Ceiling - An Important Element of Passive Fire Protection in a Building

In passive fire protection, a basic fire rated ceiling is defined as a board lining plus any supporting framework, including hangers, fixings and if insulation criteria is needed any non-combustible insulation material. Generally, ceilings are not considered as structural elements, but a finished non-load bearing surface concealing the underside of the roof structure or the floor of a storey above.

The fire rated ceiling may be attached directly to the structural member, suspended from it or be self supporting. The scope of a ceiling in fire protection is contributing to the horizontal compartmentation of a building or to a specific compartment.

The horizontal compartmentation is extremely important because avoid the spread of fire and hot gasses from a floor to another, giving time to the people present in the upper part of a building (which is the most dangerous in case of fire) to escape in a safe way.

There are various types of ceiling, with different scope and intended uses, which can increase the safety of a building. The right choice is based, first of all, on the fire rating of the compartment and on the scope of the ceiling (contribution to fire resistance to existing element or fire rated ceiling), but also on acoustic and aesthetical aspects.

As a general rule, the fire rated ceiling must be installed as described in the fire test report, assessment document, classification report or third-party approval. This includes hanging and fixing systems and if needed non-combustible insulation. Moreover, the total area occupied by fixtures and fittings relative to the area of the ceiling lining cannot be increased and the maximum tested opening in the lining is not exceeded. In other words, if a ceiling is tested with one luminaire cover every 10 square meters, the same percentage must be used in the application on site. If is tested without, no luminaire cover can be used. The same concept is valid for any other fittings or specific penetrations.

Ceiling can be continuous lining or tile and grid systems (600 x 600 mm or 600 x 1200 mm) and can be a simple board or a combination of different products (such as a rigid board and mineral wool, etc.).

Essentially, there are four basic types of ceiling used as a part of fire protection strategy:

The main purpose of these ceilings is to avoid flame spreading from the ceiling and to limit the contribution to the fire load in the compartment. They are classified according to the local “fire reaction” standards (Reaction to Fire). Reaction to fire relates to combustibility and ignitability of a material i.e. its contribution to fire growth.

From this point of view, the best classification is: “no combustible” (such as A1 according to the Euroclass, or similar). The EU classification system for building products according to EN 13501-1 calls for 7 Euroclass classifications (A1, A2 and B through F), based on various test and a so-called reference scenario.

These products give no contribution to the passive fire protection (resistance to fire), however can be used as part of a “fire prevention” strategy.

Ceiling classified only according to the fire reaction cannot be used for increasing the fire resistance of compartment elements. The ceilings used for fire protection, can be incombustible, to combine fire protection and fire prevention.

These ceilings, called “horizontal protective membrane”, have the ability to contribute to the fire resistance of horizontal structural building members up to 1 hour, 2 hours or more. More specifically, the fire resistance of the loadbearing element protected by the ceiling, can be classified based on the temperature within the cavity or on the element itself (in Europe the test standard is EN 13381-1).

These types of ceilings are used mainly for protection of steel beams supporting a loadbearing concrete floor slab or of concrete slabs or, in same cases, also of timber floors. 

The advantage of these ceilings is that they are protective materials, so can be used for protection of different loadbearing elements, with a wide direct field of application. The contribution to the fire resistance is valid only if the system is installed exactly as in the fire tests and assessment documents, including hanging (suspension system), junctions between membrane and walls/ edge panels, joints and jointing materials.

The ceilings are considered as part of the whole system (roofs/slabs + ceiling) and the fire classification is valid only for the entire load-bearing constructions (identical or similar to the one tested). So the rating is achieved by the entire system, which is both the structure above, as well as the suspension or fixing mechanism and finally the lowest membrane or ceiling.

In this case the ceiling is defined as “lining plus any supporting framework, including hangers, fixings and any insulation material”.

The ceiling may be attached directly to the structural member or suspended from it or be self-supporting. If it’s suspended, extremely important is the height of the cavity (the space between the upper surface of the ceiling and the underside of any floor, roof or its supporting construction) which must be at least high as the one tested; it’s possible to increase it but not decrease it.

The complete roofing system, including the ceiling, is tested for stability, integrity and/or insulation and shear forces shall not be greater than those tested.

No combustible or insulating material can be added to the cavity, unless the same amount (in term of fire load) was included in the fire test.

IMPORTANT: the contribution to the fire resistance is valid only if the system is installed exactly as in the fire tests, including hanging (suspension system), junctions between membrane and walls/edge panels, joints and jointing materials.

The ceiling is defined as a “non-loadbearing element of a building construction designed to provide horizontal fire separation”. The ceiling has a stand-alone fire-resistance rating and is used to provide protection from fire attack from below and/or above. In other words, these ceilings possess intrinsic fire resistance, independent of any building element above them.

The ceilings can be either suspended by hangers or fixed directly to a supporting frame/ construction or be self-supporting ceilings.

The systems (ceiling + suspending /fixing components) are required to provide an stability and integrity and if needed an insulation performance, independent from the supporting floor construction. These types of ceilings are tested according to BS 476:1987 part 22.

These ceiling systems allow for the protection to or from services contained within the ceiling void. More specifically, the ceiling should protect services in the ceiling void from fire in the room or corridor; equally, fire resistance may be needed to safeguard the corridor from burning electrical cables and other services located behind the suspended ceiling.

Since they may act as a horizontal partition, they provide also fire protection to any loadbearing element above them, where exposure is to fire from below.

The fire resistance classification is valid only if the system is installed exactly as in the fire tests, including hanging (suspension system), junctions between membrane and walls/ edge panels, joints and jointing materials.