There are many considerations when designing mezzanine floors, with storage and office mezzanines requiring different approaches to ensure the mezzanine design meets both building regulations and your requirements as a business. Therefore we’ve put together a guide to the different aspects that need to be considered when we design and implement your mezzanine floor solution.
DESIGNING MEZZANINE SPACE
There are a lot of aspects to consider when designing a mezzanine floor solution. We have put together a comprehensive guide to help.
Mezzanine floors are a versatile and bespoke solution that can be designed to create office or storage space within a warehouse facility. However the mezzanine floor itself differs in its design depending on whether it’s being used for office or storage use.
For example a storage mezzanine has quite a lot of deflection, whilst an office mezzanine floor needs to be rigid, so is designed with a deflection of L/360. This ensures that the floor isn’t ‘bouncy’ because this would cause problems, such as cracked plasterboard in your walls and noise when walking around.
It’s also important that a mezzanine is designed with the correct loadings. In most cases an office mezzanine floor is designed with a 3.6kn/m2 capability, which means that the floor can accommodate 360kg per square metre. This is usually more than capable of supporting everyday offices.
When it comes to storage mezzanine floors, they are typically designed to store pallets that weigh 500kg, so essentially this means they can handle a pallet that weighs 500kg every square metre. Storage mezzanines can be designed to handle heavier loads, such as pallets that weigh up to a ton in weight, however we will need to ensure that the concrete slab in the warehouse can take that weight. If not there are options, which we will come to later in the guide.
Mezzanine floors are a bespoke solution and any expert mezzanine designer should be able to design your mezzanine to accommodate whatever facilities you require below the floor. For example if you require office space creating below the mezzanine too, the designer should take into consideration the columns of the mezzanine and hide them within the ground floor office layout.
They should ensure the columns are located either in the corner of rooms or next to building columns. When designed correctly, a mezzanine floor should be inconspicuous and make it hard for anyone to know a mezzanine was the support structure for the office space.
Mezzanine floors can also be designed above existing machinery or areas where employees are working. A site survey will be undertaken to analyse the current space, this is required to be able to adequately design the solution and provide a quotation.
However if the mezzanine is to be installed into an empty warehouse and does not need to accommodate existing machinery or work areas, then it can be designed to a uniform column grid.
This is the most cost effective way of implementing a mezzanine floor solution as the bay sizes can be uniform, meaning the main beams and purlins will all be the same size. This approach reduces manufacturing and installation cost, with the most cost effective column grid sizes being 5000x4000mm or 6000x5000mm.
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WHAT COLUMN GRID SIZES ARE AVAILABLE?
If the mezzanine exceeds the typical size grid (6000x5000mm or any variation of these figures) it’s questionable that the warehouse concrete slab will be able to handle the weight load down the columns.
As mentioned earlier, a mezzanine can be designed to take up to a ton pallet per square metre however changes would need to be made to the concrete floor to accommodate this. The procedure is called ‘piling’ and involves reenforcing the floor with additional concrete to allow it to handle the weight. This can be expensive so it’s often best to design the mezzanine floor to the existing concrete’s capabilities.
Mezzanine floors have been known to be designed with 14000mm spans, which avoids the need for any central columns. However this all depends on whether the columns are an obstruction. It also depends on the weight going on top of the mezzanine. A mezzanine designed to take 300kg per square metre can be designed with a larger column grid than a floor designed to handle 500kg per square metre.
WHAT STAIRCASE OPTIONS ARE THERE?
There are two types of staircases usually designed for a mezzanine floor and which one is chosen tends to come down to the environment it’s to be installed into. If the mezzanine floor is to be situated out in the open within a warehouse, then a standard steel staircase may well be sufficient. These are generally painted black with contrasting nosing’s. These are practical and the most economical option.
However when a staircase is to be installed within an office mezzanine floor design, a higher grade option is more often than not, the desired solution. These are potentially manufactured using stainless steel balustrade and incorporate steel wires or glass.
Office staircases are generally designed to be 1200mm wide, with a dimension on the tread of a minimum of 250mm and a rise of 170mm. Staircases also have a landing after 12 (Sometimes 16) treads. They are required to be designed this way to ensure room to pass on the staircase and to create a resting place (The landings).
CAN I INSTALL A LIFT WITH MY OFFICE MEZZANINE?
The short answer is yes you can, however it may not be cost effective to install one, especially if not required to do so by building regulations.
When it comes to office mezzanine floors, it will be determined at the design stage whether the mezzanine floor requires a lift. This all comes down to disabled access. If there are office areas exclusive to your mezzanine that are not also accessible on the ground floor for wheelchair users, regulations state that you must have a lift (This is applicable to large mezzanine floors and not relevant to small mezzanines with offices).
Ideally the mezzanine will be designed so that there is also office space on the ground floor along with WC and kitchen facilities. This way the facilities are designed to be suitable for everyone and also save money in the process.
If a lift is required there are options available. The most cost effective of which are platform or scissor lifts. A traditional style lift can also be installed, however this would also require a pit creating.
HOW ARE MATERIALS LOADED & UNLOADED FROM A STORAGE MEZZANINE?
There are three ancillaries commonly installed onto storage mezzanine floors to enable clients to populate them; pallet gates, conveyers and goods lifts.
Pallet gates are the most popular option. These create a permanent barrier between the edge of the mezzanine floor and the person operating it. This provides a safe environment to allow them to unload and offload pallets to and from the mezzanine floor.These gates can be designed to suit an array of pallet sizes and are a very cost effective solution.
There are two options available, an up and over design which relies on the operative moving the pallet gate up and down or a pulley design is available for higher pallets. The size of your pallets and products will need to be discovered before a suitable pallet gate can be recommended.
If your storage mezzanine is primarily to be used for picking and packing purposes then gravity fed or automatic conveyer systems are a great way to move stock from the mezzanine. They create an efficient operation as they allow the movement of small components or boxes from the mezzanine floor without the need to load and unload full pallets every time.
Although they can be an expensive solution, goods lifts allow the movement of pallets to and from mezzanine floors, removing the need for a forklift truck. They can be designed to service multiple levels on mezzanines and to handle a range of pallet sizes and weights.
HOW IS A STORAGE MEZZANINE DESIGNED DIFFERENTLY WHEN USED FOR SHELVING?
When a storage mezzanine floor is to be populated with shelving bays, this changes the way it needs to be designed. Generally shelving bays sit on four legs, which in turn creates a point load on the mezzanine.
To ensure that a mezzanine is designed correctly, we would need to know the width and depth of the shelving bays, along with the number of shelf levels and the weight of the products that are to be stored on these shelves.
When designing a storage mezzanine floor that will have shelving storage on it, the shelving layout will be considered and will be designed to ensure the shelving legs sit directly on top of a purlin. If this is not implemented, the shelving can penetrate through the mezzanine decking (Which is 38mm thick chipboard).
WHAT PARTITIONING OPTIONS ARE AVAILABLE FOR AN OFFICE MEZZANINE?
When it comes to designing an office on top or below a mezzanine, there are many partitioning options to choose from. In most cases a stud and track partitioning system will be used. These plasterboard systems are available with a number of different performance characteristics.
What should also be considered within the design is that each different plasterboard system has a varying sound and fire performance.
For meeting rooms, WC and private offices, plasterboards with a high sound performance should be utilised. This is to make sure that conversations don’t travel through the walls. Fire rated boards are used to create fire corridors, dividing walls and staircase enclosures. Whilst plasterboard as standard has a 30 minute fire rating, fire rated boards with their fire protection up to one hour will generally be required.
There are other partitioning systems that are often used in office mezzanine floor design such as glass partitions, which provide an open plan, modern and elegant feel to the facilities. Then there are folding partitions, which are often utilised in between rooms, due to the flexibility they provide. They give the option to open multiple rooms up into one large room at a minutes notice, ideal for boardrooms and meeting rooms.
HOW WE ENSURE THE DESIGN MEETS BUILDING REGULATIONS
How many staircases a mezzanine will require all depends on the size of the mezzanine floor and the distance to a fire escape. To avoid multiple staircases, the positioning of them need to be thought through and considered.
Mezzanine floors up to 20 metres in length can be designed with a single staircase as long as the distance to a fire escape doesn’t exceed the maximum distance stated by building regulations. If the distance is over 40 metres this can potentially be overcome by enclosing the staircase with a fire protected enclosure. These are typically designed from a fire rated stud and track partitioning system.
It may be required to fire rate the mezzanine floor if stated by building control. This depends on a number of factors including the size and use of the mezzanine floor. Fire protection is achieved via the installation of column cases, fascia to the exposed edges of the mezzanine and a suspended ceiling to the underside of the floor.
These materials will protect the mezzanine and in the event of a fire will allow the structure to stand for one hour before any form of collapse. If the mezzanine floor is designed to have people working permanently above or below it, takes up over 50% of the buildings footprint or exceeds 20 metres in one direction, it will generally require fire protection.
ELECTRICS & FIRE ALARMS
To ensure the mezzanine complies with building regulations it will require lighting above and below the mezzanine along with emergency lighting. The emergency lighting will light the exit route in the case of a power failure.
The type of lighting required will all depend on the use of the mezzanine floor. For a storage mezzanine, it will be designed with fluorescent light fittings which will provide a lux level (Brightness) of 200-300 lux.
However within an office mezzanine floor, if employees are to use computers below or above the mezzanine, building control will specify lighting with a higher lux level (400-500lux). This is the minimum brightness requirement for areas with computers.
The mezzanine floor and office space size on the mezzanine in comparison to how large the warehouse is, will determine if the partition wall dividing the office space from the rest of warehouse needs to be fire rated.
If the office space occupies more than 20% of the overall footprint of the building then the dividing wall will need to be fire rated. This includes all fixtures and fittings that may be within the wall such as doors, windows, or glass partitioning modules.
THE THREE KEY ELEMENTS
During this stage, considerations need to be made in regards to how the mezzanine will be constructed. Particularly if the mezzanine is to be situated above any existing production, packing or machinery areas.
The designer will consider multiple solutions whilst designing the mezzanine. They will determine whether the steels can be manoeuvred around the existing equipment or whether the area needs to be cleared before the installation can commence. The designer will put forward a design and solution that causes the least disruption to the clients business.
This is all part of the ‘Principal Designer’ role, which is explained more fully in the next section. Other things that the designer will consider are the availability of plant items on site. Whether additional machinery will need to be hired to assist the construction such as genie lifts, scissor lifts, fork lift trucks and scaffold towers.
As with any construction project, expert project and site management is an absolute must. The project manager will work closely with the designer and will be responsible for the day to day running of the project. They will also design a detailed project plan, which will explain when each aspect of the project is to take place.
The project managers main responsibilities are to work closely with the site manager and ensure that the build goes smoothly, is implemented safely and that the quality of work is maintained throughout.
HEALTH & SAFETY
It’s paramount that the designer of the mezzanine floor solution considers the safety of the installation team. They need to ensure that the mezzanine is implemented safely and they must fully understand how that will happen.
Some of the aspects they will need to consider include knowing where the materials will be delivered to site, how the materials will be moved to the construction area and what segregations are required to ensure the safety of not only the installation team, but also the employees of the client during the build.
There is always the option of installation on a weekend if the disruption caused will be too much when installed during work hours. This will be determined in discussions between the client and chosen contractor.
For any project that involves a mezzanine floor and multiple trades, it is the requirement of the client to appoint a Principal Designer by writing as stated by the HSE (Health and Safety Executive).
This is to ensure that all health and safety issues are considered throughout the design stage. The Principal Designer also ensures that the practicalities of general maintenance after the facilities are built is also considered within the design.
The process of appointing a Principal Designer is a formal one and one that is done via written confirmation (A letter) sent to the chosen company or designer. More information can be found on the responsibilities of a Principal designer here http://www.hse.gov.uk/construction/cdm/2015/principal-designers.htm
Just like a Principal Designer, a client must also appoint a Principal contractor before any work commences on a project involving more than one contractor. The Principal Contractor is responsible for all sub-contractors on site, ensuring their health and safety and making sure that their work is following correct guidelines.
Somebody must be appointed as Principal Contractor, so even if the client intends to use their own sub contractors and manage them, they must appoint themselves as the Principal Contractor and carry out all that it entails including inheriting their responsibilities.
You can find more information regarding the role of Principal Contractors and what that involves here http://www.hse.gov.uk/construction/cdm/2015/principal-contractors.htm