142 User Manual Smart drawing is one of the keys that make possible to successfully apply the ISO 12354 to real buildings. We have to constrain the coincidence of walls from one floor to the others, otherwise the method in ISO 12354 cannot be applied. If you try to draw a wall which is slightly tilted respect to a wall in the lower floor, we will snap the upper wall to be perfectly coincident with the lower. In the same way, we do not allow very small walls, which may pervert the ISO 12354 computation method (just recall the influence of wall area in R'), so that, we do not allow to draw lines of less than 20 cm. This two measures, which both have higher priority than the ortho lock, lead to a natural simplification of the building design which corresponds with a proper specification of the acoustical design according to ISO 12354. At the beginning, you may be a little puzzled about this behaviour of the drawing pen. But as soon as you get used to its obstinate way, the design process is greatly enhanced and fastened. 14.2 "Some materials are missing in the building description"? This warning appears when you press Calculate button and one or more of the constructive solutions of the building are unassigned. The first empty material element is highlighted in the drawing. All the elements (except linings) must be assigned. Also the roofs, even if the floor of that roof is not the last one: SONarchitect verifies this for avoiding user errors when patios appear. 14.3 How can I model the junction I want? SONarchitect ISO computes all the acoustic insulation levels according to EN ISO 12354. The sound transmission between flanks is determined by the vibration reduction index of the junction. This Kij coefficient is calculated by means of the models in the norm. SONarchitect only identifies the topology and materials in the junction and whether there is an elastic junction or not and calculates the Kij coefficient. You can see some of the junctions examples in the Junctions section. 14.4 What do represent the lines of the drawing? You could also make this question as, which are the real dimensions of the walls, slabs...? These lines are representing the midlines of every vertical partition: wall or façade. When you are drawing over a DXF template you can see the drawing of a wall with its real © 2012 Sound of Numbers S.L.