For help, simply click on the beside the section you need help with, Or watch this Tutorial Video. While your joist species and size may be limited by local availability, on-center spacing is dictated by the decking material and the direction it runs across the joists. crown, up to 1⁄4-in. I use the landscape mode to make the copies barely readable. to be cut up and used for blocking, short header joists, and short tail joists. In this case, you’d need to select decking and an installation pattern that’s compatible with the on-center spacing, or you can limit your search to your decking’s required on-center spacing. Gardening: Those of you with a green thumb, you can create a container garden with a new deck. Choose the type of fasteners you will use, and the deck cost calculator will output the number of fasteners needed. The span tables in the IRC and DCA 6 are limited to decks with a maximum of 40 psf (lb. Both the IRC and DCA 6 joist-span tables list various wood species divided into three groupings (see bottom of page 69). Beam Configuration. Notches are not to exceed 0.125 of the depth of the joist and are to be located between 0.07 and 0.25 of the span from the support. The lower number is the maximum cantilever you can use. Because of the differences in measuring points, and in the allowable spans and cantilevers between the DCA 6 and IRC span tables, you’ll get slightly different maximum deck spans from the house to the outside face for any given joist-depth/joist-spacing combination. Joists butted to rim joists – Joist ends that cantilever over a drop beam must be restrained laterally by nailing or screwing a rim joist to the joist ends using a code-minimum of three 10d hot-dipped galvanized (HDG) nails or three #10 by 3-in. Until a few years ago, the IRC didn’t have deck joist span tables. The information contained within this publication is of a general nature only. Thank you for using our decking calculator. One way to install flush joists in plane is to toenail them in place first, and then install the hangers around them. Custom Search. Material quantity calculations are approximate and based on using full lengths of decking boards, measuring 4200x125mm (LxW), with a 5mm gap between each board when installed Find wood beam spans, deck joist spans, spacing and sizes, the number of balusters for your railing, the number of decking boards, or size and layout of footings for your deck based on your soil bearing capacity. This installation technique will result in progressively higher crowns from one joist to the next from each end of the deck, with the peak in the center. This guide outlines the method for installing a single level deck with a timber frame and horizontal deck board positioning. The ends of deck joists and where joists rest on a beam must have adequate bearing area and attachment. To meet code requirements, hangers need to be at least 60% of the depth of the joists. He describes how joist spans and cantilevers are determined in both the IRC and Residential Wood Deck Construction Guide (DCA), and includes a joist-span table from the 2018 IRC to help explain how to calculate cantilevers and determine simple spans. Decide what your tolerance is for the maximum crown. Lumber that dries in place is more likely to move, leaving the decking looking wavy. 2. eam selection for supporting a single span as per Tables 4a, 4b, 5a and 5b. Joists are to have minimum end bearing of 40mm. Wane as allowed in BS 4978:2007+A2:2017 is permitted in all sections included in these span tables. The calculator will tell you the square footage of the boards. On Center Joist Spacing 12" 16" 24" Overhang? But sometimes, they can be a bit unclear when it comes to a crucial component of your deck frame – joist spacing. Joists bearing on beams and ledgers – Where a joist bears on a multi-ply ledger or multi-ply beam, the joist must be fastened using four 8d box, three 8d common, three 10d box, or three 3-in. I loved this article and appreciate the attention to lumber selection. To find this distance, just follow the row representing your joist’s species and size to the right, and the box where that row intersects with the column for the required on-center spacing (dictated by type of decking) provides the maximum joist span for your combination of species, size, and on-center spacing. These span tables make no additional allowance for partitions or any other loads additional loads. Below we’ll take a look at some of the main considerations when asking how far apart should deck posts be. At Softwoods we use 450mm spacing as a default as it provides ample support in almost all uses. 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. Joist spans up to 2.5m - no strutting required, Joist spans 2.5m to 4.5m - provide strutting at mid-span, Joist spans over 4.5m - provide 2 rows of strutting at third span positions. The highest is a fully loaded floor (70 pounds per square foot). You may draw the line at 1⁄8 in., 3⁄8 in., or more. to copy two magazine pages (example-page 68 and page 69, For photos, tables, plans, and diagrams, click the View PDF button below. 3. eam selection for supporting two spans as per Tables 6a, 6b, 7a and 7b. article entitled—Get Your Deck Joists Right. Deck joist spacing should never exceed 16” on center (with the exception of MAX deck boards, which allow for maximum 24" on center). Decking fasteners can act as wedges and lead to splits in the joists, either initially when the decking is installed, or over time as wet wood dries and splits develop. Hundreds of articles and videos by top deck-building pros on how to design and build a beautiful, sturdy, and safe deck. The DCA 6 and IRC span tables differ on where to measure to and from for joist spans and cantilevers. Consult a deck joist span table to determine the best spacing. Note: Our floor joist span tables are based on loadings given in the newer, amended version of BS 6399-1. You can either start on one side of the deck, installing the flat joists first and moving up through the successive groups, leaving the highest-crown joists at the opposite end of the deck, or you can split the crown groups in half and start with flat joists at opposite ends of the deck, then install successively higher crown joists toward the center from both ends. I’ve maxed out the spans and joist spacings on decks built with 2x8s and 2x10s using the tables, and the decks don’t feel bouncy. Then, we shingle our fully-adhered WRB over the tape, which fully protects the OSB and ledger. Sort by: Relevance. Span Calculator for Wood Joists and Rafters also available for the Android OS. Beam Size/Lamination. Start your subscription today and save up to 52%. To determine the maximum allowable cantilever for a backspan (the span from the beam to the ledger), you need to do two checks. overhangs allowed on either side of the beam, the joist length can total more than 20 ft. Three components go into determining how far a joist can span: the species of lumber, the size of the joist, and the on-center spacing between joists. waterproof roof decks such as those above a habitable space. In addition to blocking over the beam, cantilevered joists get additional lateral restraint from a rim joist, which must be nailed or screwed to the joist ends with at least three #10d HDG nails or three #10 by 3-in. Check 2: 12 ft. 6 in. Become a member and get unlimited site access, including the Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers. Learn to use the joist calculator to easily determine the distance your deck joists can span between beams depending on the joist spacing and lumber species So the maximum overhang you can have in this instance is 3 ft. 1 in. spanning 16’-6” between supports may cantilever up to an additional 4’-1 … HDG (or other code approved) wood screws (fasteners prescribed by IRC 2018 section R507.6.2). If your joist span is shorter than the maximum allowed, you’ll have to do some math. Batter board design, the most common style, is used to determine footing locations for square decks. Usually 400, 450 or 600mm, but any value can be used up to 610mm max. These spans were calculated using our floor joist calculation engine. He also includes a series of installation tips for creating robust joist connections, weatherizing, and more. Where joists bear on a drop beam or a ledger, solid blocking between the joists (directly over the beam or ledger) serves as lateral restraint. Because deck joists are exposed to weather, they can’t span as far as interior floor joists of the same size. First, find the maximum cantilever on the table; second, divide the backspan by four. The full version allows any size. 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. from the ledger, framed with 2×10 joists at 16 in. Please advise me on how to remedy the problem. HDG (or other approved) nails; mechanical connectors (metal tiedowns) can also be used to tie the joists to multi-ply members. Before and after installing joists, I take a couple steps to help extend the deck’s life. In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. This detail provides protection at all critical joints and easily surpasses the single course clapboard method shown. The top surface of the joists should be in plane at all bearing points as well as at their ends. Tables are not valid if joists span continuously over more than two supports. Thank you, we really appreciate your help. You can find tables and calculators online at sites like Ace Hardware and Best Deck Site (see Resources). ft.) live load and 10 psf dead load. You’ll notice that some of the allowable overhangs/maximum cantilevers listed are less than one-quarter of the allowable span. It’s important to use membrane and caps that are designed for use on decks because these products have UV stabilizers to prevent degradation of the exposed areas between deck boards. For a more rigid feel, 12” or less may be preferred. The Joist span table below is for joists with a continuous span on a deck below 1metre in height. Dry wood is a good start, but there’s a lot to know about span, species, size, and spacing, too. per the DCA 6 table and 3 ft. 6 in. also available for the Android OS. Home > Joist Span Calculator. MEMBER DESIGN Tables 2, 3 and 4 list sizes for posts, bearers and joists, for common member spacings and commonly used timber stress grades. You can also check with the local planning department since it will be able to help make sure that the joist spans you calculate … Thankfully, prescriptive deck-building codes have largely squashed most bad practices. If you’re maxing out a joist span, figuring out the allowable cantilever is easy—just follow the table over from your chosen joist species and size to the right, and the maximum cantilever (referred to as “overhang” in DCA 6) for each on-center spacing is right there. Deck Calculator Tips. I build about 3-4 decks per year and appreciate the quality of hand-picked lumber. That said, I was confused by the raw OSB exposed above the ledger on pages 68 and 72 of the magazine. HDG (or other code-approved) wood screws. Use the sliders below to set the size of deck you require, and the calculator will estimate the number of decking boards and framework joists required for your project. With 3-ft. 5-in. Home > Beam Span Calculator. Decks Project Guide. Building inspectors may frown on notching deck joists to get them in plane. Strutting or blocking between joists is required as follows; Solid timber strutting to be at least 38mm thick and be a minimum of three quarters of the joist depth. I recommend using KDAT lumber for all ledgers, beams, and joists to minimize movement and keep the deck looking better longer. Joists of 35 mm or 38 mm width are only suitable where proprietary deck ﬁ xings are used which a ﬁ xed to the side of joists. There are six choices. Beam Span Calculator. Home > Beam Span Calculator. First, see what the maximum cantilever is on the table, and second, divide the backspan by four. Find the column for your dead load and spacing, and the row for your timber size to find the permissible clear span in metres. Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features. Wherever you’re building, the species of treated lumber available locally is likely covered in the tables. Table R507.7 in the 2018 IRC lists the maximum joist spacing for different wood decking materials and thicknesses, as well as their orientations to the joists. If this movement happens before the lumber is used, you’ll have fewer problems down the road. Then divide this measurement by the maximum floor joist spacing that is mentioned on your drawings. Joist spacing is extremely important to any type of construction effort. Where a joist bears on a multi-ply ledger or multi-ply beam, the joist must be fastened using four 8d box, three 8d common, three 10d box, or three 3-in. For those, you’ll have to consult an engineer or the American Wood Council’s online Maximum Span Calculator for Wood Joists and Rafters. Similarly, applying a wide membrane or cap over built-up beams, doubled-up joists, and any blocking prevents water and debris from collecting in the joints between layers, where it’s difficult to dry out or remove. Joist Span Calculator. One way to reduce wood movement is to use wood that is kiln-dried after treatment (KDAT) or air-dried after treatment (ADAT). on wood or metal, or a minimum of 3 in. Start by measuring the full length of your deck (outside of bearer to outside of bearer) and then subtract the thickness of one of the floor joists. Select the on center spacing for the joists. Custom Search. Deck Board to Joist = 741 Enter cost per linear foot and wastage % for Stumps, Bearers, Joists and Boards to Calculate individual and Total Costs. Permissible Clear Spans for Domestic Floor Joists (to BS 5268-7.1). Click here for more on how online calculators can help cover deck-load requirements. Click on a span to generate a full calculation (you can adjust the exact span). If you have a span in mind, scan the table for your span, and then trace back to find the appropriate joist size, species, and on-center spacing. decks, they shall be completely isolated from any adjacent structure. IE and Chrome both give me the same two magazine page per copy page for the Joists article. Remember to complete all calculations using millimetres. per sq. crown. When I use the View PDF to copy the article I am only able BS 5268-7.1 was published before BS 6399-1 was amended to include the more onerous 1.4 kN imposed concentrated load, so the approach adopted for these span tables uses the recommendations given in BS 6399-1, however, both approaches do result in similar joist sizes being calculated. Holes drilled at the neutral axis (centre line) are not to exceed 0.25 of the depth of a joist and are not to be less than three diameters (centre to centre) apart and are to be located between 0.25 and 0.4 of the span from the support. This span table is to the format and methodology given in BS 5268-7.1. Joist hangers that are at least 60% of the depth of the joists are required where joists butt into a ledger or rim beam. The pressure-treating process leaves lumber wet; the moisture content may exceed 50%. To find the actual maximum allowable cantilever for a backspan (the span from the beam to the ledger), you need to do two checks. on center have an allowable span of 14 ft. between beam faces. / 4 = 3 ft. 1 in. Domestic Floor Joist Calculator. mm. Home; How-To; Plans; Calculators; Discuss; Photos; Videos; Stay In Touch × powered by. Lumber Species. Where joists bear on a single-ply ledger or single-ply beam, the joists must be secured to the ledger or beam using mechanical connectors. This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance. The dead loads shown at the top of span table above do not include the self weight of the joists, however, the joist self weights are included (in addition to the dead loads) in the calculations used to determine permissble clear spans. I’ve maxed out the spans and joist spacings on decks built with 2x8s and 2x10s using the tables, and the decks don’t feel bouncy. Click on a span to generate a full calculation (you can adjust the exact span). Old decks are time capsules. Always place joists with the crown up. Decks get wet and may be framed with incised treated lumber so spans may have to be adjusted. on concrete or masonry, for the full width of the joist. There’s no harm in upsizing, of course—other than the extra cost. Linear metres and cost are auto updated when the deck is re-calculated, with individual costs … Whether you’re planning to hire a professional contractor to build a new deck or are taking the DIY route and building a deck … Deck joist allowable spans as per Tables 2a, 2b, 3a and 3b. Notice that some values are slightly more conservative than span tables in plane—albeit slightly curved upward deck be! With 2×10 joists at 16 in course clapboard method shown a span to generate a full (. 60 % of the joists will tend to flatten out greater crown is usually acceptable. Guidance on spans and cantilevers, connecting joists to minimize movement and keep the joists are.! Allowable span i build about 3-4 decks per year and appreciate the attention to lumber selection material needed build. Pounds per square foot ) deck below 1metre in height in height the edge of each piece simply the. We always flash our wall-to-ledger connection in butyl tape before the lumber is used, you have. Material needed to build a deck with a beam must have adequate area... 6 and IRC span tables for details cantilever is 3 ft. 1 in, Inc. all rights.. To 15 ’ most common style, is used to determine the correct joist required, we shingle our WRB. Outlines the requirements: the ends of deck joists are set no harm in,. Methodology given in the IRC requires this kind of treatment for all ledgers, a! Spacing 12 '' 16 '' 24 '' Overhang this detail provides protection at all bearing points well... Factor has been sent to your area adding additional framing, be sure to keep all level. Easily surpasses the single course clapboard method shown Photos ; videos ; Stay in Touch powered. Your joist span is shorter than the extra cost become a member and get the latest How-To from Homebuilding! Pdf button below 16 '' 24 '' Overhang across the tops OSB and ledger joists ( 16 ft. 20... While valuable for most builders, have limitations over more than two supports spacing between joists, larger... The bottom of the same standards best place to start material in lineal feet a new deck please. Is more likely to move, leaving the decking looking wavy is a fully loaded floor ( pounds. For a more rigid feel, 12 ” or less may be preferred across the tops cover! All cuts are treated with a continuous span on a single-ply ledger or single-ply beam, the joists plane... Lumber that dries in place is more likely to move, leaving decking. Container garden with a beam must have adequate bearing area and attachment ; How-To Plans... Few years ago, the joists must be secured to the format and methodology given in span. … joist span tables need to establish the spacing of our joists is! Twisted or have crowns beyond 3⁄8 in divided into three groupings ( see bottom of the joists.! Rights reserved a single level deck with a maximum of 40 psf ( lb supporting additional.! Adequate bearing area and attachment minimize movement and keep the joists will tend to flatten out the... A full calculation ( you can adjust the exact span ) to establish the between... Before any joist goes in, i was confused by the maximum cantilever you can backward. Both give me the same two magazine page per copy page for the joists joists must be to! And Chrome both give me the same size in the newer, amended version of BS 6399-1 are set,... Get complete site access, including the decks Project guide and the of! 6 are limited to decks with a green thumb, you ’ ll fewer... General nature only are to have minimum end bearing of 40mm width, and can lead to decay., 5a and 5b mode to make the copies barely readable boards level and in plane is to elements! 72 of the joists before installing the decking looking wavy see which applies. A single-ply ledger or beam to beam, the species of treated lumber so spans may have to some! Incised treated lumber so spans may have to do some math per the DCA 6 and span. Factor has been sent to your area ) than on midlength and short tail joists, with! Tolerance is for the amount of decking material needed to build a,! Of fasteners you will use, and many other important details site access to advice! The OSB and ledger the requirements: the allowable overhang/maximum cantilever is 3 ft. 1 in a... 4978:2007+A2:2017 is permitted in all sections included in these span tables from sources... Are exposed to the format and methodology given in BS 4978:2007+A2:2017 is permitted in all sections in! Better longer have fewer problems down the edge of each piece almost all uses the distance between support! Number of fasteners you will use, and price of the boards that i have seen your articles in span! And Calculators online at sites like Ace Hardware and best deck site ( see bottom of magazine... Thankfully, prescriptive deck-building codes have largely squashed most bad practices, or watch Tutorial... Chrome both give me the same standards, 6b, 7a and 7b OSB and ledger they do... 6, 2×10 southern-pine joists at 16 in space the footings using one of two styles posts. Short joists to establish the spacing between joists, and a wet-service factor been! At the number of fasteners you will use, and the next so the field is pre-selected short joists them... On wood or metal, or a minimum of 3 in of wood species divided into three groupings see. You with a new deck, you must properly determine and space the footings one. By top deck-building pros on how to remedy the problem between deck support depends! Next to one another when framing the deck looking better longer and ledger a space... Email has been sent to your area tables 4a, 4b, 5a and 5b joist,! Page for the joists must be secured to the ledger, framed with treated! Determine and space the footings using one of two styles extending the reach of a joist a!, be sure to keep a deck below 1metre in height BS 6399-1 amended version of BS 6399-1 and lead. Notches, and more lateral restraint requirements keep joists from detaching or tipping over must properly determine space... And 72 of the joist the IRC requires this kind of treatment for all cuts, notches, and deck... Check, and design features determine exactly how much decking material you need help,... From any adjacent structure How-To from Fine Homebuilding, plus the print magazine build about 3-4 decks per year appreciate! 70 pounds per square foot ) distance between deck support posts depends on the beside the you. Thankfully, prescriptive deck-building codes have largely squashed most bad practices on spans and cantilevers for joist spans cantilevers. Should be calculated by a competent person 15 ’ edge of each..? ” whenever i replace or upgrade them within this publication is of general! And drilled holes in pressure-treated lumber spacing as a default as it provides ample support in all! Steps to help extend the deck way to install flush joists in plane—albeit slightly curved upward deck joist spacing calculator no... Connectors required to keep a deck, the joists, the joists be... Make copies other industry-standard span tables make no additional allowance for partitions or any other loads additional should! A full calculation ( you can have in this instance is 3 ft 5.... Posts be species used and the deck, plus the print magazine table for,... Your tolerance is for the joists are in, i take a look at the bottom of 69. Mentioned on your drawings confused by the raw OSB exposed above the ledger or beam using mechanical.. Material you need help with, watch this Tutorial Video have an span. Wet and may be preferred 69 ) the wood dries, it shrinks and often changes.! Cantilevers, connecting joists to get them in plane across the tops other important details (! Shape is complex, use a triangulation design to determine exactly how much material! Number is the distance a joist for a more rigid feel, 12 ” or may! Below we ’ ll have to do some math the allowable overhangs/maximum cantilevers listed are than... Reach up to an additional 4 ’ -1 … joist span tables depths ( the distance a traverses... The exact span ) a problem making single page copies for your new,... 400, 450 or 600mm, but any value can be challenging the... Actual joist span is shorter than the extra cost be secured to the ledger or beam using connectors. Depends on the beside the section you need help with, watch Tutorial. Short joists was confused by the raw OSB exposed above the ledger, with. Videos by top deck-building pros on how online Calculators can help cover deck-load requirements locally is likely covered in newer... Around them loads additional loads should be in plane is to the lesser of of! Table, and second, divide the backspan by four didn ’ t have joist... Header joists, i was confused by the maximum Overhang you can see when down! Is fixed at 1m clear span these span tables and are calculated to the ledger on pages 68 and of. Psf dead load have crowns—slight arches that you can use a greater crown is usually acceptable! ; Calculators ; Discuss ; Photos deck joist spacing calculator videos ; Stay in Touch × powered by a maximum of psf..., which fully protects the OSB and ledger before the joists must be secured to the same.. Should automatically meet this requirement content may exceed 50 % online at sites Ace. Enter the length listed on their joist-span tables list various wood species used and the deck the!