DECRYPTAGE. The scientific and technical Centre for building (CSTB) has handed the government its report on the weaknesses of the fire regulations in buildings. What are the main lessons ?
One month after having been commissioned by the government to conduct an audit of the fire regulations in buildings, the scientific and technical Centre for building (CSTB) has handed in his copy. The report is available on the website of the organization. “The objectives of the mission are to identify potential weaknesses in the French legislation of residential buildings” and to make recommendations for evolution of the texts of the regulations. The objective is to minimize the risk of the scenario of the tower Grenfell breed in France.
If several specialists in the subject say that the fire regulations French is among the most demanding that exist, it would seem, however, to the reading of the report of the CSTB, that “hole in the racket” exist. In particular, in relation to the risk of the spread of the fire front, and some points relative to the buildings of the fourth family (1) – the category which lies below the high-rise buildings (IGH) of more than 50 metres. Batiactu offers a round-up of the horizon.
Thermal regulations have increased the mass of fuel in the buildings
The CSTB firstly takes note of the fact that thermal regulations amended “increased the mass of fuel” that is required of the insulating layers, wider and wider (4cm until 1988, then 7cm, 10cm, up to 15cm with the RT2012). This is true in the façade as well as indoors. The ITE, however, has been a priority of this regulatory development, in order to use a treatment of thermal bridges. “Whereas in the 80s the ITE remained very marginal, today, according to the database RSET 6, the market share of EIFS in new construction is of the order of 15% for buildings of 1st and 2nd families, 25% for buildings of the 3rd family, and 50% for buildings of the 4th family” (1), one can read in the report of the CSTB. The buildings of the 4th family are therefore particularly exposed.
In what concerns the insulation materials, the CSTB note two dimensions that are, for the moment, not taken into account in the regulation. It is of smoulder(onset of combustion without flame after a warm-up of the product) and the “maintenance in time of the performance of the fire behaviour during the life of a book”.
More combustible materials in the structure
Another trend that has developed on the basis of the latest regulations is the use of constructive solutions multi-materials or of combustible materials in the residential sector. The report points specifically to the construction project, in the framework of the Nouvelle France industrielle, tens of IGH wood. “These construction projects are today supervised for high-rise buildings”, however, specifies the CSTB, “but not for residential buildings, and particularly buildings of the 4th family”.
Thus, the use of more frequent occurrence of “combustible materials” in the construction should be the subject of”studies of fire safety engineering in the areas of resistance and/or reaction to fire”.
The question of the fire resistance of materials in the facade
“In the light of the feedback and some of the claims recognized, the requirements of reaction to fire of materials and façade cladding of residential buildings (…) appear to be insufficient”, which clearly states the CSTB. The subject is of importance, because it is thought that the façade panels to be the cause of the rapid spread of the fire, when the fire of the tower, Grenfell.
In addition, the CSTB notes that “the requirement of reaction to fire of coatings of facades is more binding among our european neighbours, in particular for residential buildings in which the height of the floor of the last level exceeds 8 metres”. Thus, the regulation fire French is obviously not the most demanding on all plans.
Finally, the CSTB is campaigning for a clarification in regulations to be made about the risk spread. “In the decree of 31 January 1986 as amended, in which the part on the facades has not been amended since 1986, the security objective for the propagation of the fire front is not explicit. In addition, the requirements of articles 11 to 14 on the facades of buildings relate to only a value of C+D (2) with respect to the minimum weight-based fuel that can be used on the front panel and to the requirement of reaction to fire external cladding”, one can read in the preliminary report.
“The composition of these fuels may greatly enhance the spread of fire via the façade but can also significantly increase the amount of fumes released”, also says the CSTB. Smoke that can be toxic.
Of existing buildings “very vulnerable”
“All the buildings including the date of the filing of the application for a building permit prior to December 31, 1960 were not the subject of an application for compliance with regulatory obligations relating to their protection against fire”, warning the CSTB. “These buildings are therefore potentially very vulnerable.”
Spread of fire from one building to the other
The agency’s report also considers that the requirements of fire spreading to a third party appear to be insufficient, “especially for buildings of the 4th family”.
THE NINE ECO CSTB :
Recommendation no. 1 : Revise the decree of 31 January 1986 as amended, based on the work of the various Working Groups led by the DHUP between 2011 and 2014. We will review all of the fire safety regulations for dwellings. The CSTB recommends also to introduce the establishment of a periodic review process of the rules of fire safety.
Recommendation # 2 : Clarify the applicable regulations for buildings to mixed-use. The co-existence of different laws makes the determination of the applicable regulatory uncertainty for the residential buildings of less than 28 meters, creating errors of interpretation. In the goal to avoid these situations, the CSTB recommends to revise the decree of 31 January 1986 as amended in order to clarify and complete fire regulations in the case of mixed use within a building for the use of the main dwelling which can integrate ERP or offices.
Recommendation n°3 : Build a regulation on the protection against fire of buildings suitable for renovation work, by reproducing the circular of 13 December 1982 in the regulatory corpus, and re-writing all the articles related to it.
Recommendation n°4 : Strengthen the requirements on the construction of the facades (refoundation of the technical instruction 249).
Recommendation n°5 : to Facilitate the taking into account of the innovation in the analysis of fire risk.
Recommendation n°6 : give up the French top fire reaction in the regulatory texts relating to the fire safety of buildings. The CSTB invites them to renounce the French top to switch on the classification system, said Euroclass, corresponding to the european classification of products. Indeed, the european evaluation allows to take into account the process in its final terms-of-use, while the evaluation of French is limited to the material.
Recommendation n°7 : carry out a fire safety audit of all the residential buildings of 4th family, under the responsibility of the owners and managers. It is intended to analyze and assess the risk of a fire from one-time to become non-controllable. It would consist of an examination of the facades and the state of the common parts of the building. On this basis, the cost should be of the order of € 1500 per building. The number of buildings of the 4th family is estimated between 10.000 and 15.000. A copy of the audit would be handed over to the services of the town hall which could, because of special circumstances, and under its police powers in general, prescribe the security of the building by fixing the time limit for the execution of these measures.
Recommendation n°8 : The CSTB advocates strengthening the civic education of the risk of fire, recalling the rules of good conduct in the prevention and in the event of the occurrence of a fire on the other hand, through information campaigns and awareness-raising carried out by the owners and managers of park but also in the institutions
the school’s application of the circular of 24 may 2006 on the education responsibility.
Recommendation n°9 : Supporting innovation through the acquisition of scientific knowledge essential to the mastery of the security.
(1) Dwellings whose floor the bottom of the housing the more top is located more than 28m and 50m above the ground level usefully accessible to the machinery of public services, rescue and fire-fighting.
(2) The C+D is the sum of two distances, geometric expressed in meters : the C corresponding to the vertical distance separating two front opening ; the D corresponds to the horizontal distance between the outside of the filler and the bare of the facade, at the base of the berries, overlapping, protrusions included if they form a barrier resistant to fire.