Mezzanine floor regulations: approval, fire safety and your duties in use

In England and Wales, a mezzanine floor goes to building control before work starts. Fitting one into an existing building is building work when it is a material alteration under regulation 3 of the Building Regulations 2010, and on business premises regulation 12(3) of those Regulations rules out a building notice: a local authority application must be full plans. Internal works need no planning permission in England and Wales, except a retail building gaining more than 200 square metres of floor space or a building whose planning permission restricts its floor space.

Design and approval belong to the installer's engineer and building control. Once the floor is in use, the duties are yours: guarded edges and loading points, a load notice, inspection of the floor and any racking that carries it, and a fire risk assessment reviewed for the new layout.

The Approved Document figures below apply in England. Wales applies the Building Regulations 2010 as amended there, with its own Approved Documents. Scotland requires a building warrant, and Northern Ireland has its own building regulations.

Do mezzanine floors need Building Regulations approval?

Treat the answer as yes. Under regulation 3 of the Building Regulations 2010, an alteration is material if the work "would at any stage result" in the building "not complying with a relevant requirement where previously it did", or in a building already short of one becoming "more unsatisfactory in relation to such a requirement". The relevant requirements include structure (Part A), means of escape (paragraph B1), the structure's stability in a fire (paragraph B3) and access (Part M), and a floor that people work on bears on all four. HSE's warehousing guidance, HSG76, says mezzanines "need to be carefully designed to comply with building regulation requirements", and Approved Document B covers floors "sometimes supported by racking" too.

Regulation 12(3) of the Building Regulations 2010 sets the route. Where the Regulatory Reform (Fire Safety) Order 2005 applies, as it does to a warehouse or shop, a building notice is not an option: an application to the local authority's building control service must be full plans. The alternative is a registered building control approver, who notifies the local authority with an initial notice. A floor fitted without approval can go to the local authority for regularisation if the work was done after 11 November 1985, though you may have to alter it first.

Regulation 11A of the Building Regulations 2010 has required the client in England, since 1 October 2023, to make suitable arrangements for planning, managing and monitoring the project so the work complies, and regulation 11R of the Building Regulations 2010 has placed the same duty on clients in Wales since 1 July 2026. Assembling a mezzanine on site is also construction work under the Construction (Design and Management) Regulations 2015, so your business has CDM client duties as well.

What the Approved Documents say about mezzanine floors

The Approved Documents are statutory guidance, setting out one way to comply. These are the parts a mezzanine touches, as published for England.

Requirement in Schedule 1 to the Building Regulations 2010	Guidance for a mezzanine
A1, loading: dead, imposed and wind loads carried safely to the ground	Structural calculations for the floor, its columns and what they stand on
B1, means of warning and escape	Approved Document B Volume 2, sections 2 to 5, which allow an unprotected stair only where travel distance and numbers are very limited
B3, the structure's stability in a fire	Approved Document B Volume 2, raised storage areas, below
K1 and K2, stairs and protection from falling	Approved Document K, Diagram 3.1: in factories and warehouses (light traffic), 1100mm guarding at landings and edges of floors, 900mm on stairs and ramps. Industrial stairs and ladders to BS 5395-3 or BS 4211
M1, access and use	Approved Document M Volume 2: new ways of getting between levels must comply, and a passenger lift is the most suitable means of vertical access

Part K is outside the list that makes an alteration material, and regulation 4 of the Building Regulations 2010 still requires the new stair and guarding to meet it.

When does a mezzanine floor need fire protection?

In Approved Document B Volume 2, paragraph 7.7 accepts a raised storage floor without the fire resistance Appendix B would otherwise set, if it meets every condition:

• one tier, used for storage only
• few people on it at any one time, none of them members of the public
• open above and below to the room or space it sits in
• means of escape in line with sections 2 to 5
• no more than 10m in width or length, and no more than half the floor area of the space

Automatic fire detection and alarm on the lower level to BS 5839-1 raises the limit to 20m in width or length. Sprinklers throughout the building to Appendix E remove it. Building control and the fire and rescue service may also agree to vary the size, with firefighters' safety in mind.

An office, a floor open to customers or a larger floor falls outside these conditions, and the guidance then looks for the fire resistance in Appendix B. A floor open to the one below is a gallery in Approved Document B, and a gallery covering more than half the space it projects into counts as a storey. Settle with your designer and building control whether a staffed pick floor is "few in number" and still used for storage only.

Do you need planning permission for a mezzanine floor?

In England and Wales, section 55(2)(a) of the Town and Country Planning Act 1990 says works that affect only the interior of a building, or do not materially affect its external appearance, do not count as development, so they need no planning permission.

The exception is retail. Article 44 of the Town and Country Planning (Development Management Procedure) (England) Order 2015 makes internal works development where they add more than 200 square metres of floor space to a building used for the retail sale of goods other than hot food. Wales has the same rule in article 2A of the Town and Country Planning (Development Management Procedure) (Wales) Order 2012. Check this rule before a sales mezzanine goes into a shop or garden centre. Check the conditions on the building's planning permission too, because some cap the floor space or rule out a mezzanine. New windows, doors or an external stair need their own check. In Scotland and Northern Ireland, ask the local planning authority first.

Your duties once the mezzanine floor is in use

The Regulations in this section apply in England, Wales and Scotland, and Northern Ireland has its own equivalents.

Load: mark it and keep within it

Regulation 12(1) of the Workplace (Health, Safety and Welfare) Regulations 1992 requires every floor in a workplace to be suitable for the purpose it is used for, and the Approved Code of Practice, L24, says floors "should not be overloaded". HSG76 asks for mezzanines to be "clearly and conspicuously marked with their safe load-bearing capacity and any restrictions on use". If pallet trucks will run on the floor, it should be designed for their wheel loads and braking and acceleration forces on top of the stock, so take any change in use back to the designer first.

Edges, stairs and loading points

HSG76 says every opening and edge should be fenced where people have access. Four sources give a height:

Source	Status	Guard rail height
Approved Document K, Diagram 3.1	Statutory guidance, England	1100mm at landings and edges of floors in factories and warehouses (light traffic), 900mm on stairs
Schedule 2 to the Work at Height Regulations 2005	Law, with fixed figures for construction work only	Highest guard-rail at least 950mm, or 910mm if fixed before the Regulations came into force, gaps no more than 470mm
HSE's work at height FAQs	Guidance outside construction	No prescribed dimensions. 950mm minimum in HSE's operational guidance, and 1100mm Building Regulations guarding treated as sufficient for warehouses
Paragraph 580 of HSG76	Warehouse guidance	New rails at least 950mm, existing ones 910mm if fixed before April 2005, gaps no more than 470mm, suitable toe boards

On height, 1100mm at the edge of the floor meets all four. Regulation 12(5) of the Workplace (Health, Safety and Welfare) Regulations 1992 adds handrails on staircases.

The loading point is the one place the edge has to open. Schedule 2 to the Work at Height Regulations 2005 allows edge protection to come off only for the time and to the extent the task needs, with effective compensatory measures while it is off. HSG76 gives a swing-over pallet gate as one way to guard the transfer point, and says chains and tape should not be used as edge protection.

Under regulation 12 of the Work at Height Regulations 2005, guard rails and gates whose safety depends on how they were installed are inspected in position before use. Where they are exposed to conditions causing deterioration liable to result in dangerous situations, they are also inspected at suitable intervals and after exceptional circumstances, such as a lift truck strike. Record each inspection. Our work at height guide covers the rest of the Regulations.

Goods lifts and the fire risk assessment

A goods lift serving the floor is lifting equipment. Regulation 9 of the Lifting Operations and Lifting Equipment Regulations 1998 requires a thorough examination before first use where its safety depends on the installation, then, where it is exposed to conditions causing deterioration, at least every 12 months, or every 6 months if it lifts people, unless an examination scheme sets the intervals, and after exceptional circumstances such as an impact. Our LOLER guide covers who examines and what the report contains.

A new floor changes escape routes and where people work. In England and Wales, article 9 of the Regulatory Reform (Fire Safety) Order 2005 requires the responsible person to review the fire risk assessment after "significant changes, extensions, or conversions" to the premises, and to record the review. Scotland and Northern Ireland have their own fire safety law.

Rack-supported mezzanines and racking inspection

Some floors are carried by the racking. HSG76 describes pick floors between racking runs, with lift trucks replenishing one side and pickers working the other, and asks for a timber or mesh shelf at each mezzanine picking location, so nobody falls into the gap a removed pallet leaves, and a protective rail at the lower picking level.

The racking carries the floor and the people on it. HSE gives storage racking as an example of work equipment that needs a safe working load marking. Regulations 5 and 6 of the Provision and Use of Work Equipment Regulations 1998 require it to be maintained in an efficient state, in efficient working order and in good repair, inspected after installation where its safety depends on the installation conditions, and inspected at suitable intervals where it is exposed to conditions causing deterioration liable to result in dangerous situations. HSG76 sets out the regime:

• a nominated person responsible for racking safety decides the inspection frequency
• anyone who sees damage reports it straight away
• visual inspections run weekly or at other regular intervals based on risk assessment, with a written record
• a technically competent person carries out an expert inspection at intervals of not more than 12 months and reports in writing

Damage is graded green, amber or red. Amber needs remedial work as soon as possible, a damaged component stays empty once unloaded, and amber becomes red after four weeks without repair. Red means offload the area at once and isolate it until repaired. HSG76 points to the Storage Equipment Manufacturers' Association (SEMA), an industry body, for the detail. SEMA's documents are industry guidance, and the legal duty sits in PUWER.

A strike nobody reports waits for the next walk round, so make reporting quick and free of blame for the driver. Racking is one of the four places an Opus assessment of a warehouse starts, and our warehouse and logistics health and safety support covers it.

A mezzanine floor checklist for operators

Before you order

• Write down what the floor is for and what will run on it, pallet trucks included, because that sets the design and the fire guidance.
• Agree who makes the building control application, and check the 200 square metre retail rule in England and Wales if the building sells goods.
• Give the installer the building information they need, such as the slab, sprinklers, detection, services and any asbestos register, and plan the work around live operations.
• Design in the loading point, the pallet gate, the stair and its handrails.

At handover

• File the completion certificate with the drawings and calculations. L24 says to obtain information on design limits and safe loading when you take possession of the work.
• Put up the load notice, and have the guard rails, gates, stairs and any supporting racking inspected and the goods lift examined before first use.
• Review and record the fire risk assessment.

In use

• Keep loads within the notice, and the pallet gate closed on the edge side except while loading.
• Report every strike on a rail, gate or upright the same shift, and inspect after it.
• Keep racking inspections and the goods lift's examinations in date.

Frequently asked questions

Do mezzanine floors need building regulations approval? Assume so in England and Wales. Fitting one is a material alteration under regulation 3 of the Building Regulations 2010 if the work would at any stage leave the building short of a relevant requirement, such as structure, means of escape or access, where it previously complied. Where the Regulatory Reform (Fire Safety) Order 2005 applies, as it does to business premises, an application to the local authority must be full plans.

Do you need planning permission for a mezzanine floor? In England and Wales, internal works need none, unless the building is used for the retail sale of goods other than hot food and the floor adds more than 200 square metres, or the works materially change its external appearance. In Scotland and Northern Ireland, ask the local planning authority.

What is the minimum height for mezzanine floor guarding? 1100mm at the edge of the floor in a factory or warehouse in England, under Diagram 3.1 of Approved Document K, and 900mm on the stair. HSE's guidance gives 950mm as a minimum, so 1100mm meets both.

Do mezzanine floors need fire protection? It depends on use and size. In England, Approved Document B Volume 2 accepts a single-tier storage floor without fire-resisting structure if it meets five conditions, including few people, none of them public, and no more than 10m in width or length and half the area of the space. Detection below raises the limit to 20m, and sprinklers throughout remove it.

How often should a mezzanine floor be inspected? No law sets one interval. Under regulation 12 of the Work at Height Regulations 2005, guard rails and gates whose safety depends on their installation are inspected in position before use, and those exposed to deterioration at suitable intervals and after exceptional circumstances such as a strike. For racking under the floor, HSE's guidance is visual checks weekly or at risk-based intervals and an expert inspection at least every 12 months.

Where to start

Start with three documents: the completion certificate, the design load, and the last inspection report for the guard rails and any racking under the floor. A missing one is your first job. A named Opus consultant can walk the floor with you and give you a priority-ranked list of what to fix.