Mezzanine floors: what they are, what they're used for and what to plan first

What is a mezzanine floor?

A mezzanine floor is an intermediate floor built inside a building to create usable space between the ground floor and the roof. In warehouses and industrial units it's usually a steel frame of columns and beams, decked over, with stairs, handrails and a loading point.

Many warehouses have far more height than the ground floor uses. A mezzanine puts a second working level into that height without extending the building.

In most warehouse and industrial settings, a mezzanine is:

• a steel frame of columns, main beams and secondary beams, bolted together on site
• standing on its own base plates on the existing ground-floor slab, usually with few or no connections to the building's walls or frame
• decked with boards, steel or mesh, depending on the use
• edged with handrails and kick plates, with one or more staircases and a gate or opening for loading goods

The official term. In England's fire guidance, Approved Document B, a floor that doesn't extend across the whole building footprint and is open to the floor below is called a gallery. Most free-standing warehouse mezzanines fit that description, and that matters for fire resistance and escape, covered below and in our guide to mezzanine floor building regulations.

What are mezzanine floors used for, and how does the use change the design?

The common uses are storage, order picking, offices, production or workshop space, and retail sales areas. Each one changes the design load, the decking, the number and type of stairs, the fire measures and the approvals, so decide the use before you ask anyone to design or price it.

Tell the designer the use now and in future. A light storage floor can't become a pallet store later without being checked.

Mixed use is common, for example offices along one side and storage on the rest. Each area needs its own design load, marked on the drawings. For storage floors, decide how goods move: pallet gate and forklift, goods lift or conveyor. Each changes the edge design and the layout.

What are the main parts of a mezzanine floor?

A mezzanine floor is made of columns on base plates, main beams spanning between columns, secondary beams carrying the deck, the decking itself, edge protection, stairs and a loading point such as a pallet gate. Each part is designed for the use and load the floor will carry.

Knowing the parts helps you read drawings and compare quotes line by line.

• Columns and base plates. Columns carry the floor to the slab; base plates spread each load onto the concrete. Wider column spacing means fewer obstructions below but deeper, heavier beams.
• Main beams. Span between columns. Their depth eats into headroom below.
• Secondary beams (joists). Lighter, closer sections carrying the decking.
• Decking. Boards, steel plate or open grating and mesh, chosen for load, point loads, wear, sprinklers, light and fire. Ask why the designer chose it.
• Edge protection. Handrails, intermediate rails and kick plates on every open edge people can reach.
• Stairs. Number, width and position depend on how many people use the floor and escape distances.
• Loading points. Pallet gates (swing-over or up-and-over), a goods lift or a conveyor.
• Fire protection, where needed. Fire-resisting ceilings, column casings and fascia panels, depending on use, size and building.

How much weight can a mezzanine floor take?

A mezzanine floor takes whatever it was designed for, and no more. Designers work to a uniformly distributed load in kN/m² for the use, plus point loads from things like shelving feet, machinery and pallet truck wheels. HSE says the safe load and any restrictions should be clearly marked on the floor.

Two numbers matter, and you need both.

• Uniformly distributed load (UDL), in kN/m². The weight the floor carries when spread evenly. The figure for each use comes from the structural loading standard and the designer's assessment.
• Point loads, in kN. Weight on a small area: a shelving foot, a machine leg, a pallet truck wheel. A floor can meet its UDL and still fail locally if the decking isn't designed for point loads.

HSE's warehouse guidance, HSG76, says that where pallet trucks (hand or powered) or other wheeled equipment will be used on a mezzanine, the floor and structure should be designed for three things together: the static load of the stored goods, the wheel loads of the equipment, and the dynamic effects of acceleration and braking. If you think a pallet truck might be used up there one day, say so at the start.

We don't quote typical kN/m² figures here. They're set out in paid structural standards and the right figure depends on your use. Get the design load in writing and check it matches what you'll store.

Working out your own load

1. List what goes on the floor: shelving, stock per shelf, machines.
2. Weigh the heaviest stock, or use delivery paperwork.
3. Note trolleys, cages and pallet trucks with loaded weights, and peak headcount.
4. Ask the designer to state the design UDL and point loads in writing.

What limits where a mezzanine floor can go and how big it can be?

The main limits are clear height (enough headroom above and below once beams are in), where the columns can go without blocking operations, whether the ground-floor slab can carry the column loads, and how the floor affects sprinklers, lighting, heating, doors and fire escape routes.

These are the things that most often change or stop a project. Measure and check them before you ask for designs.

• Clear height. Measure to the lowest obstruction (haunches, lights, sprinkler pipes, heaters), not the eaves. Beams and decking sit in the middle, and both levels need workable headroom.
• Column positions. Columns can land on truck routes, dock doors or packing lines. Mark what must stay clear before design starts.
• The floor slab. Every column load goes into the slab. A thin, cracked or jointed slab may not take it. Ask for a slab assessment as part of the design.
• Sprinklers. A solid deck can block sprinkler coverage below. Talk to your sprinkler contractor and insurer early.
• Lighting and heating. The area below loses roof light and warm air. Plan lighting on both levels.
• Escape routes. The mezzanine can't block existing exits, and its own routes must work.
• Your lease. Many leases need landlord consent for structural alterations.

How do mezzanine pick levels between racking work?

Mezzanine walkways can be built between racking runs so people can pick or replenish at more than one level. HSE says each upper pick location needs a timber or mesh shelf so nobody can fall into the gap when a pallet is removed, and the lower level needs a protective rail so operators can't approach an open edge.

HSG76 describes the typical layout: pallet racking fed by forklift on one side, with people picking by hand on the other, on two or more levels. The particular hazard is the gap left when a pallet is removed. HSG76 says:

• a shelf (timber or mesh) should be provided at each mezzanine-level picking location, so that when there's no pallet in place an operator can't fall into the opening
• a protective rail should be provided at the lower-level picking location so an operator can't approach the open edge

HSG76 also notes that the standard EN 528 may be of use for these systems.

Get one designer to take responsibility for racking, walkways and protection together. The racking still needs the same load notices and inspections as any other racking. See our guides to pallet racking and racking inspection.

Do mezzanine floors need building regulations approval or planning permission?

In England most mezzanine floors are building work under the Building Regulations, so they need approval from building control, mainly for structure, fire safety, escape and access. Planning permission is a separate question: internal works usually aren't development, but in shops adding more than 200 m² of floorspace they are.

This page describes the position in England. Wales, Scotland and Northern Ireland have their own building regulations and planning systems.

Building regulations. The Building Regulations 2010 define building work to include erecting a building and any material alteration affecting structure (Part A), fire escape and spread, or access (Part M). A mezzanine adds loads, people and escape routes, so building control is usually involved. HSE's guidance says mezzanines need careful design to comply, considering the number of people, the use and alternative means of escape in a fire.

Approved Document B says gallery structures should have the fire resistance in its tables, and a gallery over half the area of the space it projects into counts as a storey. That's why some mezzanines need fire-resisting ceilings and casings and others don't. Approved Document K is the guidance on protection from falling, collision and impact.

Planning. Under the Town and Country Planning Act 1990, works that affect only the interior of a building generally aren't development. In England there's an exception: where internal works increase the floor space by more than 200 m² in a building used for the retail sale of goods (other than hot food), they count as development and planning permission is needed. Listed buildings, planning conditions and anything that changes the outside of the building need checking separately.

For full plans versus building notice, completion certificates and what building control looks at, read our guide to mezzanine floor building regulations.

How do you keep people safe at the open edges of a mezzanine?

Under the Work at Height Regulations 2005 employers must prevent falls so far as reasonably practicable. HSE's guidance for mezzanines is to fence every open edge people can reach, provide safe access, guard goods transfer points with something like a swing-over pallet gate, and never rely on chains or tape.

HSE gives transferring stock onto a mezzanine as an example of work at height. The Work at Height Regulations 2005 apply to employers and anyone controlling work at height. Regulation 6 sets the order: avoid work at height where reasonably practicable; otherwise prevent falls; where a risk remains, minimise the distance and consequences. Falling objects count too.

For mezzanines, HSG76 translates that into practical points:

• Fence all openings and edges wherever people have access, to stop people or goods falling, and provide a safe means of access.
• Guard-rail dimensions. New or replacement guard rails should have a top rail at least 950 mm high (existing rails can be 910 mm if fixed before April 2005), gaps between rails of no more than 470 mm, and toe boards suitable to stop people or materials falling.
• Guard the transfer points. Where stock goes on and off the floor, the opening in the fencing needs proper guarding. A swing-over pallet gate can do this: when the gate is open to the forklift side, the operator side is closed.
• No chains or tape. They aren't robust enough to stop someone who stumbles or leans on them.
• Secure the load. Stabilise goods lifted to the mezzanine, for example by shrink-wrapping, so items don't fall onto people below.

What goes wrong

• A gate wedged open to save time, or a section of handrail removed "temporarily" and never refitted.
• Stock stacked against or above the handrail, so it can fall over the edge.
• No kick plates, so small items roll off onto people below.

Put the mezzanine in your risk assessment: who uses the gate, how the forklift driver and deck operator communicate, and who checks the edge protection.

What should you plan before asking for mezzanine floor quotes?

Decide the use and the loads, measure the space and the height to the lowest obstruction, mark what must stay clear below, find out what you know about the floor slab, check sprinklers, lighting and escape routes, and check your lease. Then ask every supplier to price the same specification.

Quotes are only comparable if each supplier is pricing the same thing. Pull this together first.

1. Use and future use. Storage, picking, offices, production or a mix, and any change you expect in the next few years.
2. Loads. What goes on the floor, the heaviest items, any pallet trucks, trolleys or machines, and how many people at peak.
3. Footprint. The area you want and the area you could accept. Columns and stairs take space on both levels.
4. Height. Floor to the lowest obstruction at several points, and the headroom you need below and above.
5. No-go zones. Truck routes, dock doors, fire exits, packing lines, drains and anything that must stay clear of columns.
6. Floor slab. Any drawings, specification or survey of the ground-floor slab. If there's nothing, plan for a slab check.
7. Goods movement. Pallet gate, lift or conveyor, and how often goods move up and down.
8. Fire and services. Sprinklers, alarms, lighting, heating and power on both levels; existing escape routes.
9. Approvals. Who handles building regulations, whether planning applies (retail especially), and landlord consent.

Questions to ask each supplier

• What design UDL and point loads have you used, and why?
• Who provides calculations and drawings for building control?
• Is a slab check included? What if it fails?
• Is fire protection included, and on what basis?
• Are sprinkler, lighting and electrical changes included or excluded?
• What do I get at handover (drawings, load notice, completion certificate)?

For what drives the price and how a quote is built, see our planned guide to mezzanine floor costs; the same approach to comparing quotes is set out in our guide to pallet racking cost.

Related guides

Mezzanine floors: frequently asked questions

Sources

We checked the facts on this page against these sources on 12 November 2026:

• HSE: Warehousing and storage, a guide to health and safety (HSG76)
• The Work at Height Regulations 2005, regulation 6 (legislation.gov.uk)
• HSE: Work at height, the law
• The Building Regulations 2010, regulation 3: meaning of building work (legislation.gov.uk)
• GOV.UK: Fire safety, Approved Document B
• Development Management Procedure (England) Order 2015, article 44 (legislation.gov.uk)

This guide is general information for UK businesses, not legal, structural engineering, building control, fire safety or health and safety advice. Warehouse Racking Hub is an independent guide. We don't design, supply, install or inspect racking or mezzanine floors ourselves. If you ask us to, we'll put you in touch with one storage systems specialist from our partners that covers your area.

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