Heat and humidity are the two greatest enemies of videotape. The recommended storage conditions for videotape are 18°C-24°C with a relative humidity of between 35 per cent and 45 per cent i.e. an even temperature with low humidity. Satisfying these conditions in a typical domestic environment is difficult. However, in a building with two or more levels, the lower or mid floors are generally cooler than the top floor.
Storage places to be avoided include:
directly on concrete floors (susceptible to spills and water damage and high humidity)
It is also a good idea to spool tapes at low speed or play from start to finish before storage as this will ensure that the tape is correctly wound inside the cassette.