A 2×12 floor joist can typically span about 18 to 20 feet for residential use with standard loading. Are floor joists 2×4 or 2×6? Floor joists are typically not made from 2x4s due to their limited load-bearing capacity. 2x6s are more commonly used, but larger dimensions like 2×8 or 2×10 are often needed for longer spans or heavier loads.Packing is placed between the last joist and the wall at no more than 2m centres. · The floors are approximately the same level. · Packing is as close as possible&nbs...Table 502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section 311.7 provided that the design live load does not exceed 30 pounds per square foot (1.44 kPa) and the design dead load does not exceed 20 pounds ...Learn how to size and span floor joists based on the International Residential Code (IRC) and the type of lumber, species, grade, and load. Find out the factors that affect floor …When floor joists span continuously from wall to wall. (not cut at beam) this table requires that “B” be not less than 45%, or greater than 55% of “A”. Floor ...Structural - Fastening Options & Allowable Loads. Non-Structural (ProSTUD) - Allowable Loads. Allowable limiting heights & span Charts Contact ClarkDietrich Technical Services at (888) 437-3244 for any questions on tables below. Interior Framing Use iProSTUD in ClarkDietrich iTools to quickly lookup the interior framing system you need.Permissible Clear Spans for Domestic Floor Joists (to BS 5268-7.1) Imposed load. 1.5 kN/m². Strength class. C16. Note: Our floor joist span tables are based on loadings given …FLOOR JOISTS 40# LIVE LOAD 20# DEAD LOAD L/360 Table FJ-4 Design Criteria: Strength - 40 lbs. per sq. ft. live load, plus 20 lbs. per sq. ft. dead load. Deflection - Limited in span in inches divided by 360 for live load only. Span (feet and inches) 2 x 6 2 x 8 2 x 10 2 x 12 Species spacing on centerSupport conditions web direction/orientation can affect the spanning capacity of a joist. Strongbacks to be used for spans over 4m. Floor details can be found on our “Floor Joists” page. Merronbrook's easi joist span table can be used as a basic size guide for our easi-joist® to calculate the right joist for your project.Span tables for timber floor joists. Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors. These tables can help calculate whether floor joists are strong enough to support themselves and the load they carry, without the help of any walls underneath.Watch this video to see how to frame up an addition for your home, from floor joists to walls to rafters. Expert Advice On Improving Your Home Videos Latest View All Guides Latest ...Floor joist span is the distance that a structural member such as a joist can span, from one end to the opposite end. A variety of factors play into joist span, including but not limited to distance …Span and Size Charts for BCI Joists | Boise Cascade. SPAN AND SIZE CHARTS FOR ENGINEERED WOOD PRODUCTS. Learn more about Engineered Wood Products by … El = value from table above For ®TJI® 110, 210, 230, and 360 Joists Δ = +22.5 wL 4 2 El 2.67 wL 4 d x 10 5 For TJI 560 Joists Δ = +22.5 wL 2 El 2.29 wL d x 10 General Notes Design reaction includes all loads on the joist. Design shear is computed at the inside face of supports and includes all loads on the span(s). A general rule for sizing joist depth is to take half of the intended joist span in feet, add two, and then use that number in inches. For example, a 12-foot span would require a joist span of 8 inches: 12 ft. / 2 = 6. 6 + 2 = 8-inch joist span. Blocking the spaces between joists with smaller pieces of wood can reduce this stress and increase ... This page provides span tables for joist and rafters. ... Span Tables For Joists and Rafters. Back to top. Contact Us. 555 South 10th Street Lincoln, NE 68508. R502.3.1 Sleeping areas and attic joists.. Table R502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section R311.7 provided that the design live load does not exceed 30 pounds per square foot (1.44 kPa) and the design dead load does not exceed 20 pounds per ... Editor’s Note: The cantilever portion of the 2015 IRC joist span table is awkward to use. The ICC replaced the cantilever portion of the table in the 2018 IRC with a maximum overhang length making the table similar to that in DCA6. Use either the 2018 IRC deck joist span table or the joist span table in DCA6 to size joists and cantilevers.Click on a span to generate a full calculation (you can adjust the exact span). This span table is to the format and methodology given in BS 5268-7.1. These spans were calculated using our floor joist calculation engine. These span tables are the equivalent of other industry-standard span tables and are calculated to the same standards.BC Calc Benefits Summary: Easily size joists, beams, columns, studs, and tall walls. Includes BCI ® & AJS ® joists, Versa-Lam ® LVL, BOISE GLULAM ® beams, and dimension lumber. Collaborate with others and share files in the cloud or send links and project files via email. Customizable project information and user defaults.Posted on by. Find the maximum spans for ceiling joists according to the 2018 International Residential Code using the most common types of lumber with these simplified span tables. These span tables are for 16″ o.c. applications using southern pine. Plain ceilings are sized at 10 lb loads, while the ceilings with storage are sized for 20 lb ... Find the allowable joist and rafter spans for one- and two-family dwellings based on the International Building Code and International Residential Code. The span tables are based on the design values for visually graded and mechanically graded dimension lumber. This page provides span tables for joist and rafters. opens in new tab or window . Skip to main content. Quick Links. UPLNK; LNKTV City; ... Span Tables For Joists and Rafters. Back to top. Contact Us. 555 South 10th Street Lincoln, NE 68508. Connect With Us. Like us on Facebook Follow us on XFind the maximum allowable lengths of joists and rafters for different species and grades of lumber using span tables. Learn how to consider load requirements, spacing, and cost …User note: About this chapter: Chapter 8 addresses the design and construction of roof-ceiling systems. This chapter contains two roof-ceiling framing systems: wood framing and cold-formed steel framing. Allowable span tables are provided to simplify the selection of rafter and ceiling joist size for wood roof framing and cold-formed steel framing.Allowable limiting heights & span Charts · Interior Framing · Interior Ceiling Framing · Exterior Framing · Floor Joist · Web Crippling &midd...The spans are based on simple-span joists. The minimum bearing length is 1 ½”, spans values in bold indicate that web stiffeners are required at the OSB end panel. The maximum span is measured o.c. of bearings and is based on uniformly loaded joists. Dead load deflection is limited to L/360 and total load deflection is limited to L/240.Do you know how to level a concrete floor? Find out how to level a concrete floor in this article from HowStuffWorks. Advertisement You want to lay some rather nice tiles over the ...Featuring Trus Joist® TJI® Joists for Floor and Roof Applications. Timberlands. Timberlands. Trees are a remarkable resource that, when managed responsibly, can meet a wide range of fundamental needs for people and the planet for generations to come. ... SPECIFIER'S GUIDE FOR TJI 110, 210, 230, 360, AND 560 JOISTS - USA - tj-4000 . …Table values apply to uniformly loaded, residential floor joists. 2. Span is measured from face to face of supports. 3. Deflection is limited to L/240 at total load and L/480 at live load. 4. Table values are based on glued and nailed sheathing panels (23/32" for 24" o.c., 19/32" otherwise). Use an ASTM D3498 adhesive in accordance with the ...Until a few years ago, the IRC didn't have deck joist span tables. But the 2015 IRC included a new one (Table R507.5) that will make it easy for deck builders ...The LP® SolidStart® I-joist product line was sold to Pacific Woodtech (PWT) in August of 2022 in connection with our sale of our Engineered Wood Products (EWP) business and SolidStart® brand. For customer support of LP® SolidStart® I-Joists purchased prior to 8/1/2022, contact LP at 1-888-820-0325.For LP® SolidStart® I-Joists purchased on and …Floor joist span is the distance that a structural member such as a joist can span, from one end to the opposite end. A variety of factors play into joist span, including but not limited to distance …Table 502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section 311.7 provided that the design live load does not exceed 30 pounds per square foot (1.44 kPa) and the design dead load does not exceed 20 pounds per …The widest span in the floor joist span table in Part 2 of this tutorial module showed that floor joists can span 17'2" if they are 2 X 12s spaced 12" o.c. (on center). Let's expand our house beyond that 17'2" span capability to 24 feet wide. ... In general, if you are staying within the limits of your beam span tables and floor joist span ...Floor joist span tables are tabulated based on allowable deflection limits of L/360. Floor live loads range from 30 psf for sleeping areas to 40 psf for other occupancies. Ceiling joist span tables are tabulated based on allowable deflection limits of L/240. Typically a user will know the span and desired spacing for a given application.A 2×12 floor joist can typically span about 18 to 20 feet for residential use with standard loading. Are floor joists 2×4 or 2×6? Floor joists are typically not made from 2x4s due to their limited load-bearing capacity. 2x6s are more commonly used, but larger dimensions like 2×8 or 2×10 are often needed for longer spans or heavier loads.to the span in inches divided by 360, and is based on live load only. The load duration factor, C D, is 1.0. Listed spans are for wet-service conditions, pressure-treated Southern Pine floor/deck joists, MC > 19%. Check sources of supply for available grades and sizes. Maximum spans were calculated using design values effective June 1, 2013.1.1 Span and joist spacing. This demo version is fixed at 1m clear span. The full version allows any size. Joist spacing. mm. This is the distance between joist centres. Usually 400, 450 or 600mm, but any value can be used up to 610mm max.FLOOR JOIST SPANS FOR COMMON LUMBER SPECIES (Residential sleeping areas, live load = 30 psf, L/Δ = 360) For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa. Note: Check sources for availability …The size of the joists are dependant on the span between the bearers, the spacing between the joists and the type of decking used. ... As this section is quite involved, the webpage is just a guide, for full details on joists please refer to NZS3604. SG8 grade joists for wet in service use using a 2KPa floor load from table 7.1b from NZS 3604. Span Tables. SPFA provides three tables for pressure-treated Southern Pine visual grades No. 1 and No. 2, intended for use under wet-service conditions (floor/deck joists) where moisture content (MC) exceeds 19 percent. For other grades, loading conditions, and on-center spacings, refer to the SFPA’s Maximum Spans for Southern Pine Joists and ... Refer to tables for joist and beam requirements. Example a=12' Post Spacing =8'. Use the Joist Span Table to find the acceptable joist sizes for a 12' span.Sample Floor Joist Span Table. The table excerpt above is simply a sample and may not be valid for your region. Looking at this table you will see there is a choice in the size of floor joist (2 X 6, 2 X 8, 2 X 10 or 2 X 12) and there is a choice in the joist spacing (12", 16" or 14"). The floor joist spacing is the distance between the centers ...APA PRI-400. APA Performance Rated I-joists (PRIs) are manufactured in accordance with APA PRI-400, Performance Standard for Residential I-joists.This Performance Standard provides an easy-to-use table of allowable spans for applications in residential floor construction, allowing designers and builders to select and use I-joists from various … TimberStrand® LSL Floor Joists. TimberStrand® LSL is an ideal solution, providing an alternative to solid sawn floor joists, especially where longer lengths and greater stability are required. Floors work harder these days, supporting heavy kitchen islands and great rooms. Rely on TimberStrand LSL joists to deliver the loads you require. Southern Forest Products Association Span Tables. Span tables for visual and mechanical grades of southern pine lumber joists and rafters, and southern pine lumber and glue-laminated timber (glulam) headers, beams and girders. View SPC Span Tables. Photo SFPA. Floor Beam Sizing Calculator. Use the drop downs to select your floor load, framing length, and material to calculate the appropriate size of TimberStrand or Parallam beam. Calculator is for use in U.S. applications only. For Canada switch to Canada Sizing Table Lookup. Use ForteWEB™ to determine solutions for conditions beyond the scope of ...So exactly what is the difference between a rafter and a joist? Many of us have likely heard these terms without really understanding what they are and Expert Advice On Improving Y...Joist spans are based on 50 ksi for the 54, 68 and 97 mil thicknesses, and 33ksi for thinner members. Total load deflection= L/240. Live load as noted. Live load has been checked for unbalanced load contitions. Joist must be braced against rotation at all supports by track or blocking. For two equal spans, the listed span is the distance from ...Table 502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section 311.7 provided that the design live load does not exceed 30 pounds per square foot (1.44 kPa) and the design dead load does not exceed 20 pounds per …NOTE: Spans are for guidance only; for definitive information please contact an easi-joist ® manufacturer. Find a manufacturer There are numerous easi-joist® manufacturers across Europe.1.1 Span and joist spacing. This demo version is fixed at 1m clear span. The full version allows any size. Joist spacing. mm. This is the distance between joist centres. Usually 400, 450 or 600mm, but any value can be used up to 610mm max. El = value from table above For ®TJI® 110, 210, 230, and 360 Joists Δ = +22.5 wL 4 2 El 2.67 wL 4 d x 10 5 For TJI 560 Joists Δ = +22.5 wL 2 El 2.29 wL d x 10 General Notes Design reaction includes all loads on the joist. Design shear is computed at the inside face of supports and includes all loads on the span(s). When floor joists span continuously from wall to wall. (not cut at beam) this table requires that “B” be not less than 45%, or greater than 55% of “A”. Floor ...Calculate the span for floor and ceiling joist with this free and simple online calculator. The resulting spans are less than the 2012 IRC codes but they are to our standards at Scott’s …The Span Book is a supplement to the wood joist, rafter and beam spans found in the National Building Code of Canada. Tables in the Span Book and the National Building Code were both generated by the Canadian Wood Council. The National Building Code references the Span Book as follows: “Tables A-1 to A-16 cover only the most com-mon ...The size of the lumber used for floor joists is the single greatest determining factor in terms of how far a joist can span. The joist span tables start with 2×6 lumber and it goes all the way up to 2×12. For …Download the BCI or AJS I-joist Specifier’s guide to see I-joist span chart for your specific application or learn more about the Boise Cascade software suite. Floor Joist Span Chart. Find the right floor or roof joist size for your application by downloading the Specifiers Guide with detailed I-joist Span Tables.J18 Uniform Load Span Chart: · Spans are based on uniformly loaded joists and include allowances for repetitive use members. · Live loads of 40 psf assumed. · ...Use this tool to calculate the number and length of floor joists you need for any size of floor and joist spacing. You can also estimate the material cost, deflection … There is some criteria the joists must meet according o the 2012 International Residential Building Codes. The joist must have a minimum of 1 1/2″ riding on the wall or beam. If the joists are lapped, then they must be lapped at least 3″. Maximum end notches for 2 x 8, 2 x 10, and 2 x 12 respectively are 1 13/16″, 2 5/16″, and 2 13/16″. The size of the joists are dependant on the span between the bearers, the spacing between the joists and the type of decking used. ... As this section is quite involved, the webpage is just a guide, for full details on joists please refer to NZS3604. SG8 grade joists for wet in service use using a 2KPa floor load from table 7.1b from NZS 3604.Until a few years ago, the IRC didn't have deck joist span tables. But the 2015 IRC included a new one (Table R507.5) that will make it easy for deck builders ... BC Calc ® performs engineering analysis to help our customers size beams, joists, columns, studs and tall walls for their building projects. It is simple to use, yet flexible enough to analyze a variety of common applications. The user enters the member geometry, adds loads, holes and other relevant data and then selects a product for analysis. This application will specify a list of acceptable JJI-Joists once you enter your support conditions, load case and clear span. Once these have been entered, the joists suitable for this application appear in the table below. House Loading: 0.75kN/m2 Dead Load + 1.5kN/m2 Imposed Load. Flat Loading: 1.15kN/m2 Dead Load + 1.5kN/m2 Imposed Load. This page provides span tables for joist and rafters. ... Span Tables For Joists and Rafters. Back to top. Contact Us. 555 South 10th Street Lincoln, NE 68508. For content printing within Digital Codes Premium, please utilize the section level printing controls available within the Premium toolbar for each section. ICC Digital Codes is the largest provider of model codes, custom codes and standards used worldwide to construct safe, sustainable, affordable and resilient structures.• Table values based on residential floor loads of 40 psf live load and 10 psf dead load (12 psf dead load for BCI® 90 2.0 joists). • Span values assume 23/32" min plywood/OSB rated sheathing is glued and nailed to joists for composite action (joists spaced at 32" o.c. require sheathing rated for such spacing - ⅞" plywood/OSB).This application requires Javascript and WebAssembly to be enabled. <p>This application requires Javascript and WebAssembly to be enabled.</p> Southern Forest Products Association Span Tables. Span tables for visual and mechanical grades of southern pine lumber joists and rafters, and southern pine lumber and glue-laminated timber (glulam) headers, beams and girders. View SPC Span Tables. Photo SFPA. Floor joist span is the distance that a structural member such as a joist can span, from one end to the opposite end. A variety of factors play into joist span, including but not limited to distance …Joist span tables - use these tables to determine maximum spans based on the species and grade of lumber, the size of the ceiling joists (2x4, 2x6, etc.), and ...Feb 15, 2024 · The SkyCiv floor joist span calculator allows you to calculate the maximum span of timber joints. The calculations in this tool are based on the American Wood Council's standards. The floor joist calculator considers factors including the joist size, thickness, height, wood type, and wood grade as well as loading and deflection factors. TABLE 1 – JOISTS FOR 1.5 kPa FLOORS DURAGAL JOIST SPACING (mm) C450L0 4501 600 RHS SIZE2 MAXIMUM JOIST SPAN (m) Single Span Continuous Span DESIGN CRITERIA 1. Span Tables 1 to 4 & 13 to 16 have been calculated ... • The maximum spans given in Table 1 to 4 comply with the Australian Standard AS 3623 - Domestic Metal …Do you know how to level a concrete floor? Find out how to level a concrete floor in this article from HowStuffWorks. Advertisement You want to lay some rather nice tiles over the ... Find the allowable joist and rafter spans for one- and two-family dwellings based on the International Building Code and International Residential Code. The span tables are based on the design values for visually graded and mechanically graded dimension lumber. J12 (11-7/8″) Uniform Load Span Chart: J14 Uniform Load Span Chart: J16 Uniform Load Span Chart: J18 Uniform Load Span Chart: Important Notes on Span Tables: Spans are based on uniformly loaded joists and include allowances for repetitive use members. Live loads of 40 psf assumed. Additional dead loads are due to various combinations of ...Table R502.3.1(1) shall be used to determine the maximum allowable span of floor joists that support sleeping areas and attics that are accessed by means of a fixed stairway in accordance with Section R311.7 provided that the design live load does not exceed 30 pounds per square foot (1.44 kPa) and the design dead load does not exceed 20 pounds …This application requires Javascript and WebAssembly to be enabled. <p>This application requires Javascript and WebAssembly to be enabled.</p>R802.4 Allowable Ceiling Joist Spans. Spans for ceiling joists shall be in accordance with Tables R802.4 (1) and R802.4 (2). For other grades and species and for other loading conditions, refer to the AF&PA; Span Tables for Joists and Rafters. Check sources for availability of lumber in lengths greater than 20 feet. There is some criteria the joists must meet according o the 2012 International Residential Building Codes. The joist must have a minimum of 1 1/2″ riding on the wall or beam. If the joists are lapped, then they must be lapped at least 3″. Maximum end notches for 2 x 8, 2 x 10, and 2 x 12 respectively are 1 13/16″, 2 5/16″, and 2 13/16″. You can make ads in the Engineering ToolBox more useful to you! Maximum floor joist span for No. 1 and No. 2 Grade of Douglas fir are indicated below. Max. dead load (weight of structure and fixed loads) 10 lbs/ft2 . Live load is weight of furniture, wind, snow and more. Max. Live Load 30 lbs/ft2(1436 N/m2) Max. Live Load 60 lbs/ft2(2873 N/m2) Allowable roof snow load rafter spans are based on design snow loads. Ground snow loads must be converted to design snow loads for roofs in accordance with appropriate building code provisions before using the tables. ... BUYERS GUIDE. WESTERN LUMBER. LIBRARY. ABOUT WWPA. LOGIN. Top Pages. DOUGLAS FIR. SPANS. MOLD ON …May 26, 2009 ... I'm constantly working with 80-100 year old ACTUAL dimension pine floor joists. 2x8 are actually 2x8, the 2x10s actual 2x10s. Description: Featuring Trus Joist® TJI® Joists for Floor and Roof Applications. Document ID #: tj-4000. File Type: pdf. File Size: 5.1 MB. File Date: October 2023. Document Types: Design & Specification Categories. Engineered Lumber; Products. TJI® Joists Aug 23, 2017 ... Based on a pre engineered metal web joist system by ITW Construction Products known as the SpaceJoist, the table shows the spans they can reach ...Nov 23, 2021 · How to Use Floor Span Tables 1. Choose the appropriate live and dead load combination as well as a joist spacing. 2. Scan down the spacing column to find a span that exceeds the design span. 3. Scan to the left from that span to determine the joist size required. 4. Web stiffeners are required at all supports for 22" and 24" joists. While most residential construction uses 2x8 joists with 16 inch spacing, there are many other factors you need to consider when determining the proper joist span length. Joist span and spacing is set by your local building code. You should check with your local building department for construction requirements in your area.
A 2x10's maximum span depends on where it's used. According to IRC 2021, a 2x10 with 16-inch spacing can span up to 18'-9" as floor joists, more than 26' as rafters and ceiling joists,4'-3" as beams, and 7' as headers without providing additional support. These values apply to Southern Pine Species. This article lists the maximum span of 2 x …. How much does a venti cost at starbucks
A 2×12 floor joist can typically span about 18 to 20 feet for residential use with standard loading. Are floor joists 2×4 or 2×6? Floor joists are typically not made from 2x4s due to their limited load-bearing capacity. 2x6s are more commonly used, but larger dimensions like 2×8 or 2×10 are often needed for longer spans or heavier loads.• Table values based on residential floor loads of 40 psf live load and 10 psf dead load (12 psf dead load for BCI® 90 2.0 joists). • Span values assume 23/32" min plywood/OSB rated sheathing is glued and nailed to joists for composite action (joists spaced at 32" o.c. require sheathing rated for such spacing - ⅞" plywood/OSB).When planning for retirement, many people underestimate just how long they'll live. When planning for retirement, many people underestimate just how long they'll live. That's t...The SFPA’s tables list maximum spans for Southern Pine joists and rafters assumes the quality of wood products and fasteners, and the design of load-supporting members and connections, conforms to the National Design Specification® (NDS®) for Wood Construction published by the American Wood Council (AWC).All members must be framed, …Dec 28, 2007 ... For other grades and species and for other loading conditions, refer to the AF&PA Span Tables for Joists and Rafters, ... FLOOR JOIST SPANS FOR ... Span Tables. SPFA provides three tables for pressure-treated Southern Pine visual grades No. 1 and No. 2, intended for use under wet-service conditions (floor/deck joists) where moisture content (MC) exceeds 19 percent. For other grades, loading conditions, and on-center spacings, refer to the SFPA’s Maximum Spans for Southern Pine Joists and ... MILLIMAN S&P 500 1-YEAR FLOOR WITH PAR UP FUND - FEB CLASS 3- Performance charts including intraday, historical charts and prices and keydata. Indices Commodities Currencies StocksThis ceiling joist span table is based on the 2012 IRC for uninhabitable attics with limited storage. It covers #2 common lumber species and sizes at 20 pounds per square foot load. Although 2 x 4’s are included in the official table, they are not listed because it is never advised to use them. 2 x 12’s are not listed because you can span pretty much whatever …For all other additional loads, joist sizes should be designed by an engineer in accordance with Technical Requirement R5. Table 1: Permissible clear spans for domestic floor joists. Strength class C16. Imposed load not exceeding 1.5 kN/m2. Service class 1 or 2. Table 2: Permissible clear spans for domestic floor joists. Strength class C24 ...Span tables for Kerto® LVL beams, panels, studs and I-joists help designers work faster and more efficiently. The tables below describe the most common measurements according to local requirements for different Kerto LVL structures in floors, roofs and walls. By using these tables you can find the most optimal cross-sections for the structures ...Openings in floors shall be framed with header and trimmer joists. Header joist spans shall not exceed 6 feet (1829 mm) or 8 feet (2438 mm) in length in accordance with Figure …Floor Span Tables: 40 psf Live Load and 10 psf Dead Load TO USE: 1. Select the Simple Span or Continuous Span table, as required. 2. Find a span that meets or exceeds the required clear span. 3. Read the corresponding joist series, depth and spacing. CAUTION: For floor systems that require both simple span and continuous span joists,R802.4 Allowable Ceiling Joist Spans. Spans for ceiling joists shall be in accordance with Tables R802.4 (1) and R802.4 (2). For other grades and species and for other loading conditions, refer to the AF&PA; Span Tables for Joists and Rafters. Check sources for availability of lumber in lengths greater than 20 feet.A general rule for sizing joist depth is to take half of the intended joist span in feet, add two, and then use that number in inches. For example, a 12-foot span would require a joist span of 8 inches: 12 ft. / 2 = 6. 6 + 2 = 8-inch joist span. Blocking the spaces between joists with smaller pieces of wood can reduce this stress and increase ....