Mezzanine Floors

Welcome to Technical Topics. The aim with this column is to explore some of the areas that influence the design and effectiveness of a storage system. Technical Topics is a regular feature of Rack It, so, if you have a subject you would like included, let us know.

Mezzanine floor is a phrase that most people recognise as meaning a suspended or supported floor erected within a building having not been part of the original structure. Mezzanine floors are an essential element of most warehouses these days, offering additional work or storage space without adding to the building footprint - something for nothing almost!

This technical topic looks at the venerable mezzanine floor: How they are made, how you access them and what extras are available to improve their performance. But before all that some basic facts; mezzanine floors should comply with BS5950 parts one and five and BS6399. They must also comply with Building Regulations and require approval by your Local Authority building control officer or an approved inspector, and your local fire officer. Any supplier worthy of your contract should handle these approvals for you.

Mezzanine floors have four major structural components, columns, beams, joists and decking. Typically columns are upright posts made of boxed section steel, however, more heavily loaded and multi-tiered floors may benefit from a universal column section design. The standard column design has a squared base plate to spread the floor point loading and a cap plate to support the floor's beams. Columns may also be supported with sway bracing to improve the structures rigidity.

Beams are ‘I’ section steel members that run across the top of the columns sitting on the cap plates. They can be any length and are securely bolted to the columns.

Joists run at right angles to the beams and support the decking surface of the floor. Joists vary in length and rating depending on the use of the floor. They will sit on top of the beams or can be located between the beam webs to reduce the floor's depth.

The decking or floor surface can be either chipboard, open steel grid or solid steel. For particle board applications we use a 38mm thick, tongued and grooved, high-density chipboard, which comes plain or coated in a number of hard wearing finishes including natural, grey, 'flek' or lacquered.

The use of the mezzanine floor will dictate what other features are appropriate. Storage and work space applications would tend to dictate open platforms, office space would usually involve adding partitioning to form an elevated office environment.

For safety reasons, all open platform edges of a mezzanine floor, where people are working, must be protected by a physical barrier. This will normally be handrail around its perimeter which is usually fixed to the side of the floor to maximise the available storage area.

Choose from round, square, solid, tubular, stainless steel, chromium plated or galvanized handrail, depending on your preference or application. You will also require a kick plate around the platform perimeter as an additional safety precaution. Access to the platform for people will generally require a stairway, which will be constructed from steel and conform to the building and fire regulations. We have two standard widths, with non-slip treads and integral handrail.

Access to the platform for goods or product will require some form of lifting device. This may be a conveyor, a goods lift or a forklift truck. In the case of the forklift truck an access gate in the handrail will be required. Called pallet gates these devices ensure that no one can fall though the gate when it is being used to load or unload pallets. Bridges, walkways and cat ladders can be added to your mezzanine to improve access or add functionality. Bridges are popular for navigating conveyor systems, walkways can connect two mezzanine floors within a single building. Cladding can be added to the steelwork to provide fire protection or improve appearance. Up to one hour fire protection is a typical requirement, when deemed necessary.

Mezzanine floors are a cost effective way of increasing floor space by utilising redundant vertical space. Because they are free standing they can be installed quickly with minimum disruption. Both the Unilever Ice Cream and Kelloggs installations in this issue of Rack It feature mezzanine floors. In the case of the Kelloggs warehouse, a new build situation the mezzanine added 570 square metres of floor space.

They might not really be something for nothing, but mezzanine floors do offer a very cost effective way of adding floor space. They might be a far more attractive solution than moving or extending your existing building - if lack of space is an issue for your business.