... IRC RR-219: Guide for Sound Insulation in Wood Frame Construction March 2006 When floor toppings are added (reducing flanking via the floor-floor path), the effect of the flanking transmission ... RR-219: Guide for Sound Insulation in Wood Frame Construction March 2006 Summary – Changes to Control Horizontal Flanking (One apartment beside the other, Airborne sound source) For the ... IRC RR-219: Guide for Sound Insulation in Wood Frame Construction March 2006 With the joists perpendicular to the separating wall, the improvement in Apparent-STC due to adding toppings is greater,...