Insulated Panels and Internal Moisture

Metal facings are effectively impervious to penetration by vapour, and panel cores have a closed cell structure which does not permit significant transmission or absorption of vapour. However, to prevent the possibility of interstitial condensation, it is necessary to fasten and seal all laps and gaps, side-lap joints, transverse laps, and joints and ridges that are exposed to the internal environment.

When insulated panels are used as cold store insulation, a complete and continuous vapour barrier is essential to prevent inward moisture vapour pressure. Any discontinuity will result in a build-up of ice which can destroy the panel.

The bottom skins of composite panels have an integral side lap with a re-entrant sealing space which acts as a vapour control, but in high-risk applications such as food processing buildings, textile mills, and indoor swimming pools an additional sealer strip is required in the side lap joint.