Underside Of Roof Damp

The same phenomenon happens with roof systems.

Underside of roof damp.

That excess moisture ends up as drops of condensation on the roof. Warm wet air rises and meets the cold roof and cools. As it cools it can t hold as much moisture. 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.

When this warm moist air hits the cold air in the roof space water droplets condense on the nearest cold surface the roofing felt. If attic air is humid and roof sheathing is cold condensation or frost can accumulate on the underside of the sheathing. Think of a cold drink sitting out on a summer day. When this warm air reaches the spaces in the roofs it gets in contact with cold air and condenses.

Warm moist air enters the roof space through gaps in loft hatches or where bathroom plumbing or other services go through the roof space. The cause depends on whether you have an unconditioned attic or a conditioned attic. Essentially condensation occurs at night when the temperature inside a building is warmer than outside. This leads to the formation of damp spots on the surface of the roof.

The source of the attic moisture is usually indoor air that enters the attic through ceiling cracks. Such cookers often allow for the quick rise of moist air leaving behind the cold air. Condensation will arise as a result of warm moist air penetrating up through the ceiling. Picture a cloud of moisture floating overhead between the rafters.

Warm air can contain more moisture than colder air.