DESIGN PROCESS
The same applies to sandwiching combustible class E components between class A1 components, as this does not meet the regulations. If this was the case, we would continue to use laminated glass balustrades and we could continue to use combustible insulation materials between non- combustible cladding sheets etc. Nowhere in the regulations or AD B guidance does it refer to or state that a specific width of membrane constitutes a seal. A membrane is a membrane irrespective of its width and primary function. At the end the project the designer should pass on all relevant information about the product and its performance to the client, as stated in Regulation 38 (See Appendix). Safety information, including fire safety, is often channelled via the principal contractor to the principal designer for inclusion in the health and safety file. Regulation 38, although a separate duty, is usually dealt with in the same way. The H&S file should be referenced. BEAM AND SLAB DEFLECTION IN A FIRE STATE Approved Document B (Volume 1 & 2) provides the guidance shown in the extract from Approved Document B, where a ‘compartment wall’ abuts the underside of a slab. The deflection of the slab (or beam) in a fire state should be considered in conjunction with the cold state deflection. The project’s structural engineer should provide this information. EVIDENCE OF COMPLIANCE Designers should satisfy themselves that the specified products have evidence of compliance with fire test reports from the relevant fire tests listed in this document or using third-party certification schemes. There are several industry-recognised third-party certification schemes available, covering a wide range of through-wall systems. Independent third-party certification schemes formally assure the fire performance, quality, reliability and traceability of performance in systems and products.
Junction of compartment wall or compartment fllow with other walls 7.12 At the junction with another compartment wall or an external wall, the fire resistance of the compartmentation should be maintained. Fire stopping that meets the provisions in paragraphs 9.24 to 9.29 should be provided. 7.13 At the junction of the compartment floor and an external wall with no fire resistance, the external wall should be restrained at floor level. The restraint should reduce movement of the wall away from the floor if exposed to fire. 7.14 Compartment walls should be able to accommodate deflection of the floor, when exposed to fire, by either of the following means. a. Between the wall and the floor, provide a head detail that is capable of maintaining its integrity while deforming. b. Design the wall so it maintains its
integrity by resisting the additional vertical load from the floor above.
Where compartment walls are located with the middle half of a floor between vertical supports, the deflection may be assumed to be 40mm unless a smaller value can be justified by assessment. Outside thsi area, the limt can be reduced linearly to zero at the supports. For steel beams that do not have the reguired fire resistance, refeerence should be made to SCI Publication P288.
Extract from Approved Document B
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