Important regulations for intumescent paint in steel buildings

The UK’s intumescent paint industry has undergone significant changes over the past two decades. Driven by technological innovation, it’s now a highly specialised sector that offers buildings targeted passive fire protection. 

Given its new degree of specificity, there are more regulations for the use of intumescent paints in steel buildings (the most common material for its application). In this post, we explain what these are and how they affect the design and fire protection of steel structures. 

Standards and best practice 

In the UK, intumescent paints need to be applied according to both standards and best practice. These are outlined in Approved Document A (which covers regulations concerning the structural elements of a building in England) and the Eurocodes (a set of European standards that regulate structural design in the EU). It’s worth noting that the application of Eurocodes is expected to continue in the UK post-Brexit, as it facilitates supplier relationships in the construction industry across the UK/EU borders. 

Fire Eurocodes 

The standards most relevant to the application of intumescent paint applications on steel structures are: 

• BS EN 1991: Actions on Structures. General Actions. Part 1.2 Actions on structures exposed to fire 
• BS EN 1993: Design of steel structures. General Rules. Part 1.2 Structural fire design 
• BS EN 1994: Design of composite steel and concrete structures. General rules. Part 1.2 Structural fire design. 

Critical temperatures of steel structures 

A key point highlighted in the standards pertains to the ‘critical’ (or ‘limiting’) temperature of steel structures. This is the temperature at which steel loses its load-bearing capabilities. 

Traditionally, the UK has taken a default approach to the critical temperature of steel structures, assigning a limit according to broad usage categories. According to British standards, steel beams carrying a concrete floor slab have a critical temperature of 620°C, whilst steel columns exposed on four sides have a limit of 550°C. These defaults are based on a number of assumptions (including load weight in a fire situation), and are stated by manufacturers alongside the thickness of their materials. 

The Eurocodes, on the other hand, offer more tailored guidance. These standards stipulate that the critical temperature of a steel structure is determined by how much load it’s expected to bear. According to BS EN 1992-1-2, for instance, a fully loaded, non-composite beam carrying a concrete floor slab in an office building has a critical temperature of 603°C, whilst a similar beam that is not fully loaded has a far higher limiting temperature. 

Ultimately, these limits determine the thickness of intumescent paint coating required in order to protect the integrity of steel beams and the structures they support. 

If you’re looking for expert spray applied fireproofing, get in contact with CLM Fireproofing. As the UK’s leading intumescent paint contractors, we combine industry-leading technology with years of experience to provide effective protection for both residential and commercial buildings.