Floor joists procurement guide
Floor joists come as solid sawn, I-joists, open web trusses or steel. Compare them by span, depth, deflection, service penetrations and documentation, not just unit price.
Floor joists support the floor deck and its loads. To procure them, specify the system (solid sawn, engineered wood I-joist, open web truss or cold-formed steel), the depth and spacing from the drawings, the bearing conditions, and the hole and notch rules for services.
Comparing joist systems
| System | Strengths | Watch for |
|---|---|---|
| Solid sawn lumber | Familiar, simple to source | Grade, species, moisture content, and span limits |
| Engineered wood I-joist | Long spans, consistent dimensions | Web hole limits, bearing stiffeners, moisture exposure |
| Open web floor truss | Service runs through the web, long spans | Layout drawings, bracing, bearing detail |
| Cold-formed steel joist | Non-combustible framing, straight members | Web stiffeners, bridging, thermal path at connections |
| Steel bar joist | Longer spans in commercial work | Typically paired with a metal deck and its own engineering |
Structural capacity depends on the full design. A table like this cannot choose for you.
What to put in the order
- Depth, flange or chord size, and spacing from the drawings.
- Product series and manufacturer, for engineered products.
- Length with allowance, and whether pieces are cut to length at the factory.
- Camber or crown requirements, where applicable.
- Hanger types and support hardware.
- Bearing lengths and any specified stiffeners.
Service holes and notches
Plumbers, electricians and mechanical trades will need to pass through the floor system. Ask the supplier for hole location charts or truss open web dimensions during design, not during installation. A hole cut where the manufacturer forbids it can reduce capacity.
Moisture and storage
Wood products should be kept off the ground, covered, and shielded from prolonged wetting, as most manufacturers warn. Steel members need dry storage to prevent surface corrosion of the coating. Review the manufacturer's handling sheet at delivery.
Documents to collect
- Floor layout showing each member.
- Product data and span tables for the series, or a sealed design where required.
- Evaluation reports or approvals if specified, via ICC-ES.
- Installation instructions, bridging and blocking requirements.
Common mistakes
- Substituting a different series for a back-ordered one.
- Cutting a flange to clear a pipe.
- Forgetting that long cantilevers and point loads need separate design.
General education only. Confirm with the engineer of record and the local authority.
Questions people ask
What is the main difference between I-joists and open web trusses?
I-joists have a solid web and limited hole zones. Open web trusses allow ducts and pipes through the open web, with the manufacturer's layout.
Is deeper always better?
Deeper members generally reduce deflection but affect story height and stair geometry. Balance with the design.
Can I drill holes in joists?
Only within the manufacturer's published limits or with the engineer's approval.
Do I need a layout?
Yes. Engineered products usually ship against a layout showing each member's location.
Sources and further reading
Have a project outline or drawings?
Organize your scope, then contact Digital Oro through its official channel. Availability, engineering, pricing and delivery terms need project-specific confirmation.
Explore Digital Oro →Digital Oro International advertises on The Company Chronicle. This guide was written by our editorial team from public sources and general professional practice; it does not describe a guarantee, quote or offer from Digital Oro International. Confirm current terms, prices and availability with the operator before you decide.