Underside Of Roof Damp

Warm wet air rises and meets the cold roof and cools.

Underside of roof damp.

The same phenomenon happens with roof systems. Warm air can contain more moisture than colder air. Essentially condensation occurs at night when the temperature inside a building is warmer than outside. Warm moist air enters the roof space through gaps in loft hatches or where bathroom plumbing or other services go through the roof space.

Condensation will arise as a result of warm moist air penetrating up through the ceiling. If attic air is humid and roof sheathing is cold condensation or frost can accumulate on the underside of the sheathing. As it cools it can t hold as much moisture. This leads to the formation of damp spots on the surface of the roof.

The cause depends on whether you have an unconditioned attic or a conditioned attic. The source of the attic moisture is usually indoor air that enters the attic through ceiling cracks. When humid air from the interior makes contact with the underside of the roof surface the water vapor it s carrying turns into liquid water explains jose f. Picture a cloud of moisture floating overhead between the rafters.

When this warm air reaches the spaces in the roofs it gets in contact with cold air and condenses. Think of a cold drink sitting out on a summer day. Ponce technical specialist with professional roof consultants. Another leading cause of condensation in roofs is the use of wood burner cookers.

That excess moisture ends up as drops of condensation on the roof.