Metalwork, particularly aluminium, can have an unpredictable effect on loop system performance. Other external factors can affect the performance of an induction loop system. Reinforced concrete floors, steel lintels, corrugated steel cladding and other types of metalwork all have an effect on the performance of the induction loop system.
Any aluminium based building product extensively used throughout the building may have a dramatic effect up on the performance of the induction loop system. In extreme cases it may prohibit the installation of a loop system because its effect has degraded the sound quality and strength to an unacceptable level.