# AS 1684 Span Tables Explained: Start with the Inputs Learn how to choose the applicable timber-framing reference and read a span-table result in its full design context. - Canonical HTML: https://www.chippy.tools/building-codes/au/framing/as-1684-span-tables-explained/ - Publisher: Chippy Tools - Updated: 2026-09-06 - Market: au - Code edition / reference: NCC 2022 reference pathway - References: NCC22 H1D6; AS 1684.2; AS 1684.3 - Scope: Australian housing framing: reading plans, references and product details. No permitted member spans are supplied. - Source text checked: 2026-09-06 - Review scope: Public source text checked for this explanatory guide. No licensed span-table values or project design are verified. ## Start with the design inputs An AS 1684 span table gives an answer for a defined framing case. The timber grade, member size, loads and supports must match that case. This guide helps you collect those inputs and read the result. It does not supply permitted spans. ## Choose the right framing route [NCC 2022 H1D6(4)](https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two/h-class-1-and-10-buildings/part-h1-structure) lists several timber design routes. The AS 1684 split is: | Reference | What the NCC calls it up for | |-----------|-------------------------------------------------------------| | AS 1684.2 | Residential timber framing in non-cyclonic areas | | AS 1684.3 | Residential timber framing in cyclonic areas | | AS 1684.4 | Simplified residential timber framing in non-cyclonic areas | Each part has its own scope. H1D6 also lists AS 1720.1 for timber design and AS 1720.5 for nailplated roof trusses. These are not interchangeable sets of tables. A design outside an AS 1684 route needs a route that covers it. Use the edition called up for your job, including state changes. These clause links refer to NCC 2022. Start at the [Australia hub](https://www.chippy.tools/building-codes/au/) to check the local code context. A newer book on sale does not by itself change an approved design. ## Read a table as a complete entry Keep this input list beside the plans. Some tables use load width; others need a different load measure. Use the headings and sketch for the chosen member. | Input | What to match | |-----------|-------------------------------------------------------| | Member | Joist, bearer, rafter, lintel or other named member | | Timber | Grade, actual section and product type | | Layout | Spacing, span case, supports and any overhang | | Loads | Floor or roof loads and the stated load measure | | Wind | The job’s assessed wind class where the table uses it | | Reference | Part, edition, supplement, table and all notes | A cropped row loses the facts that make the answer useful. Keep the table heading, notes and support sketch with your record. Use the table’s definition of span. Do not treat a stock length as a permitted span. ![Four checks: choose the code route, match member inputs, read the full table, and record the design reference.](https://www.chippy.tools/building-codes/au/framing/as-1684-span-tables-explained/workflow.svg) **Diagram labels:** READ A SPAN TABLE; CHIPPY TOOLS; READ A SPAN TABLE; 1; Choose the route; Code edition, state and standard; 2; Match the inputs; Member, grade, layout and loads; 3; Read the full entry; Table heading, support sketch and notes; 4; Keep the record; Plan version and design reference *Chippy Tools reading checklist. Code routes: NCC 2022 H1D6(4). No licensed table or span values are reproduced.* ## A useful check before ordering Suppose the plan calls for a joist over a middle support. The supplier sends a single-span table entry. The stock may look right, but the support case does not match. Ask for the correct entry or a checked design detail before ordering. Do the same if the grade or floor finish changes. Record the plan version and member mark beside the table reference. Keep unresolved questions with that record. A member size alone leaves out the joints, bracing and rest of the frame. ## Next steps Read the [joist input guide](https://www.chippy.tools/building-codes/au/framing/floor-joist-spans-explained/) or [rafter guide](https://www.chippy.tools/building-codes/au/framing/rafter-spans-and-roof-members/) for the member you are checking. Use the [Chippy Tools code-check sheet](https://www.chippy.tools/building-codes/printables/#code-check) to keep the source and plan details together. ## Sources - [NCC 2022 H1D6(4): timber framing routes](https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two/h-class-1-and-10-buildings/part-h1-structure) Publisher links identify the standards. This review did not inspect or reproduce their licensed span tables. - [AS 1684.2:2021 publisher catalogue](https://store.standards.org.au/product/as-1684-2-2021) - [AS 1684.3:2021 publisher catalogue](https://store.standards.org.au/product/as-1684-3-2021) - [AS 1684.4:2010 publisher catalogue](https://store.standards.org.au/product/as-1684-4-2010) Content adapted from the National Construction Code 2022, provided by the Australian Building Codes Board under the CC BY 4.0 licence. This page is general information for tradespeople and is not compliance, engineering or legal advice. Requirements are subject to state and territory variations and adoption timing. Always confirm requirements with your building certifier and relevant state authority. ## Frequently asked questions ### Where can I get AS 1684 span tables? Use Standards Australia or an authorised standards provider for the part and edition your design requires. This guide links the publisher catalogue and explains the inputs; it does not reproduce the licensed tables. ### What is the difference between AS 1684.2, .3 and .4? NCC 2022 H1D6(4) lists .2 for non-cyclonic timber framing, .3 for cyclonic framing and .4 for the simplified non-cyclonic route. Each part has scope limits. Check the edition and state rules that apply to your job. ### Can I use the same row for a different timber grade? Do not carry a table result across to another grade or support case. Match all inputs and notes, or ask the designer to check the change. ## Source-check references - [NCC 2022 H1D6(4): timber framing routes](https://ncc.abcb.gov.au/editions/ncc-2022/adopted/volume-two/h-class-1-and-10-buildings/part-h1-structure)