Understanding regulatory compliance for structural steel
Steel beams are incorporated into a wide range of construction projects, from covered parking areas to multi-storey buildings, due to their strength and durability. However, in the event of a fire, beams can lose their structural integrity when exposed to extreme temperatures. For this reason, fire protection regulations include guidelines for how steel can be protected to withstand fire damage. These guidelines are then adhered to with the help of passive fire protection specialists.
Architects take fire protection into account in their designs, and the relevant fire protection methods are implemented during construction, but the coatings and coverings used to protect structural steel may become damaged or degraded. Therefore, it is fundamental that Responsible Persons (RPs) initiate inspections for steel beams (and remediation where required) in line with relevant legislation. In this guide, we will be exploring regulatory compliance for steel.
What are the main fire protection regulations for steel in the UK?
UK regulations stipulate how long steel should be able to resist exposure to high temperatures based on the height and structure in question. RPs must initiate passive fire surveys, installations and remedial works, so that these requirements are met.
The Building Regulations 2010
According to Requirement B3(1) of the Building Regulations for England: “The building shall be designed and constructed so that, in the event of a fire, its stability will be maintained for a reasonable period.” This acts as a foundation for regulatory guidelines such as Approved Document B, which maps out fire resistance specifications for various buildings in greater detail.
Approved Document B
Approved Document B provides additional guidance based on the type of structure and the presence or absence of sprinkler systems. For example, if an office building is 18 to 30 metres high and has no sprinkler system, it should resist fire damage for at least 90 minutes. In comparison, 120 minutes of fire resistance is required in an office building that is taller than 30 metres and has a sprinkler system.
Approved Document B takes a holistic approach that specifies how long a building should withstand fire. When buildings depend on structural steel beams or columns for support, fire protection strategies must ensure that they do not become a fatal weakness that compromises the overall fire resistance of a building.
BS 9999
The British Standards Institution (BSI) has elaborated on some of the fire safety guidelines in Approved Document B. The relevant document is BS 9999, which includes a table that specifies the requirements for fire resistance across a wide range of buildings. Factors include the depth of basements, the height of a building’s top floor, and the way the building is used. For example, at the lower end of fire resistance requirements, open-sided car parks with a height of 10 metres or less will not require fire-resistant steel beams. Residential and commercial buildings taller than 30 metres, on the other hand, must resist fire for 120 minutes. This is where fire protection for structural steel becomes a vital requirement.
How are steel beams protected as part of regulatory compliance?
The most frequently-used methods for enhancing the fire resistance of steel are intumescent coatings, cementitious coatings and fire protection board systems.
Intumescent paint is inert at temperatures below 200 degrees but it swells when exposed to heat, forming a protective layer around steel beams that’s up to 50 times the original thickness of the coating. The swollen char layer has very low thermal conductivity properties and insulates structural steel, preventing its temperature from rising to critical levels. Intumescent paint can protect steel beams for up to 120 minutes, provided that the paint is compatible with any primers and topcoats. Therefore, there must also be sufficient space around the coated surface to allow for the coating to expand around the structural steel.
Fire protection boards are made from mineral-based materials that keep heat away from steel beams during fires. When installed by experienced professionals, fire protection boards can protect structural steel beams for up to 180 minutes. Their main advantage is that they’re manufactured under closely controlled conditions and will have the necessary tolerances without any need for checking properties such as their thickness.
Cementitious coatings are applied via trowel or spray. There are commercial benefits to applying cementitious coatings compared to other products such as intumescent paint. Firstly, surfaces often do not need to be prepared for the application of cementitious materials. This reduces the cost and waste traditionally associated with methods such as shot blasting. As well as this, once the desired thickness of the cementitious materials has been determined, the application process is quick and effective. The duration of protection offer is up to 240 minutes.
Fire Safety Requires Proper Protection of Structural Steel
Protecting structural steel is key to achieving the fire resistance timeframes stipulated in building regulations. Maintaining effective fireproofing requires in-depth knowledge of fire protection technologies coupled with technical expertise.
CLM Fireproofing is the UK’s leading provider of passive protection solutions for structural steel, including intumescent paint application , cementitious coatings and fire boarding. We offer end-to-end technical guidance and installation services, so that buildings remain compliant with the latest fire protection regulations. Contact our team today to find out more.