BUILDING PHYSICS 37 Fire protection evaluation of component joints To prevent fires in buildings, it is not sufficient to know the fire resistance duration of the respective components. The interaction of the components joined with each other must also be considered, meaning the fire behaviour of connecting parts and installations. Spreading of the fire and smoke gases through hollow spaces and joints must be prevented. Thus, the same requirements of fire resistance are posed for connections and passages as also apply to the respective individual components. Figure 24 – binderholz processing guideline: Exterior wall-to-ceiling connection detail To prove the fire resistance of the component joint, for example, between a CLT BBS ceiling in visual surface quality and a wall planked directly with 12.5-mm gypsum fire protection boards, several fire tests have been conducted. It was shown that with a force-fit connection of the elements (fastener spacing up to 500 mm), a burn-through in the connecting joints can be prevented for 60 minutes. For the solid timber construction, a Sylomer bearing was inserted between the timber elements and the connecting joint was sealed with common retail acrylic or an intumescent product. It was shown that both versions fulfil the requirements for fire resistance. Source: binderholz processing guidelines At Technical University Munich, various connecting joints between walls and ceilings made of CLT BBS have been tested. The test duration was 60 minutes, the protection targets for the tested joints to be reached are smoke-tightness and preventing a burn-through for 60 minutes. The fire protection board planking (gypsum fibre boards) abutted on the CLT BBS of the ceiling. Fire protection acrylic was plastered onto half of the joint length, the corner joint between the timber and the gypsum fibre board and the gypsum fibre board was set abut on the timber “dry” without sealing on the other half of the joint length. An elastomer bearing was installed in the joint, which was protected on both sides by mineral wool strips. This protection measure is not required if the gap created by the elastomer bearing is filled with stone wool or fire protection mass. If no elastomer bearing is installed, no sealing measure is required. Figure 24 shows a planned joint and Figure 25 shows a realised butt joint before a fire test. Source: Technical University Munich Test results and rating in reference to the butt joint: The butt joint of the wall covering on the uncovered ceiling did not result in a hollow space fire and continued smouldering in the connection area. No traces of fire could be found on the elastomer bearing. The described design of the butt joint with and without fire protection acrylic reached the protection targets, meaning smoke tightness and prevention of burn-through for 60 minutes. The company Rothoblaas has conducted its own tests for its XYLOFONN elastomer bearings, in which the elastomer bearings were installed as a separating layer between solid timber ceiling elements not covered with planks. This design was tested successfully for smoke tightness and insulating effect for a fire duration of 60 minutes. Figure 25 – Preparation for the fire testing of the elastomer bearing Source: Technical University Munich
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