Mezzanine Floor Definition | Mezzanine

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Mezzanine Floor Definition

Mezzanine Floor Definition

Mezzanine Floor Definition. What is a  Mezzanine

Mezzanine floor tiers (mezzanine levels ) are built within an industrial building, between the ground floor and the eaves of the warehouse. A Mezzanine floor is essentially a raised platform floor, which will provide additional usable space in the buildings volume, to its maximum potential for many applications, including storage and offices. Industrial buildings have at least six metre headroom and can easily accommodate pallet racking or mezzanine floor levels. The ground floor slab in modern industrial facilities are specifically designed to withstand substantial heavy static and dynamic loading’s from fork lift trucks etc and therefore can readily support the imposed loading’s from a mezzanine floor installation. However for excessive loading requirements ( two or three tier mezzanines for example ) it is recommended that a specialist company undertake a core investigation ( core sample ) to ascertain the composition and strength of the slab and the sub soil.

Mezzanine and the benefits to businesses.

Mezzanines ( mezzanine floors and flooring ) can extend to the full limits of the industrial building, from its ground floor footprint to the full limits of the buildings volume. In contrast a mezzanine floor platform can also be, only a small percentage of the building. A mezzanine can be just a small storage area or office platform, taking up less than 50% of the industrial building. In these instances, mezzanine floors are not subject to fire protection, unless used for offices or retail purposes. Single tier mezzanine structures can be installed in relatively low buildings. The mezzanine flooring can be designed to have a low profile ( 400mm for example ) and with a height to the underside of 2000mm and a minimum height above of 2000mm ,therefor the minimum height required would be only 4200mm. This would  have to increase to a higher building height if a fire rated ceiling was installed and would increase to 4400mm as an example. The benefits of installing a mezzanine floor are realized immediately, with increased space for expansion, additional office areas, storage facilities,assembly areas etc. The cost benefits are realized year after year. The costs saved in terms of rent and rates will easily cover the initial mezzanines investment and within a few years.

Mezzanines ( conventional mezzanine floors ) are not subject to the additional rent and rates.

Mezzanine floors are not generally subject to additional rent and rates, when they are designed as a free standing structure ( conventional mezzanine floor ) and not connected to the building, which they are installed within. They are classified as a raised storage platform in the same way as an over-racked platform or other storage facility such as pallet racking or shelving. When the mezzanine floor is directly or mechanically connected to the building portal frame, then they can ( or ) may be subject to additional rent and rates. Please speak to your Landlords for clarification. Raised storage platforms are designed specifically for special purpose plant and maintenance of existing work areas such as breweries for example.

Mezzanines and mezzanine floor ancillaries are designed to British or European standards and must also be approved under Building regulations which take into consideration, escape routs and fire protection. Approved building inspectors liaise with local fire departments and check the structural steel calculations for there conformity. Design criteria is based upon the recommendations of BRE Digest 437

Mezzanine Floor Construction.

A Mezzanine floor is either bolted directly and connected to the existing portal frame of the building or are free standing ( conventional mezzanine ) and can be dismantled at a later date and rebuilt is required. The Mezzanine area (usually single or two tiered ) are completed with balustrade for public access areas (  shops and retail outlets ) or are fitted with a conventional twin railed handrail system for storage mezzanines.

Mezzanine floors are generally manufactured from universal beams ( main beams ) and are connected within the webs of the beams by galvanized C-Section joists. The joists are bolted to the main beams by galvanized angle brackets called cleats. The secondary beams ( joists or purlins ) are set at 400mm – 700mm centers dependent on the loading requirements.

The mezzanine structure is supported at the correct design height by supporting columns. The support columns are generally box sections RHS with square base plates ( 200-700mm  depending on load and floor slab ) and top cap plates welded to them. Base plates are bolted to the concrete building slab with two through bolts per column and top cap plates are bolted to the universal columns with 4 bolts. Strut or cross braces are used for stability / sway for smaller floor areas. Decking, usually 38mm high density floor grade  chipboard board are screw fixed to the joists with self drilling screws generally 16 per board. Handrail is installed for edge protection to all exposed faces of the mezzanines structure as safety edge protection. Staircase combinations with mid or top landings complete the mezzanine floor and provide access to the mezzanines tiers.

Mezzanine Floor Staircases. 

The Staircases of a mezzanine floor provide adequate safety for people using the platform levels. The stairs need to conform to approved documents B,K and M, particularly when it provides a means of escape in the case of a fire. The stairs should never be used under any circumstances for moving heavy loads. Special lifting equipment should be provided for this purpose (package conveyors or goods lifts ) for example.

The staircase design is covered by  BS5395: Part 1, BS5395: Part 3 and BS5950: Part 5. General guidance on staircase design is contained within the new Approved Document Part K – 2013 (Section K1 – Stairs, Ladders and Ramps) of Building Regulations. This approved document supersedes previous guidance in Approved Documents Part M and Part K relating to staircases and guard railing.

For consideration of means of escape (MOE) in the event of fire, reference should be made to Approved Document Part B.

 Mezzanine floor Landings and combinations available

Building Regulations Approved Document Part K – 2013 Compliant Stairs/Handrail

There are now various options for staircases within Part K1 – Stairs, and the old Part K and Part M ‘ambulant disabled staircase’ has been superseded. The following stair options are now available:

General Access Stair – (Industrial)

General Access Stair – (Public Access)

Utility ‘Access’ Stair – (Industrial)

Utility ‘Escape’ Stair – (Industrial)

General guidance on the new requirement and characteristics are shown below:

All new mezzanine floors are now required to have a minimum of one General Access Stair. Where a floor has only one access stair, it MUST be of the General Access stair. Where a floor has more than one staircase, at least one must be of a General Access type. All other stairs can be deemed to be for escape purposes only, and be of the Utility ‘Escape’ stair type.

The width and number of stairs required is dependent on the number of persons using the floor area and travel distances.

Where the floor is a plant platform and the only access required is for maintenance, a Utility ‘Access’ stair is acceptable.

General Access Stair (Industrial)

The General Access Stair (Industrial) would have 1000mm between handrails, have OPEN rises – standard up stand within industrial/storage premises and CLOSED rises – within office/retail premises.

Treads with contrasting nosing will be governed by a rise of 150mm (MIN) to 170mm (MAX) and going of250mm (MIN) to 400mm (MAX).

The maximum number of rises allowable is 12 rises per flight, except in ‘small and/or restricted’ premises, where 16 rises are allowable.

Handrail needs to be contrasting and be a minimum of 50mm diameter (50×25 RHS is acceptable), and this must protrude 300mm beyond both the top and bottom tread nosing, unless it causes an obstruction to a common access route.

 General Access Stair (Public Access)

The General Access Stair (Public Access) would be the same as the General Access Stair (Industrial) but would have a clear width between handrails of 1200mm. This stair will always have ‘CLOSED’ risers as well.

 Utility ‘Access’ Stair (Industrial)

The Utility ‘Access’ Stair (Industrial) would have a minimum of 800mm between handrails, have OPEN riser treads with contrasting nosing will be governed by a rise of 150mm (MIN) to 190mm (MAX) and going of 250mm (MIN) to 400mm (MAX).

The maximum number of rises allowable is 12 rises per flight, except in ‘small and/or restricted’ premises, where 16 rises are allowable.

Handrail needs to be a minimum of 50mm diameter (50×25 RHS is acceptable).

 Utility ‘Escape’ Stair (Industrial)

The Utility ‘Escape’ Stair (Industrial) would be the same as the Utility ‘Access’ Stair (Industrial) but would NO contrasting tread nosing’s, NO restriction on the number of treads – subject to practical limitations e.g. no more than 25 rises.

Other considerations

An ‘Access Strategy Statement’ will sometimes overcome the requirement to provide a Disabled Persons Platform Lift by siting the provision of a General Access Stair (for Ambulant Disabled use) in lieu, and assuming that all facilities and areas are replicated on the ground floor accessible areas as are found on the mezzanine level.

Mezzanine Floor Hand-Railing ( Edge Protection )

Mezzanine floor hand-railing, or edge protection is there to form a safety barrier around the exposed faces of the mezzanine. The hand-railing is either standard for storage platforms or for public access or office is generally a vertical bar balustrade system or stainless steel and glass, The edge protection can also be mesh infill panels which offers a more cost effective barrier for public access use.

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