New PFKG Guidance Highlights Critical Fire-Test Evidence Gaps

The Passive Fire Knowledge Group (PFKG) has published two new Knowledge Shares to help design and construction teams identify where external wall cavity barriers and lift landing doors risk being specified outside the scope of their fire-test evidence. Both publications reinforce a simple principle, that fire-rated products should be installed only in constructions supported by appropriate test or certification evidence. If these matters are not addressed at an early stage of design, projects may face compliance issues, additional testing or assessment, redesign, programme delays and increased cost.

PFKG Knowledge Share 14: External Wall Cavity Barrier & Fire Stop Substrates

This Knowledge Share highlights that most cavity barriers and fire stops used in external walls do not have a dedicated test standard. Products are commonly tested to BS EN 1366-4 between defined standard supporting constructions, often rigid concrete walls or floors. Project designs, however, often incorporate asymmetric steel framing with sheathing board, rainscreen panels or sandwich panels. These arrangements may fall outside the applicable test or certification evidence.

To avoid problems, design teams are reminded to review any non-standard arrangement with the manufacturer and fire engineer as early as possible in the design process. Knowledge Share 14 builds on previous guidance from PFKG, ASFP Advisory Note 34 and also identifies the separate standards applying to curtain-wall junctions and open-state cavity barriers.

PFKG Knowledge Share 15: Lift Landing Doors – Fire Test Evidence and Field of Application Limitations

This Knowledge Share highlights that lift landing doors help to preserve the fire-resisting separation around lift shafts. They are generally tested to BS EN 81-58 in standard masonry or concrete walls, but are often installed in lightweight blockwork, steel-framed or drylined walls where supporting evidence may be limited. It also notes that raised lift-door thresholds above the structural slab are not typically represented in standard fire tests and may create a weakness in the compartmentation line if not properly addressed.

To avoid problems, design teams should obtain the manufacturers test certification and field-of-application report before selecting the shaft-wall construction. Fire-rated lift landing doors should be installed in standard masonry or concrete walls unless suitable evidence supports an alternative. Where thresholds are raised, a rigid upstand should maintain the fire-resisting separation beneath them unless a tested alternative is available.

Key Takeaway

Across both publications, the message is clear: That fire-test evidence is only applicable within its defined field of application. Early collaboration between fire engineers, designers, contractors and manufacturers is therefore essential.

“A products fire rating cannot be considered separately from its supporting construction and the field of application of the test evidence,” said Will Pitt, Chair of PFKG. “By checking the evidence before wall types and interfaces are fixed, project teams can resolve gaps while options remain open, rather than when work is already under way.”

Knowledge Shares 14 and 15 are free to download at www.pfkg.org. PFKG encourages fire engineers, designers, specifiers, contractors and manufacturers to review the guidance early, test relevant project details against the available evidence and share the publications with their project teams.