Precast Floor Slabs

Structure

Hollow-Core Slab Sizes

DepthWeightSpanUse
150 mm (6")~220 kg/m²≤6 mMezzanines, corridors
200 mm (8")~280 kg/m²≤9 mClassrooms, offices
250 mm (10")~340 kg/m²≤11 mSanctuaries
305 mm (12")~400 kg/m²≤14 mLong-span sanctuaries
355 mm (14")~460 kg/m²≤16 mHeavy / very long span

Standard width: 1220 mm (4'). Prestressing strands: 12.7 mm (1/2") dia.

Minimum Bearing Lengths

Support TypeMin.Recommended
CMU / grouted masonry65 mm75–90 mm
Cast-in-place concrete beam75 mm90–100 mm
Steel beam (bearing plate)50 mm75 mm
Precast beam / inverted tee75 mm90 mm

Bearing Pads

Keyway Grouting

ParameterRequirement
Grout typeNon-shrink cementitious, 30 MPa min.
Keyway gap15–25 mm between slabs
Placement temp.10°C–30°C
Pre-wet surfacesSSD (saturated surface dry)
Cure timeMin. 24 hrs moist cure
Core fill depth300–600 mm at bearing ends

Rod every metre of keyway. Dam perimeter ends with foam backer rod before grouting.

Self-Levelling Topping

ItemValue
Typical thickness~25 mm
Walkable4–6 hours
Ready for flooring24–48 hours
Gauge pin spacing1200–1500 mm centres
Temp. range10°C–30°C

Erection & Rigging

Code References

Safety — Do Not Forget

Pro Tips