In an un vented roof foam can serve as the air barrier and vapor retarder and prevent moisture from getting in to the roof cavities.
Vented vs unvented roof.
Unvented roof assemblies are not prone to these problems because the ventilation openings have been eliminated.
In a vented roof foam can seal the openings and serve as an air barrier and a vapor retarder in addition to its insulating function.
In other words the entire vent opening doesn t count as vented space.
In areas subject to wildfires burning embers can be blown in through these openings potentially starting roof fires.
A vented attic system refers specifically to having working vents in the attic.
That said air resistance and interference such as vent grates reduces the area of true ventilation.
Too many people believe the importance of roof ventilation is to increase energy efficiency during the summer.
Unvented roofs which provides a detailed explanation of each.
Because the drying capacity of unvented roof assemblies is inherently lower than vented ones it is especially critical to control built in moisture during construction.
In other words vented roofs may well be the best design for one home while an unvented roof will be a better solution for another home.
Vented attic roof designs have the advantage of a long proven historical track record.
Control of ice dams moisture accumulation and heat gain can be successfully addressed by both vented and unvented attic or roof design.
Roof vents are for warmer climates.
When insulating your attic the contractor can either spray the attic floor to keep a vented attic or spray the roof deck for an unvented system.
Let s dive a little deeper into what that means exactly.
The choice of the venting approach is up to the designer.
In this case you can learn a lot from foam tech s article vented vs.
Vented roofs vented roofs serve a number of different purposes and their roles vary from climate to climate.
Control construction moisture content with tenting or temporary roofing when necessary.
In pitched roof construction thermal insulation can be placed horizontally at ceiling level cold roof.