High-bay warehouses push slab performance to its limits; taller racking means more weight per point, tighter aisle space, and far less tolerance for floor deviation or deflection. The floor needs to carry static and dynamic loads reliably while supporting narrow aisle trucks, racking legs, and potentially automation rails.
Whether you're working with FM1 slabs or laser-guided trucks, floor specification must be intentional; not generic. This guide covers the critical criteria every high-bay warehouse floor needs to meet for safety, performance, and longevity.
The taller the racking, the more load it transfers to the slab; often concentrated at narrow upright baseplates. Slabs must handle 60–100 kN+ per leg in many high-bay setups. This typically requires a 200–250 mm thick concrete slab with steel mesh or fibre reinforcement, poured on a compacted, uniform sub-base. Use structural concrete (C35 or C40), and avoid using lightweight or marginal mixes. Confirm point load specs with the racking designer and get engineer sign-off.
Very narrow aisle (VNA) trucks require highly consistent floor tolerances to operate safely at height. FM1 or defined movement classes are standard, with flatness deviation limits under 2 mm over 3 m. Laser screeding, controlled pours, and dedicated curing are needed to meet these targets. Specify that flatness will be tested along the racking paths using digital profilographs or defined path measurement tools. Avoid general SR classes; they’re not tight enough for this application.
Floor joints are a major source of damage in high-bay warehouses; especially under forklifts. Wherever possible, use wide-bay or jointless slabs with steel fibre reinforcement to reduce joint frequency. If joints are required, they should be fitted with steel armoured profiles, especially across racking zones and travel paths. Confirm joint layout early in the design to prevent conflicts with upright placement or column pads.
High-bay operations require a hard-wearing surface that resists dusting and wear. A polished concrete finish with densifier treatment is ideal; it improves abrasion resistance, reduces maintenance, and provides excellent reflectivity. If epoxy or polyurethane coatings are used, ensure they meet forklift abrasion standards and are properly slip-rated. Don’t skip surface prep; poor bonding or low-spec sealer will degrade quickly under traffic.
Moisture can affect both coatings and the slab itself. Specify a continuous damp-proof membrane (DPM) below the slab, and confirm moisture content before any finish or racking is installed. Use moisture-tolerant adhesives and avoid installing vapor-sensitive materials until the concrete has cured and tested below 75% RH. Long-term moisture control is critical for preventing delamination and corrosion of racking baseplates.
High-bay slabs often feature defined movement paths for forklifts or AGVs. These paths must be engineered and poured to tighter tolerances than general open areas. Consider applying a higher flatness class (e.g. FM1) in VNA aisles and a lower class elsewhere. This approach balances cost and performance. Coordinate layout early so path-specific tolerances are built into the pour sequence and testing plan.
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