Roof Condensation: How does it form and what to look for?
Roof Condensation is moisture that develops at the roof ceiling area and is trapped by foil insulation or other types of radiant barriers. If left untreated, it can destroy the entire roof structure. Moisture rust and decay all metals including hangers, nuts, bolts and in severe cases the plywood that holds up the roofing deteriorates and needs to be replaced. This problem can be very costly.
How does it form? A roof structure contains a vapor barrier, which is usually a foil radiant barrier. As the roof heats up and absorbs moisture from the warm air it causes condensation when it cools. Heat is created in the air cavity between the insulation and the roof. Hot air holds the ambient water molecules, drawing moisture into the air cavity. Because of the insulation, the individual roof cells, the area between the foil and plywood roof are not able to vent and dry out.
A few topics of concern when accessing a buildings potential for roof condensation include, humidity levels, building construction, roof leaks and tenant operations. Dark or black streaking from purlin hangers or corrosion are major red flags that would indicate a building is in need of roof condensation repairs.