Comprehensive engineering guide for composite floor deck profiles (38/151 and 60/940): unpropped span limits, shear stud spacing, concrete slab thickness, and structural load tables.
In multi-storey steel construction, mezzanine platforms, and logistics buildings, composite floor decking represents the most advanced slab method—eliminating timber shuttering, shortening construction timelines, and significantly increasing seismic performance. Acting as both formwork during concrete pour and external tensile reinforcement once cured, structural composite decks lock mechanically with concrete via embossed ribs.
1. Composite Slab Mechanics & Embossment Interlock
Standard roof profiles cannot be deployed as structural floor decks because smooth sheets lack shear bond with cured concrete. Composite decking sheets feature precision-engineered surface indentations (embossments) along web ribs. Upon concrete curing, these embossments develop comprehensive mechanical interlocking that resists longitudinal shear stress, acting as full tensile bottom reinforcement.
2. 38/151 Profile: Slim Slabs & Mezzanine Floors
The 38/151 profile features a 38mm rib depth, 151mm pitch, and 900mm effective cover width. Ideal for secondary beam spans between 1.80m and 2.40m, it minimizes total slab depth (typically 100mm to 120mm) and dead weight in mezzanine or office levels.
3. 60/940 Profile: Wide Unpropped Spans & Heavy Loads
Featuring a 60mm deep trapezoidal profile and robust sectional modulus, the 60/940 deck spans up to 3.50m to 3.80m without temporary propping. It is the premier choice for manufacturing floors, logistics hubs, and commercial centers carrying heavy live loads.
Comprehensive Engineering Comparison Matrix
| Specification Parameter | 38/151 Composite Deck | 60/940 Composite Deck |
|---|---|---|
| Rib Height | 38 mm | 60 mm |
| Gauge Range | 0.70 mm to 1.20 mm | 0.80 mm to 1.50 mm |
| Unpropped Span Limit | 2.00 – 2.40 m | 3.20 – 3.80 m |
| Min. Slab Thickness | 100 mm | 120 – 150 mm |
| Concrete Volume (m³/m²) | ~0.075 m³/m² | ~0.098 m³/m² |
Verdict: Specify 38/151 where floor-to-ceiling clearance is constrained and secondary beams are closely spaced (<2.20m). Select 60/940 for open industrial spans up to 3.50m requiring unpropped construction and high load capacities.
Calculate Live with Your Project Dimensions
Apply the engineering criteria from this guide to your specific building; estimate take-offs, load capacities, and logistics instantly.
Galvanized C / Z / Sigma Purlin Span & Deflection Calculator
Specify your purlin span between trusses, purlin spacing and profile section to calculate deflection limits (L/200, L/300), safe capacity, and required steel tonnage per EN 1993-1-3.
Z200 / 2.00 mm (L = 6.00 m)
Frequently Asked Questions
What minimum galvanizing coating is required for composite deck sheets? ▼
EN 10346 specifies a minimum Z275 g/m² zinc mass to ensure structural corrosion protection on the exposed slab underside.