A typical mezzanine design is based around the following.

Footplate - Depending upon load and slab conditions this could be 300 x 300

Column - Typically a box section eg. 100 x 100 SHS but this also depends upon the loading. An outer column can be smaller in size.The most economical grid size is between 3 and 4 metres.

Main beam - A PFC section bolts onto the flange welded to the top of the main columns.

Secondary beam - Usually a C section purlin bolted to the main beam via angle cleats.

Decking - The standard is 38mm moisture resistant particle board but checker plate or open mesh can be used aswell.

Handrails - 50x50 SHS uprights, fixed to the decking, with galvanised tube hand and knee rail. 

Loading:

BS 6399: Part 1 gives dead loads and minimum recommended characteristic imposed loads for floors of office, retail, industrial and warehouses etc. The Code provides uniformly distributed loads per metre height of storage.

For ‘general storage’ the Code recommends a uniformly distributed imposed loading of 2.4kN/m2 per metre of available storage height.

2m of available storage height = 4.8kN/m2

Examples of use; hand pallet truck up to 500kg, shelving with bay loads up to 400kg

3m of available storage height = 7.2kN/m2

Examples of use; hand pallet truck up to 750kg, shelving with bay loads up to 500kg


For offices – general use with partitions = 3.5kN/m2

The list below shows the relationship between column centres and the main beam depth.

4mtr x 4mtr = 254mm beam depth
5mtr x 4mtr = 305mm beam depth
6mtr x 4mtr = 356mm beam depth
10mtr x 6mtr = 533mm beam depth