How do I install a vapor barrier in steel walls?

A vapor barrier in steel walls requires a very clean surface and then the proper application of mastic. Once the mastic becomes tacky, you install the vapor barrier on the steel wall one piece at a time, ensuring that all air bubbles are out of it. Each piece of the barrier should butt up against or overlap its neighbor slightly for best coverage. You need a vapor barrier in steel walls because condensation and evaporation can quickly change the environment in a key storage building to one that is not viable. Be sure that the vapor barrier extends to any cement slab you may have used and that there is a barrier beneath the cement as well.