A barrier designed to protect insulation systems from water resulting from rain, snow, sleet and other weather conditions. A breather coating which has been emulsified will prevent water from entering into the system, while simultaneously allowing small quantities of vapour produced by heat and moisture from within the insulation system to escape. Water-based breather coatings are emulsified and consequently allow vapour to pass through the system. Solvent-based breather coatings are not emulsified and do not allow vapour to pass.