Mezzanine Construction – 9 Things You Should Know
A mezzanine is a good investment. A mezzanine floor is a very easy way to create extra, very low cost productive space. Constructing your mezzanine should be very straight forward in engineering terms, however there are varying opinions on design. People with vested interests in wanting to deal with your project, often as part of other works that they may be doing at the time, can easily persuade you to embark on a course which falls well short of your expectations. You should not be derailed by this, there are certain fundamentals that if deployed will ensure you don’t fall into the trap of going with popular opinion which is not the same as expert advice.
There are over 40 combinations and facilitations a mezzanine can bring to your business and they can be expensive in the wrong hands causing delays and unnecessary frustrations. A mezzanine floor should provide flexible, low cost productive business space and armed with these eight fundamentals your mezzanine construction is much more likely to maximise its contribution. My fastest payback time for a mezzanine floor construction project was under 3 months. These are the eight useful things to know to achieve rapid pay back results.
First Thing to know: Why would I want a Mezzanine? A mezzanine makes great people space so, showrooms, retail, restaurant, office, storage, production, workshop, exhibitions, museums, schools, libraries, gymnasiums and leisure are all good working examples. They are an easy retro fit and can be taken down again with relative ease making them good for landlord, tenant and private ownership as an obvious choice for developing temporary or permanent space provision. Landlords frequently will provide these facilities incentivising the cost into the lease.
Second thing to know: Is there potential and what will a Mezzanine cost? Once you are in your building, warehouse or factory unit or even shopping mall or out of town location, if nobody has occupied it before you, then you will have perhaps some basic hospitality plumbed in and some services and a lot of floor space. Here in the UK it is common place for architects and property developers to use steel frameworks because they can go higher more economically. In warehouses the construction is often a series of frames called portal frames onto which cladding rails and the building skin is fixed. If your property is not already divided up for you then you will be staring up at rafters and in a portal frame building you should have up to 6m at the eave and a meter or more additional height at the apex in the middle. If you look up at the eave rafter at the side of the building inside you will see a funny little triangular bracket between the rafter and the column – we call this the haunch and it is generally about 5m plus to the underside.
Anything over 5m is good, under 5m you will need professional help. If you are building this structure make sure you have at least 6m to this point and then you can install a mezzanine floor if you ever want one completely unrestricted by the haunch. There are many reasons for not building to this height, but low level production units won’t work as warehouses later so unless you really can’t afford it go higher, use the height, because you will add value through broader appeal than if you stay low. Anyway all that said, why it is free space is because you have bought or rented the floor space so the headroom is technically free in property terms. Mezzanine floors have a price spread of £90 to £250 per square meter, less than half of the new build price so it is relatively cheap to develop. Not only that unless it is more than about half to two thirds of the total floor area it may be exempt from council tax, particularly if it is a removable structure as it is regarded as an item of plant. So read on…
Third thing to know: Do I need planing permission for a Mezzanine? No, you do not need planning consent, unless you are altering the outside appearance of your building with windows for example, but you do need building regulations in England and Wales and a warrant in Scotland and this is what you need to know about them:
- You need proof that the supporting concrete floor is structurally up to the imposed loadings.
- You need to have a designated approved route off the floor and out of the building to satisfy fire regulations.
- You need to ensure the floor can withstand fire for up to an hour if people are working on it.
- You need drawings of the proposed works.
- You need a block plan and a site plan.
- You must provide structural calculations demonstrating the steel work and decking will take the design loads.
There are a few other items which arise out of this, but these are the main ones. In England and Wales you can proceed ahead of the building regulations, but be warned that if during this statutory process changes are ordered it may result in expensive re-work for which you will be charged. In Scotland you need the warrant first and any qualified structural engineer can sign off the warrant. If you are at the design phase you will need to ensure that foundations are provided for any floor supporting columns, these go down before the floor is poured. If you don’t have this facility you will need to check the ground can take the weight without your floor cracking up.
The fourth thing to know: How long will it all take to construct a Mezzanine? Well, if there are no hiccups from receipt of approvals 2 to 4 weeks for little floors 8 to 12 weeks for floors up to football pitch size and somewhere in between for the rest. Planning will take 6 weeks if you know what you are doing, longer if you don’t and building regulations 2 to 3 weeks if you use an agent, 6 weeks if you don’t. Add design and planning time in for yourself and getting in prices etc. If you have weak ground you may have to add 6 weeks for design and 6 weeks for ground works, so don’t start winding up your supporting teams about deadlines. It takes 28 days for concrete to reach specific hardness no matter how much pressure you are under, unless you add expensive resins and this is not always advisable. Additionally, there will be sampling and design work to do so allow plenty of time for orderly progress and a job well done. Even with all this it will still be an economical solution for you.
The fifth thing to know: Who should I buy it from? There are specialists. You can have a concrete mezzanine put in at the design phase, they can be quieter, better for wet processes or plant rooms and span larger spaces but they usually cost a lot more. For the heavy stuff or special design spans the contractor may have a good solution. I would avoid contractors for all retro-fits and go instead to specialists. I would also encourage you to thoroughly investigate the benefits of having the mezzanine separate from the main shell, 9 times out of 10 it will serve you better. Buy them from storage specialists or better still materials handling engineers then you will get help with all the other aspects too.
The sixth thing to know: Should I buy second hand? The chipboard decking rarely comes up well when dismantling the floor. There are minimally three construction methods and several material specifications, all doing different jobs. Once materials are orphaned from the main build even the experts have trouble with them. Hot rolled sections are designed to a span to take specific loadings with specific properties. I have yet to meet anyone who bought a second hand floor able to account for this information or who knows whether or not their construction is a 360, 250, or centre build design, what the service or dead load is, or provide any structural calculations for the floor other than very rarely the original calculations which were provided case specific for that application and not the current application all after it had obviously stood in someone’s yard for six months.
If you move a floor you need the manufacturer to re-approve the calculations and issue a certificate of verification. You are highly unlikely to find a second hand floor in the possession of someone qualified to provide this support. I have found people actually pay more for used floors than new ones. It costs about 25% of the cost of a new floor to take it down and pack it correctly for dry storage, properly inspected and labeled up. It costs the same to re-install it. You will spend a further 30% to 40% with a reputable salvage company re-assembling the specification for your application including correct structural information. Unless you are prepared to do the work yourself and know the location and history of the floor and put it back up identically to the way it came down, avoid it. The only real value is scrap or architectural salvage for re-use by experts.
The seventh thing to know: How can I tell I am being sold a new mezzanine and not a used one? Yes, I am afraid this does happen. All you can do is take up references, ask about the issues raised above and always obtain 3 quotes, remembering if something is too good to be true it probably is just that. If you are in doubt, you can’t hide marks and damaged materials and don’t part with any money until you have all the correct technical information for the authorities.
The eighth thing you need to know: How do I know if my mezzanine design is right? Often the floor will be made to suit an application, this can range from packing materials through to a night club. Whatever it is, if you are assisted by a materials handling engineer then plans will have been drawn up illustrating the activities with specific loading information detailed to be accommodated at the production phase of the project. Specifically this will include:
- Finishing details of the decking to adjoining structures with no gaps
- Floor supports and hot rolled sections sympathetically and regularly spaced
- Deflection ratings assessed for you for the application (you don’t want it to feel like a trampoline)
- Methods of feeding goods, services and facilities required on or off or to and from the floor
- A full access statement and provision for personal welfare on the floor
- The finished floor height and any structural technicalities taken care of for you
- Finishing details for doors, carpets or special surfaces aligned to existing structures
There are many other things as well, it all comes under the heading of attention to detail.
The ninth thing to know: What sort of equipment should I consider to go with a mezzanine? The easiest answer is a list of equipment commonly supplied with mezzanine applications:
- Steel, stainless steel and timber and steel staircases
- Steel fire escapes
- Cat ladders
- Goods lifts
- Wheelchair lifts
- Lifting tables
- Storage systems including racking
- Pallet loading gates
- Mobile pallet stackers with electric lifts (cheaper than lifts)
- Fire retardant materials
Some more storage ideas These 9 guides will help you decide how you want to proceed with your new mezzanine floor project, but there are alternative ways to use headroom, for example raised storage platforms for bulkier items which can’t be conveniently stored in shelving or pallet racking. Two tier systems are alternatives too, you can use pallet racking or shelving sections to construct storage space and flooring into the headroom of your building.
If you decide to embark on a mezzanine floor project and you contact prospective suppliers they should be prepared to come and see you to take information on the application, take an interest in any additional equipment you may need to complete the application and offer to help with regulations and technical issues.
Many may be reluctant to assist with the civil engineering aspects preferring that you make your own arrangements. You should be wary of anyone unable to help with structural calculations. This is essential and may indicate that your supplier is not qualified in the technical competencies required to complete the work.
In cases where such doubt arises you might wish to involve a structural engineer to oversee the work or obtain further quotations.
You can find more information from http://www.engineeredsolutions.info under the mezzanine floors tab, there are buttons at the base of the home page where you can find more engineering project and design support if you need it.