In order to maintain the breathability and waterproof properties of functional clothing, it is imperative that you wash your soft-shell clothing at regular intervals. As described, however, this should only occur when truly necessary.
Caution: You should never wash soft-shell jackets with fabric conditioner!
Many have unfortunately made this mistake and are then obliged to throw their much-loved garment straight into the bin. Fabric conditioners are toxic to any soft-shell membrane, as it causes a thin film to settle over the fabric of the inner membrane during washing. This film causes perspiration to bead inside the garment instead of wicking it outside. Once again: Keep away from fabric conditioners, they destroy the breathability of the jacket!