April 17, 2026
This blog covers what raised access flooring is as well as the solution to prevent fire spreading through the void. What is Raised Access Flooring (RAF)? Raised access flooring is a system where a floor is installed above a structural subfloor, typically a concrete slab, creating a void between the two levels. This void is used to house and distribute essential building services in a clean, organised and accessible way. What is it used for? The void beneath a raised floor provides space for a wide range of services: - Electrical power distribution - Data and telecommunications cabling - HVAC systems (heating, ventilation and air conditioning) - Fire detection and suppression systems - Security and CCTV cabling - Plumbing and drainage - Environmental controls How is a Raised Access Floor Constructed? A raised access flooring system is made up of modular panels supported by adjustable pedestals arranged in a grid. - Pedestals are fixed to the subfloor and adjusted to create a perfectly level surface - Panels sit on top of the pedestals, forming the finished floor - Stringers (horizontal supports) may be added for extra strength and stability, particularly at higher floor heights. The void beneath the floor can range from as little as 20mm to over 150mm, depending on the project requirements. Can a Raised Access Floor cause a fire hazard in a building? Raised floors create a hidden void (the space underneath), and that introduces a few specific hazards: Cable buildup The void often contains electrical and data cabling. Poorly managed or overloaded cables can overheat and become ignition sources. Airflow spreading fire In many buildings (especially offices and data centres), the void is used for air distribution. That airflow can feed a fire with oxygen and spread smoke or flames quickly. Dust and debris accumulation Dust under the floor is surprisingly flammable. If not cleaned regularly, it can help a small ignition grow. Hidden fire development Fires starting under the floor can go unnoticed longer because they’re out of sight, delaying response. Combustible materials Older or cheaper floor panels and supports may contain materials that contribute to fire load. In modern buildings, much of the critial infrastructure such as cabling, ductwork and services runs unseen beneath raised access floors. While this design offers flexibility and efficiency, it also introduces hidden pathways where fire and smoke can spread rapidly if not properly controlled. This is where the Protecta FR Board RAF Barrier system plays a vital role. What is the Protecta FR Board and RAF Barrier? The Protecta FR Board and RAF Barrier is a robust firestopping solution built using a proven stone wool FR Board system. It is specifically designed to create a secure, certified seal within raised floor cavities. Installed beneath partition walls or across open voids, it helps maintain fire compartmentation and slows the spread of fire and smoke through unferfloor spaces. Why is it important? Raised floor voids can act as a concealed channel, allowing fire, smoke and sound to travel between compartments. By installing a dedicated barrier system: - Fire resistance is maintained beneath partition walls - Large underfloor voids can be subdivided into safer compartments - Critical services such as cables and ductwork remain properly firestopped - Air and sound transfer between spaces is reduced Product Availability The Protecta FR Board RAF Barrier is supplied as standard FR Board panels: 1200x600mm Thicknesses: 50mm, 60mm, 80mm, 100mm For installation, it is used in conjunction with compatable firestopping sealants such as Protecta FR Acrylic and FR Graphite, ensuring a complete and compliant system. All these products are stocked and supplied by Blazeout Ltd. Contact us for project support and material supplies – sales@blazeout.co.uk Free Downloads: Protecta Product Portfolio Protecta Handbook for Timber Construction Protecta Handbook for Linear Seals Protecta Handbook Service Penetrations
