Spanworks › Steel warehouse buildings

Steel warehouse buildings

A warehouse is about clear height and clear floor. A steel portal frame gives spans of 20 to 40 m with no internal columns, so racking and forklifts can use the whole floor.

Choosing the eaves height

Work up from what you will store. Take the top of your highest racking beam, add the load, then allow clearance for sprinklers or lights and the depth of the frame haunch. As a rough guide:

Spans and frame spacing

Most warehouse frames span 18 to 36 m at 6 to 7.5 m centres. Wider spans need deeper rafters, so for very wide buildings a two-span frame with a central valley can be cheaper. Low pitches of 4° to 6° keep the roof volume down.

Loading doors

Allow about 3.5 m wide by 4.5 m high for a forklift door, and 4 to 5 m wide by 5 m high for lorries. Insulated roller doors are needed in a heated building (U-value 1.3 W/m²K under Part L 2021).

Fire safety

Approved Document B allows up to 45 m of travel to an exit where there are alternative routes, and 25 m where there is only one. Large storage buildings may need compartment walls or sprinklers, and buildings close to a boundary may need fire-resisting walls on that side.