Light steel frame buyer guides
Floor Systems for Multi-Storey Light Steel Frame Buildings
Multi-storey light steel frame buildings use several floor types, from steel joists with a panel subfloor to concrete over steel deck. Compare what each does for span, sound, fire and speed.
The floor does more work in a multi-storey building than in a house: it carries people and partitions, spans between walls, acts as a diaphragm that passes wind and seismic loads to the walls, and separates dwellings for sound and fire. Choosing it is a system decision, not a joist purchase.
Common floor options
| System | What it is | What to check |
|---|---|---|
| Steel joists + panel subfloor | Cold-formed C-section joists with a structural board or panel fixed on top. | Span, deflection and vibration limits; fastener schedule; diaphragm capacity. |
| Joists + topping | As above, with a lightweight concrete or gypsum-based topping. | Added dead load, curing time, sound and fire test reports. |
| Steel deck + concrete | Profiled deck acting as formwork or composite slab. | Support details, shoring, deck rating, stronger diaphragm. |
Four things that drive the choice
- Span and loading: set by the engineer from the occupancy and finishes.
- Vibration and deflection: lightweight floors can feel lively even when strong enough; limits should be explicit.
- Fire and sound ratings: use a tested assembly listing and build it exactly as listed.
- Speed: dry floors go in faster than wet ones, but wet toppings can help sound and diaphragm stiffness.
Buying the joists
When joists are bought as a package, the quote should say section size, thickness, steel grade, coating and whether they arrive pre-assembled. The floor joist procurement questions and floor joists guide give the full list.
Where Digital Oro fits
The catalog lists the pieces of a floor in light steel frame. Digital Oro International lists light steel frame in its material catalog: structural frame in AS1397 G550 AZ150 steel (0.75 or 0.95 mm), available in Australian or American standards, plus wall frames with glass wool, 89 mm x 41 mm pre-assembled floor joists, roof trusses and subfloor systems. See the light steel frame catalog page and the full catalog map. The catalog gives specifications only. It does not give prices, lead times, stock or project references, so none are stated here.
Ask Digital Oro in writing: what span and load each joist section is designed for; which design standard it follows; what coating mass is delivered (the catalog states AZ150) and the mill certificate for it; whether joists arrive pre-assembled; and which subfloor board it recommends with test reports. The catalog mentions 18 mm fiber cement as floor board and an insulated, foldable subfloor, so ask where each is intended to be used.
This guide is general information, not engineering, legal or financial advice. Codes, loads and approvals vary by site; the engineer of record and the local authority decide what your building needs.
Questions people ask
What are the main floor types?
Cold-formed steel joists with a structural panel or board subfloor, joists with a lightweight concrete topping, and composite floors using steel deck with concrete.
Why does the floor matter for sound?
Impact and airborne sound between dwellings depends on the whole assembly: structure, topping, ceiling, insulation and resilient layers, not the joist alone.
Do joists need blocking or bridging?
Usually joist bracing is required by the design standard; the engineer specifies it.
Can the same floor system be used at every level?
Often not; roof, typical floor and podium levels commonly differ.
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.
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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.