Bio-based materials: new materials, new risks?
Over the last ten years, so-called “bio-based” materials, meaning those derived from animal or plant biomass, have become increasingly present on construction sites and have been nibbling away at the thermal comfort market. Despite being considered healthier, these eco-materials still require extreme vigilance in terms of fire safety.
Specific processes to reduce risks
These bio-based materials, derived mostly from ancestral and regional techniques, have not, contrary to what we might think, automatically resulted in a zero carbon balance. In effect, even if they have the benefit of favouring local supply chains and plant-based products help to store CO2, they generally require industrial processing and the addition of chemicals to guarantee their behaviour in response to fire so that they can be used as building materials. This is particularly the case for sheep’s wool, cellulose wadding, straw and recycled textiles, which need to be specially treated to improve their reaction to fire, and potentially undergo specific treatments to reduce the risk of degradation caused by termites, mould or mites.
Another technique which can reduce the performance of materials in terms of reaction to fire in the context of a tailored construction system is the addition of a fire screen, which may also be made of wood. Even in the fire regulations for ERPs (buildings receiving members of the public), which are very strict, a guide to the use of combustible insulation in ERPs is annexed to the order of 6 October 2004.
An updated legislative framework
Particular attention must be paid to facade insulation to avoid tragedies such as that affecting Grenfell Tower in London, which was the scene of a deadly fire. In France, facade construction regulations (IGH1 and ERP) are governed by Technical Instruction no. 249 which was modified in 2010 to take into account new facade insulation construction systems which increasingly incorporate bio-based materials.
The wood sector that uses this type of natural material to insulate its wooden panels is the most active in the field and a guide produced by the CSTB2 and published in July 2016 proposes wood construction solutions to control the spread of fire through facades. This document constitutes a laboratory assessment pursuant to TI no. 249.
For residential buildings, and mainly small shared properties and single-family homes, there are regulations in force that require the use of materials whose reaction to fire has been proven through approved laboratory testing.
From an insurance perspective, this concept, and particularly the implementation of the so-called “routine technique3” process, is important for the application of the ten-year guarantee element of builders’ policies. Failing this, a case-by-case examination of the processes implemented using “non-routine techniques” will have to be carried out by the insurer and the builder.
There is, therefore, nothing to prevent the implementation of these new so-called bio-based materials, provided that the appropriate implementation rules are observed and regularly updated by market players.
Jean Baptiste BRODE, Loss Adjuster, Construction Specialty Manager
1 High-rise buildings
2 Scientific and Technical Centre for Building – in partnership with the FCBA
3 According to the FFSA, these are products that are subject to an “Avis Technique” [Technical Advice] (ATec) or a “Document Technique d’Application” [Technical Application Document] (DTA) and have not been put under surveillance by the Commission Prévention Produits [Production Prevention Commission] (C2P) as well as French standard implementation rules (DTU) or professional rules validated by the C2P.