Mezzanine Load Ratings Explained
What PSF actually means, how span and decking affect it, and what code requires.
Every steel mezzanine quote references a load rating in PSF, but most people asking for a quote have never had a reason to know what that number actually means. Here's a plain-English breakdown of load ratings, what drives them, and how to know what you actually need.
What PSF Means
PSF stands for pounds per square foot — the amount of load a mezzanine's decking and structure are engineered to safely carry across every square foot of the platform, whether that's people, furniture, storage bins, or a parked vehicle. DOM Contracting's standard load rating is 150+ PSF, which covers general storage, foot traffic, and most vehicle applications. Structures can be engineered with additional reinforcement beyond that standard for heavier vehicles, dense storage, or specialized equipment.
How Span Width Affects Load Rating
A longer span between supports requires heavier, deeper beams to hold the same PSF rating, because the beam has to resist more bending force across the distance without excessive deflection. This is the core tradeoff behind clear-span vs. center-column construction: a clear-span mezzanine can hit any span width, but cost rises faster as the span grows, while adding a center column lets a wide platform hit the same load rating more economically.
Decking Material and Load Capacity
The decking surface itself is engineered together with the structural steel to meet the overall PSF rating. Bar grate is economical and good for ventilation, B-decking with laminate gives a solid industrial-grade surface, composite decking and plywood with finished flooring suit loft workspaces and living space, and concrete-filled metal decking is reserved for maximum load-capacity applications. See our cost factor guide for how decking choice affects overall project price.
Code Requirements & Engineering
Every DOM Contracting mezzanine includes PE-stamped structural engineering drawings sized to the specific load rating your project needs, plus full local permitting. Building code sets minimum requirements for railings, egress, and structural safety factors on top of the raw PSF number — which is why an accurate load rating has to come from an actual site evaluation, not a generic online chart.
Not Sure What Load Rating You Need?
Tell us what you're planning to store or park on the mezzanine — including anything unusual, like a four-post car lift — and we'll confirm the right PSF rating and give you a free, no-obligation estimate.
Common Questions
Get an Accurate Load Rating for Your Project
Free, no-obligation consultation — we'll confirm the right PSF for your space.