An expert guide to fire protection between floors

In the event of a fire, the spread of flames and smoke must be stopped as quickly as possible. This can be achieved through compartmentation – the application of fire stopping materials to walls, floors, and cavity barriers. Dividing a building into a series of compartments reduces the risk of air pressure pushing fire and smoke through a building (known as the ‘chimney effect’), allowing for quick and effective risk management.

While the overall objective of compartmentation remains the same for walls, floors and cavity barriers, each element has different requirements for effective fire stopping. This article will outline the specific methods, systems, and products for fire protection between floors.

What are the requirements for fire protection between floors?

What distinguishes fire protection for floors from walls and cavity barriers is the need for sufficient load-bearing capabilities. This is not the only requirement, but it is vital that a floor is not only protected from fire but can also accommodate people standing, walking and working.

The ASFP guide to ‘Ensuring Best Practice for Fire Protection in Buildings’ defines the function of floors by their ‘structural load carrying capabilities’, as well as the ‘stiffening of the general structure of the building’. A fire stopping strategy must incorporate the need for load-bearing capabilities, as this excludes certain passive fire protection products (e.g. coated fire boards) being used on floors.

The material of the floor is also an important factor in identifying an appropriate fire stopping solution. Concrete, for instance, offers a superior level of fire resistance and often does not need additional protection, whereas certain types of composite and steel flooring will require an intumescent coating – subject to a specialist review carried out by a designer.

Safety guidelines for fire protection between floors

Safety is paramount when implementing fire stopping systems. A contractor will often work to achieve a specified load-bearing pressure. This will usually be measured in Kilo newton per meter squared (Kn/m2).

Wet-applied fire stopping systems need time to cure and harden before they can expect to carry any weight. During this process, floors must be cordoned off and marked with appropriate warning signs. Any additional weight on the floor runs the risk of injury, as well as potentially compromising the floor’s fire stopping capabilities. If the applied fire stopping seal cannot withstand an acceptable load, access must be blocked with a permanent guard rail until this is rectified.

What products are used for fire protection between floors?

A variety of fire-resistant compounds and mortars can be used on floors. Materials traditionally used on walls (e.g. intumescent sealants, pipe collars and wraps) can often be used on floors, providing that they have been wear-tested.

These compounds undergo an exothermic process – when exposed to high temperatures they form a carbonaceous layer to provide additional support. While this is the main benefit of these compounds, they can also be installed at various depths. This means that they can be applied to multiple floors within a tall building. As well as this, they improve the floors’ waterproofing and soundproofing capabilities. Here are a few examples of products commonly used for fire protection between floors:

FSi Silverseal® HS Compound

FSi Silverseal®HS (High Strength) Compound is a gypsum-based mortar material used in both walls and floors. It has a working time of approximately 90 minutes (setting in around 45 minutes) and is easy to both mix on site and pour.

FSi Silverseal®HS can be used to reinforce large span openings, offering superior strength, load-bearing, and smoke sealing capabilities. This makes the compound suitable for risers and areas of foot traffic. It is also easy to apply to appropriate areas, due to its versatile workability. FSi Silverseal®HS also has multiple secondary benefits through both thermal and acoustic insulation

Polyseam/Protector® EX Mortar

Protecta® EX Mortar is a dry white powder, made using perlite and a range of inorganic compounds. When mixed with water, the powder expands to form a tight seal, protecting the floor against heat and smoke. It also sets incredibly quickly, and following the curing process, it can be easily sanded or drilled.

Over the last 30 years, CLM Fireproofing has established themselves as market-leading experts in passive fire protection. We employ a team of FIRAS-certified specialist installers, who work to ensure construction projects are in full compliance with the latest industry regulations. To find out more about our compartmentation and fire stopping services, contact the CLM Fireproofing team today.