What Are The Fire Rating Requirements For Mezzanine Floors?
As a rule of thumb, a simple storage only floor can be installed without fire protection provided its dimensions do not exceed 20 by 20 metres and that the floor does not cover the whole of a building therefore being classed as a 2nd storey within the building. In some instances it may be necessary for the mezzanine to have a minimum of Class “0” Surface Spread of Flame Rating as determined by Part B of the Building Regulations. This is economically achieved with the use of a special reinforced foil laminate applied to the underside of the 38mm deck boards prior to delivery to site.
Any storage only floor which exceeds 10 by 10 metres will also require a smoke detection and emergency lighting installation to comply with current building regulations.
Storage only floors which exceed the rules above and floors which are intended to be used for retail, office accommodation, production or full time occupancy of any type will generally require a minimum of one hour fire protection.
Where the building has or is to have a sprinkler installation, this will need to be extended to include the mezzanine floor. This will usually negate or reduce the requirement for further fire rating in the form of ceilings etc.
60 minute fire protection is most often provided by using a decorative lay-in grid type suspended ceiling to the underside of the mezzanine structure, along with proprietary column casements and fascia. The most economical choice is for the casements and fascia to be covered using a Vermiculux lined two piece snap on galvanised steel or white Plastisol faced steel, both of which require no further finishes or decoration. Alternative finishes are available to give the required fire rating and to suit a given environment or look, such as mineral board, white board and Fireline board, which would require a painted or vinyl wall covering finish applied on site. These methods are more expensive and take longer to complete on site.
Intumescent paint can be applied on site to the exposed columns and steelwork instead but this is far less common.
An important consideration is that the any light fittings or services which may penetrate the fire rating membrane must have the appropriate fire dampening installed to maintain the fire rating. (Commonly back boxes or fire tents are installed with recessed light fittings).
In conjunction with the above requirements, it will also be a neccessity to consider the travel distances when leaving a floor in the event of a fire and escaping to a final fire exit point. This calculation will result in a minimum number of fire escape staircases being required. The use of the floor, hazard category and the occupancy levels will also determine the width of treads and whether the staircase(s) require a fire rated enclosure, giving a place of safety, should the worse happen.
aci™ work in close partnership with approved Building Regulation specialists to ensure that the correct and most feasible solution is chosen for your application.