Load capacity isn't a single number pulled from a catalog. It depends on several mezzanine floor construction details working together, and getting any one of them wrong compromises the whole structure.

Steel grade and certification matter first. IS certified steel behaves predictably under sustained load, while uncertified steel from an unclear source is a gamble that might not show its true weakness for years.

Deck thickness plays a bigger role than people expect too, and it's one of those mezzanine floor construction details that's easy to underestimate. A thinner gauge might technically hold the intended load, but it can still flex or feel unstable underfoot, which matters a lot if the mezzanine is being used as office or retail space rather than pure storage. Once installed, deck thickness isn't something that gets easily changed, so it needs to be right the first time.

Column spacing and beam sizing come next. Wider spans need heavier beams and more carefully calculated support points. This is precisely why the mezzanine floor fabrication process depends so heavily on proper CAD planning rather than rough on site adjustments made mid build.

Slab capacity underneath matters just as much as anything built above it, and it's one of the mezzanine floor construction details clients ask about most. General guidance across the industry separates load ratings roughly by use, lighter ratings for office or platform use, moderate ratings for general storage and light manufacturing, and much higher ratings for heavy storage or manufacturing environments. Soil condition below the slab affects this too, unstable or sandy ground sometimes needs extra reinforcement before it can safely carry a mezzanine's weight.