When designing a mezzanine floor for storage use, it’s important to consider a number of aspects. From the weight of the products being stored on top, to the way in which the client intends to get products onto the mezzanine. Therefore we’ve put together a guide covering the different aspects to consider when you require a storage mezzanine floor.
Typically mezzanine floors for storage are designed to either accommodate additional shelving for small parts storage, or designed to accommodate additional pallet storage.
This allows companies to relocate inventory that is taking up valuable floor space and store it in the ‘air’ allowing their company to free up valuable floor space to increase production and allow business expansion.
If you plan on utilising your mezzanine floor for pallet storage the following information needs to be answered prior to the design of the mezzanine floor.
Typical pallet configurations are a standard cheap pallet measuring 1200x1000mm or a Euro pallet measuring 1200x800mm. If the product that is to be stored on the pallet has an overhang this also needs to be considered.
To design the mezzanine floor we also need to know the height of the pallet with the product. This will allow us to specify the correct pallet gate for the loading and unloading of materials.
Mezzanine floors are typically designed to store pallets that weigh 500kg, which essentially means you can store a pallet weighing 500kg every square metre on the mezzanine floor.
Mezzanine floors can also be designed to accommodate heavier pallets, up to a ton in weight, however considerations will need to be made with relation to the warehouse concrete slab to see if it is capable of taking the weight.
If the mezzanine floor is to be designed for additional shelving, it changes the way the mezzanine floor is designed. A shelving bay typically sits on four legs which creates a point load on the mezzanine.
In order to ensure the mezzanine is designed to take the weight of the shelving bay we need to know the width and depth of the shelving bay along with the number of shelf levels and the weight of the product that is to be stored on each shelf level.
When designing a mezzanine floor for shelving we would incorporate the shelving layout into the design of the floor itself ensuring that the legs of the shelving sits directly onto a purlin. If this is not the case, the shelving can penetrate through the mezzanine decking (which is 38mm thick chipboard)
Mezzanine floors are constructed from four main components. Main steels, purlins, columns and decking. In order to design the optimum column layout (the least amount of columns) its important to understand what is happening underneath the mezzanine floor.
If the floor is to be designed over an existing warehouse layout, the column layout would vary when compared to if the floor was going into an empty warehouse. The column grid for this solution is a ‘bespoke’ solution and is designed on a project by project basis.
A survey of the existing footprint will be undertaken and then the floor will be designed around the footprint. The good news is mezzanine floors can be very flexible and columns can be hidden in and around the existing layout. Because these solutions are bespoke a site survey is required to provide a quotation. This type of floor is typically more expensive than a floor with a standard column grid, although still offering outstanding value for money.
If the mezzanine floor is to be installed into a new warehouse and does not need to be designed to accommodate machinery, shelving or production lines, it can be designed with a uniform column grid.
This is the most cost effective way of designing a mezzanine floor as the bay sizes can be uniform, which means all the Main beams and purlins will be the same size. This reduces manufacturing and installation cost as all the components are the same size and the area is clear for installation. The most cost effective column grid sizes are 5000x4000mm or 6000mmx5000mm.
Typically mezzanine floor grids are designed within a 6000x5000mm configuration (or a variation within these figures). If you exceed this size grid it can be questionable that the warehouse concrete slab would be capable of taking the load down the columns.
If the floor isn’t adequate, this can be overcome by ‘piling’ the existing concrete floor, which means re-enforcing the floor to take the load with additional concrete. This can be expensive so its best to try and design the floor within the warehouse floors capabilities.
However mezzanine floors have been designed with 14000mm spans, avoiding the need for any central columns. It all depends on if the columns are an obstruction. Items that can affect the column grid size are the imposed loading on top of the floor. A mezzanine floor designed to take 300kg per square metre can be designed with a larger column grid than a floor with 500kg per square metre.
Pallet Gate. The most popular option. A pallet gate is a solution that creates a permanent edge between the operative and the edge of the mezzanine floor making it ultra safe to unload/offload pallets.
The pallet gates can be designed to suit a range of pallet sizes and are a very cost effective solution. Pallet gates can be an up and over style which relies on the operative manual moving the pallet gate up and down or a pulley style pallet gate is available which is suitable for higher pallets.
Conveyors. Gravity fed conveyors or automatic conveyors are a great way to move stock from a mezzanine floor particularly if you are planning to use your mezzanine floor for picking and packing purposes.
They allow movement of small components or boxes from the mezzanine floor without having to load full pallets at a time and allow for a nimble operation.
Lifts. Goods lifts, although an expensive solution allow the movement of pallets to and from the mezzanine floor without the need of a fork lift truck. They can be designed to access multiple levels on the mezzanine floor and can be designed to accommodate a range of pallet sizes and weights.
Staircases. The size of the mezzanine floor and the distance to a fire escape will determine how many staircases a mezzanine floor will require. When designing a mezzanine floor the position of the staircase needs to be thought through to avoid multiple staircases.
A mezzanine floor up to 20 metres in length can be designed with a single staircase depending on the distance to the fire escape. If the distance is over 40 metres this can potentially be overcome by enclosing the staircase with a fire enclosure, typically designed from a stud and track partitioning system which offers the fire protection required.
Fire Protection. Depending on the size, use or circumstance of the mezzanine design, it may be a requirement of building control to fire rate the mezzanine floor. This is achieved by installing column cases, fascia to the exposed edges and a suspended ceiling to the underside of the floor.
These materials will protect the mezzanine steel for a one hour period and in the event of the fire would allow the structure to stand for an hour before any form of collapse.
If the mezzanine takes over 50% of the building, exceeds 20 metres in one direction, or is designed for people to work permanently below or above, the mezzanine floor will generally require fire protection.
Electrics & Fire Alarm. To comply with building regulations the mezzanine floor will require lighting below and above the mezzanine floor complete with emergency lighting. The emergency lighting will in the case of a power failure highlight a way of escape via the fire exit.
The type of lighting required will depend on whats happening below or above the mezzanine floor. For general storage purposes the mezzanine floor will be designed with fluorescent light fittings providing a lux (brightness level) of 200-300lux.
If people are to use computers below or above the mezzanine floor, building control will specify a higher lux (400-500lux) which is the minimum requirement for brightness when people are using a computer. The general fitting used is an LED panel system which fits into the suspended ceiling grid (see notes above on fire rating).
Design Stage. During the design process, consideration needs to be made about how the mezzanine floor will be constructed, particularly if the mezzanine floor is to be installed above existing production, machine or packing areas.
Can the steels be manoeuvred in an around the existing equipment? Or would the area need to be cleared prior to the install? When designing the floor the designer will consider all these aspects and will put forward a design and solution that allows the mezzanine floor to be installed with the least disruption to the business.
This is part of the ‘Principal Designer’ role which is explained in the section below under ‘important considerations’. Other items to consider are what plant items are available on site and if additional machinery will need to be hired to assist the mezzanine build. Typical plant requirements are scissor lifts, genie lifts, fork lift trucks and scaffold towers.
The Build. With any construction project, expert project management and site management is a must. Working closely with the designer the project manager will be responsible for the day to day running of the project and will design a detailed project plan with key milestones of the build.
Working closely with the site manager, the project manager is in place to ensure a smooth, safe build takes place and also ensure quality of work is maintained throughout the works.
Health and Safety. Paramount to the design stage is understanding how the mezzanine floor will be implemented into the building in a safe manner. Understanding where materials will be delivered, the impact of moving materials to the required work area and what segregations are required to keep the installers and companies employees safe throughout the process.
If installing within a busy working environment the mezzanine floor can often be installed out of hours to prevent disruption to your workforce.
Principal Designer. When designing a mezzanine floor it is important to understand the roles and responsibilities of both the client and contractor from a health and safety perspective.
On a construction project that involves multiple trades (mezzanine, electrics, fire alarm, shelving etc) the client is required by the HSE (Health and Safety Executive) to appoint a ‘Principal Designer’ to ensure all the considerations highlighted within this document are covered.
This is a formal process in which the client formally appoints (by letter) a company or designer to design a solution that is fit for purpose and meets all the requirements from a health and safety perspective.
More information can be found regarding the role of principle designer on the HSE website here: http://www.hse.gov.uk/construction/cdm/2015/principal-designers.htm
Principal Contractor. For any project that involves more than one contractor it is important that the client (end user) appoints a Principal Contractor to again meet the requirements set out by the HSE.
The Principal Designer is responsible for the health and safety for all contractors on site and again must be formally appointed by the client. More information is available on the HSE website regarding the role and responsibilities of a Principal Contractor http://www.hse.gov.uk/construction/cdm/2015/principal-contractors.htm
The role of principle designer and contractor is an integral part of the design of a mezzanine floor project and is a key part of the mezzanine floor design process. For more advise with how to implement a mezzanine floor into your business please contact Nexus Workspace where we have extensive experience delivering mezzanine floor based solutions into a range of businesses throughout the north of England.