ift Rosenheim – 50 years of service to the industry

The collection of examples of DIN 4109:1989 in supplement 1 [4] contains no construction samples for internal doors; the proof of the sound insulation has to be made with laboratory measurement. The research project regarding sound insulation of internal doors should determine the possibilities of a verification procedure on basis of general design features.

The sound transmission paths at internal doors were examined in the research project with the aim of generating a similar table method for the technical proof for doors, as submitted in supplement 1 for windows and roller shutter boxes. The foundations should be laid and, if possible, proposals should be prepared. The research project started in 1994.

The analysis of sound transmission paths through a serviceable internal door result in a total of 5 independent sound transmission paths (image 1). It showed that the sound transmission paths through the door panel as well as through rebate and floor joint have the largest influence on sound insulation of a serviceable internal door.

The industry has already developed sealing profiles and drop down seals. Due to the linear constructions, a description of the sound passage by a joint sound reduction index R_S is offered that was already defined in various publications [14, 15, 25] for the characterization of the sound passage via joints.

Various publications regarding sound insulation of doors [16, 18, 20, 21] as well as sound reduction of joints [17, 19, 21, 23, 24] were published until now in addition to the publication of the research report [8]. Not only door manufacturers were addressed but also end-user and planner whom the special features in planning and the proof of the sound insulation of doors should be brought closer. Priorities were the evaluation of joint sound problem (especially rebate and floor joint) as well as installation joints. A simple verification method via nomogramm was proposed in addition to the description and establishment of the joint sound reduction index R_S.

Furthermore, the results of the research project were included in various standards and regulations.

• Revision of VDI-Guideline 3728:2012 „Sound insulation of movable room boundaries”; this take place in cooperation with ift Rosenheim
• Revised version/revision of DIN 4109 (see 3.1)
• Development of product standard of internal doors DIN EN 14351-2 (see 3.2)

The revised version of the component catalogue DIN 4109-35 [12] recently contains a table method, where the sound insulation of internal doors can be determined by the parameters of the single components (door leaf, floor and rebate seal). This verification method is directly based on the ift-research project [8] and separates according to the sound transmission paths shown in image 1. The minimum requirements for the sound insulation of the door leaf as well as the sound reduction of joints (valued sound reduction index R_S,w) for rebate and floor seal can be taken from table 1 on the basis of the planning value for the door element in functional condition (required R_w). Declared values for the sound reduction of joints can be tested or taken from table 2. The evidence of the sound insulation of the door leaf is made by a sound insulation test according to DIN EN ISO 10140-2 [5].

Table 1: Sound insulation of single sashed internal doors (flush door) without measurement (table 4 of DIN 4109-35 [12])

The harmonised and in the context of the EU legislation developed product standards are gaining more and more importance. They serve an uniform labelling of the performance characteristics. A similar table method for the forecast of the sound insulation is presented [11] for doors on basis of the mentioned research project. Thus, a manufacturer can determine the sound insulation of the suitable door for the CE marking with the sound reduction indexes of the single components.

This publication gives an overview on activities performed at ift Rosenheim but also on European and international level within the last 25 years regarding sound insulation of doors - especially internal doors. They are preliminary resulted in the national and European proof standards DIN 4109 and DIN EN 14351-2, which should be completed in 2016. The activities will also be continued in the future: The constructions will be developed and also the requirements for the acoustic insulation will increase due to an increased need for silence and confidentiality, but also influenced by new specifications in the field of serviceability.