Choosing a floor joist involves more than finding a member that reaches between two supports. A floor joist span table brings together several design inputs, including the design span, joist spacing, loads, deflection limits, bearing and flooring requirements.
Quick answer: Use a span table to shortlist an I-joist, then confirm that every table assumption matches the project. If the layout or loading falls outside the table’s scope, use the appropriate project-specific design and documentation pathway.
Check the Dindas Interactive I-Joist Span Tables
What does a floor joist span table tell you?
A span table shows which members may suit a defined set of conditions. It is not a generic answer to “How far can a floor joist span?” The result changes when the table assumptions change.
Before selecting a member, check:
- whether the joist is single-span or continuous
- the internal span measurement between structural supports
- joist spacing or centres
- dead, live and point-load assumptions
- the required deflection or floor-performance criteria
- minimum bearing and flooring requirements
- any cantilevers, concentrated loads or other project-specific details
A member shown for one combination of span and spacing should not be applied to a different combination without checking the relevant documentation.
What affects I-joist size and spacing?
Joist depth and flange series work together with spacing and loading. Deeper or different-series members may be available for more demanding layouts, but size alone does not establish suitability.
The current DindasJoist range includes depths from 190 to 400 mm and flange-width options of 45, 52, 58 and 90 mm. Not every depth is available in every flange series, so the final selection must match the current product information and span-table result.
DindasJoist is intended for internal floor systems and roof rafters in residential and light commercial buildings.
How to use the interactive I-joist span tables
When using the DindasJoist interactive span tables:
- Check the span condition
Confirm that the joist is single-span. The span distance is measured internally between the structural supports. - Select the relevant project inputs
Choose the building type, floor dead load and preferred deflection that match the project requirements. - Review the joist results
Check the recommended DindasJoist member and maximum joist centres. The selected flooring must also be suitable for the nominated spacing. - Check the complete floor system
Review the stated loads, bearing, restraint, flooring and other installation requirements before carrying the selection into the project documentation. - Confirm the final selection
The interactive results provide preliminary guidance and are not construction documentation. For continuous spans, non-uniform loading, cantilevers or other conditions outside the tool’s scope, refer to the current DindasJoist design documentation or request project-specific support.
Installation details still affect the floor system
Correct selection is only one part of floor-system performance. Storage, moisture exposure, bearing, restraint, flooring installation and service penetrations must follow the current guidance.
Holes for plumbing, electrical or mechanical services must comply with the Dindas I-joist web-hole charts. Never drill, cut or notch an I-joist flange, or over-cut the web.
See the correct method for cutting Dindas I-joist web holes
Check Dindas technical resources
When should you request design support?
Request project-specific design support when the floor system cannot be represented accurately by the available span-table assumptions or requires coordinated layouts and documentation.
Start with the interactive span tables to narrow the options, verify the assumptions and obtain additional support where required.
