When Are Vapor Barriers Used in Roofing?
Vapor barriers are most common on low-slope commercial roofs where the building’s use, climate or roof deckComponents - A roof deck is the structural surface connected to a building’s framing that supports the roof system installed above it. More makes hidden condensation likely. Common examples include low-slope roofsRoof Types - Low-slope roofs (flat roofs) are a type of roof system with less than a 3:12 pitch, most commonly found on commercial and industrial buildings. More over indoor pools, humid manufacturing spaces, or new concrete decks that can continue releasing moisture after the roof is installed.
Warm air can hold more moisture than cold air. When vapor moves into colder parts of a roof systemRoof Types - A roof system (roof assembly) is the entire series of roofing layers and components above the roof deck that work together to weatherproof the building. More, it can condense inside the substrate instead of appearing as a more visible roof leak.
A vapor barrier slows that invisible vapor movement before water collects inside the roof system. Because the same layer that slows vapor can also slow drying, vapor barriers are not added to every roof; they are only added when the risk of trapped moisture is greater than the benefit of allowing the system to self-dry.