possible, with. Lumber Species Southern Pine Douglas Fir Douglas Fir-Larch Hemlock-Fir Spruce-Pine-Fir Redwood Western Cedar Ponderosa Pine Red Pine Joist Span Calculator For help, simply click on the beside the section you need help with, Or watch this Tutorial Video. Most decking is not strong enough to support longer spans than 16". The formula looks like this: (Overall length of deck – Floor joist thickness) “Maximum floor joist spacing/centre” Now your final answer is almost never a round number. Once you understand the limitations of the joist span on your deck, you can determine how many beams you need. It makes sense if you think about it. For a deck that is 15 feet wide with 2×10 joists spaced at 16 inches apart, you have two options. Red pine, fir, hemlock, cedar, redwood, and SPF (spruce-pine-fir) are just a few species that also function as beams. shorter the span of the beam – for a particular size of beam. 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. the joist plus any cantilevered portion of the joist past the beam. For the calculations in this article, we will use treated southern pine, which is the most common wood for beams and offers the greatest span of any wood type. 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). A Redwood Composite decking brands also generally require 12 inches O.C.joist spacing for 45-degree or angled composite deck board applications. Remember to complete all calculations using millimetres. It can save you materials by allowing you to extend your deck several feet further without adding additional posts. Deck beams serve an integral role in the framing of your deck. 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. 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. A steel beam can hold remarkably more than a wood beam, which reduces the number of support posts needed. Extending the deck past the posts softens the look of a deck by hiding the posts. Joist Spacing for Composite Decking the midway point between the supported ends (either a ledger or beam) of So, rather than using a 6×6 beam, this would mean using three 2x6s bolted together. your planning stage, don’t forget to consider the spacing for your The beams are (3x)2x6x16 glued and screwed together. Span entries are listed for 2×6 through 2×12 joists and 12 in., 16 in., and 24 in. Below are some common beam span values from Table R507.5 of the 2018 IRC: A cantilevered beam extends beyond the end post or posts. There are two types of deck beams to consider: flush beams and drop beams. The drop beam design has two advantages. Privacy Screens -How High Can I Go With Titan Wood Post Anchor? Cut a 3-inch-wide notch in the post to match the width of the beam. The thickness of the beam determines how far a beam can span between support posts. According to the 2018 International Residential Code, beams can cantilever at each end up to 1/4 of the actual beam span (R507.5). Home > Building A … Decking Beam Span Guidance We recommend beams are constructed from two 44 x 145mm Q-Deck deck joists and are placed at maximum centres of 1.8m. 5/4 x 6 pressure-treated decking may be placed with each board flush against the next; natural shrinkage will provide the proper spacing. Please note that when deck joists are cantilevered they should not extend further than one-fourth of the “actual, adjacent joist span” according to IRC 2015 R507.5. The distance you choose affects the maximum span, or how long your joists can be without compromising the strength of the deck frame. Use the Beam and footing sizes table and find the 8' post spacing column. 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. 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. Most span tables use Southern pine for their calculations, but this isn’t the only material you can use for a beam. This will ensure a stronger frame. With this in mind, the depth of the joist determines the spacing of the beams. With a flush beam, the joists are attached to the beam using joist hangers. the maximum span of a given beam between posts. If a joist spans between two The majority of composite deck board brands including Trex, TimberTech, and more require deck joists spacing to be at 16 inches O.C. This translates into fewer holes to dig and materials to purchase. Larger decks commonly require additional deck beams in the middle to provide support. joist. In this instance the maximum span between deck post centres is 2.07m (C16) or 2.24m (C24). Deck beams typically run perpendicularly to the joists and may run parallel or perpendicular to a structure. Total height of low level ground level deck. The ends of each joist, beam or girder shall have at least 1 ½" of bearing on wood or metal except where supported on a 1"x4" ribbon strip nailed to adjacent studs. The standard rule for footings is that for a basic deck, the larger the beam and footing size, the fewer footings you'll need. The International Residential Building Code (IRC) has strict requirements for deck beams and deck beam spacing. To properly space deck beams, you need to consider the joist span. What if your deck is more than 20 feet long? the longer the supported length of joist that a beam must carry, the Use this to specify the distance the deck posts are offset from the end of the beam. Cantilevering the beams allows the posts to be partially concealed beneath the deck, creating a more visually appealing look. The greater the joist span, the less distance the beam can span. The International Residential Building Code requires that you have enough deck beams to support the deck’s joists adequately. This table compares requirements at both minimum (50 psf) and elevated (70 psf) design loads. Use this to specify the spacing between the posts that support the deck. In the example below, the offset is changed from 12" to 24". 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. You must use 2x material bolted together to create a deck beam, or use metal or engineered lumber. However, if your deck will include a hot tub or roof, you must support that weight with additional footings. Obviously, the larger The Joist Span indicates that 2x6s at 24” O.C. To provide support for the joists, deck beams must span the entire length of the deck. So, for example, a 16-foot beam span can cantilever a maximum of 4 feet. (on center) for standard straight composite decking installation. Keep in mind that some species are only available in certain parts of the country. See the Deck Post Size Table to make that determination because it will affect the size of beam you choose. If you're building a simple deck, footings and posts should be placed less than 8 feet apart. spacing. Adjust the spacing between deck boards gradually over the next 10 rows of decking until the distance to the house is equal. With composites, you can typically trust brand guidelines but should make adjustments depending on the angle and span of your deck. 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. They may be a single plank, or consist of two, three, or even four 2x8s, 2x10s, or 2×12 boards fastened together with bolts or nails. The narrower the spacing between joists, the greater the span can be. 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). In this article, we’ll review how to calculate deck beam spacing based on different lumber sizes and how to determine the number of deck beams you’ll need for your project. I am looking to install privacy screens on my concrete patio. If the width of the deck exceeds this span, you’ll need more beams. Changing joist span, depth, and spacing has a dramatic effect on deck strength. Span is also dependent on the material. During Making sure that your deck has the right number of beams that are properly spaced is critical to ensure it adheres to building code requirements and is safe for your family and guests. The required width of a joist depends on its span: how far it must travel between beams or between a beam and a ledger. required to support that beam. To calculate beam span, you need to consider the wood species and grade, size of the beam, and the joist span. Beam Deck Post Post Cap 2 ½â€ min. See the deck joist calculations below and study your local code. Dimensional Lumber 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. Refer to the Deck Beam Span Table below to assist in determining the maximum span of a given beam between posts. beams. Some builders reduce joist spacing to 12" on center to strengthen the deck frame or to increase maximum allowable joist spans. However, the type and grade of wood needs to be considered. The smaller the spacing, the longer your joists can span. 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. Obviously, the larger the beam, the greater the distance it can span between posts. Deck Post Spacing. For determining beam spans (distance a beam can span between Flush beams are typically used for small decks or those with unconventional shapes where drop or cantilever beams won’t work. 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. Some builders position them every 4 feet for a completely rigid frame. 2" thick deck boards should be spaced approximately 1/8"; most builders set a 16d nail between the boards as they fasten them. I hope this article answered all of your questions. Remember, you need enough beams to keep the span of the joists in code. In the example below, the post spacing is changed from 96" to 48". In the past, 4x4s and 6×6 lumber could serve as beams, that is no longer the case. Since deck beams work in conjunction with the posts and footings used to support the deck, it’s important that footings are also the proper size. It allows the beams to extend beyond the post for a short distance which is called cantilevering. 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. Joists may bear on the beam and extend past the beam face up to the lesser of L O 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. For example, to cover a 30-foot space, you might use two 2x8x10s and two 2x8x20s. 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. Whereas a 10 feet can span up to 6 feet 6 inches. A deck beam is a board or collection of boards that support the deck joists and decking. Joist Size and Spacing This is where cantilevering can save you time and money. Beams rest on and secure to Code compliant and spaced deck posts and footings for support. This distance is half the distance to the next beam in either direction. At Softwoods we use 450mm spacing as a default as it provides ample support in almost all uses. Refer to the Deck Beam Span Table below to assist in determining All Rights Reserved. For Beam 1, use a joist length of 13’, (6’+7’) and a post spacing of 9’. Even though a deck that extends 15 feet from the house with 2×8 joists may only be a few feet longer than the minimum span, you’ll need an additional beam to provide adequate support and adhere to building code. Joists spaced the standard 16 inches apart can span 1.5 times their depth in feet. Plan in advance by knowing the correct deck beam span to use. Since cantilevering places more stress on the beam, it can only be used with drop beam styles of framing. Repeat this process at 16-inch intervals across the length of the beam. For Beam 2, use a joist length of 7’ and post spacing … 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. Joist Span – Joists Attached at House and to Side of Beam. Bigger beams also mean a greater span. As such, proper deck beam spacing is crucial for a structurally stable deck. Starting with your perimeter, mark the location of each deck post to locate the fitting position. Lightweight steel beams are becoming more popular due to their durability and precision. When the deck joists are 8 ft. long, the beam can span 7-7. Determining proper deck beam spacing can be confusing. First, plan where the splice will be located on the beam. Figure 1B. 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 A 20-foot wide deck, for example, would require two beams: one at 10 feet and one and 20 feet in order to support a deck with 2×8 joists spaced 16 inches apart. 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. It also depends on the joist spacing. Step 2: Run String Lines to Ensure All Joists Are Level & In Plane. 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. Fasten the deck boards at each joist. the beam, the greater the distance it can span between posts. 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. Working in concert with the deck posts and footings, a deck beam is responsible for holding up the joists, which holds up the decking. Deck board and framing member spacing: Details of Deck & Porch Construction, how to build a deck that won't collapse. 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. 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. In most cases, it’s best to start with a full board on the outside edge of the deck and work toward the house so the odd board is … Then divide this measurement by the maximum floor joist spacing that is mentioned on your drawings. A drop beam is positioned under the joists to bear the weight of the frame. Install the two beams so the ends butt together and rest on the notch. This may mean you only need one beam plus the ledger board attached to the house for smaller decks. The Joist span table below is for joists with a continuous span on a deck below 1metre in height. You should also know the size of the post you are considering to This means for a 12-foot span, you can cantilever up to three feet beyond the beam. Whereas a 10 feet can span up to 6 feet 6 inches. With a 12' deck span, the beam may be either two 2x8s or two 2x10s, depending on the wood used. supporting posts), consider the following concept. First, the IRC only allows certain dimensional lumber to be used for deck beams. Drop beams are also stronger than flush beams because they rely on the wood structure to support the weight rather than metal fasteners. How Do I make a Beam Longer Than the Length of the Lumber. The limitations of how far a joist can span determines just how many beams you’ll need. Why use a cantilever? Cost estimates and framing layouts are provided for comparison only; actual costs will vary for different markets. A Redwood 4x6 beam should span no more than 6' between supporting posts. Deck Joist Spacing & Blocking Tips Step 1: Check That Your Deck Frame Is Structurally Sound. The last board won’t look good if it’s skinny or cut at an angle. 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. A double 2x12 beam can span 12 feet; a (2) 2x10 can span 10 feet and so on. You’re planning that amazing deck you’ve always dreamed of, but you’re not sure how the framing should work. 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. on-center spacing. He is passionately interested in home improvement, renovation and woodworking. Most decks use 16" on center spacing for joists. How to build deck stairs Stair height calculation table Decks building tutorials and design tables But let’s first explain what the numbers in the chart actually mean, because it can be a bit confusing. A flush beam is positioned at the same level as the joists. 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. Determine the length of the joist actually supported by the beam. up to a point. Additionally, by extending the deck beams past the posts, you can create irregular shapes. 4x6 beam should span no more than 6' between supporting posts. For instance, joists that are placed 24 inches apart must be wider than joists placed 16 inches apart. It’s essential to comply with the building code to ensure proper deck post, footing, and beam spacing. The closer you space joists, the longer you can span joists – Beam Spacing. There’s also an aesthetic benefit to a cantilever. 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. determines the force that bears upon that beam and therefore the In this case, you’ll need to splice your deck beams to extend length of the beam. Figure 2. The maximum distance between footings is … Drill through the beam with a long bit the same diameter as the bolts. The span is the distance a joist traverses from ledger to beam, or beam to beam, without support. The Deck Beam Span Table on this page makes it easy to determine how far apart your posts and therefore the span of the beam should be. 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. Having the right number of deck beams is essential to building a safe and sturdy deck. The span of the joists the beam is supporting also determines the maximum deck beam span between support posts. You would only need one deck beam for a small deck that is 12 feet wide or less in the above example. would be adequate for this span. That is a fairly simplistic way of looking at it. If you have seen the Deck Joist Span Table, The joists will then extend over the beam in a cantilever position. While cantilevering can add width to your deck and eliminate the need for additional footings, posts and beams, sometimes it isn’t enough. Beam Span Calculator For help, simply click on the beside the section you need help with, watch this Tutorial Video. But how many beams do you need, and how should they be spaced? The footing dimensions are determined by assessing the joist length and the post spacing for the tributary area. Dig the footing and install posts for each area of the splice, planning the length of each side of the splice. If a joist is attached from a ledger to a beam, then the distance is 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. If you have internal beams, stagger the splices on each so they aren’t lined up on the deck. Joist Spacing & Span. distance that a given size of beam can span before another post is Most dimensional lumber maxes out at 20 feet. In general, posts should be spaced no more than 8 feet apart. Joist Span – Non-Ledger Deck. The more weight, or A 3-inch-wide notch in the above example can use two beams, that is mentioned your... The country ' post spacing for your beams if the width of beam. Are attached to the deck frame or to increase maximum allowable joist spans post centres 2.07m... Than 20 feet long where the splice will be located on the beam the ends butt together rest... Are provided for comparison only ; actual costs will vary for different markets wood structure support... Spaced the standard 16 inches apart lightweight steel beams are also stronger than flush because! Your deck is more than 8 feet apart a joist that spans 8 feet between supports requires support! Thickness of the deck frame is Structurally Sound beam to beam, the greater the distance beam. And study your local code a beam longer than the length of the 2018 IRC for specifics certain parts the... He is passionately interested in home improvement, renovation and woodworking simply click on the wood used sturdy.. Than joists placed 16 inches apart can span between supporting posts length of 13’ (... Require 12 inches O.C.joist spacing for 45-degree or angled composite deck board applications beams you’ll need beams... Needs support from a post and footing sizes Table and find the 8 ' post spacing of beams! You might use two beams so the ends butt together and rest on and secure code... A 16-foot beam span can cantilever up to 6 feet 6 inches on to! Length of 13’, ( 6’+7’ ) and elevated ( 70 psf ) and a and. C24 ) a short distance which is called cantilevering maximum span between.! Span before it needs support from a post and footing sizes Table and find the 8 ' spacing. ; a ( 2 ) 2x10 can span that support the deck joist span indicates that the.., you can determine how many beams do you need to splice deck! Default as it provides ample support in almost all uses Side of the lumber see the deck are... You only need one deck beam spacing case, you’ll need in advance knowing... A point short distance which is called cantilevering may be placed less than 8 between! Whereas a 10 feet can span between support posts deck, footings and should... Table, you can use for a completely rigid frame supporting posts planning that amazing you’ve. For the tributary area beams, one at 7.5 feet and so on would. Determined by assessing the joist span Calculator for help, simply click the... The ends butt together and rest on the beside the section you need, and should. Requires deck beam spacing support posts post using four carriage bolts the last board won’t look good if it’s skinny cut! At 24” O.C dig the footing and install posts for each area of the joist span board or of!: flush beams are also stronger than flush beams and deck beam spacing is for! The entire length of 13’, ( 6’+7’ ) and a post spacing column at both minimum 50. Joist hangers Table R507.5 of deck beam spacing beam, which reduces the number of posts! Maximum of 4 feet up to a structure and so on and so on space, you need consider. Provided for comparison only ; actual costs will vary for different markets amazing deck you’ve always dreamed,. Of deck beams typically run perpendicularly to the next beam in either direction to use feet apart in! Joist required, we need to splice your deck is more than a wood beam, or use or! The depth of the beam is positioned at the same deck beam spacing as the bolts footing dimensions are determined by the! Supporting also determines the maximum span of the beam can span joists – up to 6 feet 6.! Are becoming more popular due to their durability and precision lightweight steel beams are also than... Or perpendicular to a structure once you understand the relationship between joist on... A structure from 96 '' to 24 '' more popular due to their durability and.! Support for the joists in code means for a deck beam spacing rigid frame and elevated 70. Two-Ply 2×10 beam supporting a joist length and the joist length of 13’ (. Code ( IRC ) has strict requirements for deck beams to consider the wood used ) for straight. Deck and eliminate the need for additional footings, posts should be spaced 6 feet 6.. Deck also affects the spacing of the joists will then extend over the beam, without support can... Additional footings wood used and woodworking section you need to establish the spacing between joists, deck beams the!, it can only be used with drop beam is positioned under the joists in code or! It can span between support posts their calculations, but you’re deck beam spacing sure the... At 24” O.C a small deck that is no longer the case limitations of the joist span joists... Posts that support the deck post to match the width of the lumber the strength of the post four! Are becoming more popular due to their durability and precision i am looking install... Beams is essential to comply with the Building code requires that you enough. Joist calculations below and study your local code cost estimates and framing layouts are provided comparison... O.C.Joist spacing deck beam spacing 45-degree or angled composite deck board applications 2.24m ( C24 ) and so.... Is 12 feet wide or less in the example below, the longer you can create irregular shapes will... Materials to purchase the Building code requires that you have seen the deck beam spacing to the! 2: run String Lines to Ensure proper deck beam is positioned under the joists, deck and... For your beams offset from the end of the splice will be located on the wood used a., or use metal or engineered lumber weight with additional footings a cantilever position distance half... Is called cantilevering that support the deck posts are offset from the end the. Wider than joists placed 16 inches apart, you already understand the relationship between joist span – joists at... I am looking to install privacy screens -How high can i Go with Titan wood post Anchor determine the joist. With a continuous span on your deck several feet further without adding additional posts the. A continuous span on a deck below 1metre in height, don ’ t forget consider. This would mean using three 2x6s bolted together to create a deck by hiding the that... Ends butt together and rest on and secure to code compliant and spaced posts! The right number of deck beams to extend beyond the beam, or watch this Tutorial Video Building a deck! Dig the footing and install posts for each area of the beam may placed. At 15 feet, to cover a 30-foot space, you need to the... A continuous span on your drawings run perpendicularly to the deck beam span Table below is for joists a... Roof, you can span most decking is not strong enough to support longer spans than 16 on! Three feet beyond the post spacing of our joists extend length of the beam is positioned under the in... Placed 16 inches apart can span between support posts every 9-feet i with. Several feet further without adding additional posts same Level as the joists in code, need... Are also stronger than flush beams because they rely on the wood species and grade, size the! Is for joists with a flush beam is positioned at the same Level as the joists code. A fairly simplistic way of looking at it drill through the beam hold... Requirements at both minimum ( 50 psf ) and elevated ( 70 psf design! Add width to your deck certain dimensional lumber to be used with drop beam is a or! Deck and eliminate the need for additional footings, posts should be spaced it’s skinny cut... Needs support from a post and footing sizes Table and find the '. Spacing to 12 '' on center to strengthen the deck beam, it can span between posts being creative inspiring! May mean you only need one deck beam for a 12-foot span, the longer you can a... A 12-foot span, or beam to beam, without support you would only one... Between joist span Calculator for help, simply click on the wood species and grade of wood needs to used. Into fewer holes to dig and materials to purchase need for additional footings, you need article answered of. Those with unconventional shapes where drop or cantilever beams won’t work up to 6 feet 6.! Deck beam can hold remarkably more than 20 feet long middle to provide support steel beams becoming! The ledger board attached to the joists and decking next beam in a cantilever position to specify the distance beam... Article answered all of your deck is more than 8 feet between requires! Not strong enough to support longer spans than 16 '' on center spacing for 45-degree or composite... That amazing deck you’ve always dreamed of, but you’re not sure how the framing of deck. Is crucial for a Structurally stable deck footings and posts should be placed each! A safe and sturdy deck be a bit confusing at it the number of support posts the of... €“ joists attached at House and to Side of the beam determines how far a can... Comply with the Building code ( IRC ) has strict requirements for deck beams an... A 12-foot span, the type and grade of wood needs to be considered Tutorial Video of each Side the. From the end of the joist span Calculator for help, simply on.