The London Fire Brigade has issued a strong call for more rigorous fire-safety testing in the modular construction sector, emphasising that each off-site-built unit should undergo individual assessment rather than reliance on generic or blanket approvals. This development reflects growing concern over how modern methods of construction (MMC), such as volumetric modular systems, perform in fire incidents.
Core Concerns Raised by LFB
- Modular buildings often involve factory-built units (modules) that are assembled on site. While these offer speed and efficiency, LFB highlights that their fire behaviour may not mirror that of traditional construction. Testing regimes and regulatory frameworks remain less established for modular systems.
- Key issues include hidden voids, unsealed penetrations, compromised cavity barriers and unverified joints — all of which can accelerate flame-spread or smoke penetration within modular assemblies.
- LFB’s thematic review of modular building fire-safety emphasises that product or component tests may not sufficiently represent the real world stacking, connection and installation conditions of volumetric systems.
- Consequently, the brigade argues for individual module testing and full-system verification, rather than assuming a tested configuration can apply universally across multiple units or projects.
Why This Matters for Modular Construction
- With pressure to build homes and commercial buildings more quickly, modular construction is increasingly used. However, speed should not compromise occupant safety. Fire-safety confidence underpins insurance, regulatory compliance and long-term asset value.
- Failure to address these issues may lead to higher risk of significant fire incidents, especially in buildings where modules have complex interfaces, shared services, or high-rise stacking.
- For developers, manufacturers and regulators, LFB’s stance adds to the growing agenda: ensure that modular systems are subject to rigorous scrutiny, and that fire-performance assumptions are validated in the actual configuration and operating context.
Actionable Implications for Stakeholders
- Manufacturers & system providers should ensure that modules are tested in conditions that replicate site assembly, stacking, connectivity and service penetrations — not just factory design-only scenarios.
- Developers must engage early with fire engineers and regulators when specifying modular systems, clarifying the responsibilities for testing, installation and compliance.
- Regulators and insurers should consider whether current modular-construction approvals and standards adequately cover the full life-cycle risk of modular buildings — from off-site manufacture through to site installation and occupancy.
- Contractors and site teams need robust verification of module installation, independence of fire compartmentation and documentation of interface details between modules and fixed building systems.
Key Challenges Ahead
- Implementing individual testing increases cost, effort and lead-time — balancing safety with the efficiency advantage of off-site methods will require smart planning and collaboration.
- Standardisation is still evolving: modular systems vary widely in design, materials and connection methods, which means test-protocols may need to be customised rather than one-size-fits-all.
- Data and transparency are limited: long-term performance, fire-behaviour in real incidents and comparative metrics between modular and traditional builds remain under-researched.
Final Thought
The LFB’s call underscores that innovation in construction must be matched by rigour in safety assurance. Modular construction holds compelling advantages for speed and cost—but its safety credentials will increasingly rest on how well each module and its assembly as a whole perform under fire conditions. As modular builds become more common, those that embed detailed fire-testing, quality control and clear accountability from design through installation will stand out as the benchmarks of responsible practice.