Enhanced high-performance vapor control membrane, suitable for all fiber insulation materials

Product General Information:

Commercial Terms of Products:

Description:

Vapor barriers are a type of membrane product that allows moisture to diffuse in one direction while blocking or slowing down reverse moisture transport, and their permeability increases with humidity. These  vapor barriers are designed for cold climates and are installed on the inside of wall structures to prevent warm, humid air from condensing on the back of the wall panels, while allowing the wall structure to dry from the outside in.

The problem with installing ordinary polyethylene moisture barriers in wall structures is that we are affected by the seasons. Moisture flows from the warm side of the wall structure to the cold side, from areas of higher humidity to areas of lower humidity, meaning that in summer, moisture can enter the room from the outside. The greater the temperature difference, the stronger the moisture flow. If a completely impermeable membrane is installed, this moisture will remain trapped in the wall structure for most of the year, leading to mold growth and rot. vapor barriers solve this problem by allowing moisture to flow into the room during the warmer months, preventing moisture from remaining in the wall cavities.

The concept with all of these vapor control membranes is that they can change their vapor permeance at specific relative humidity levels or saturation, comparable to wood products, with absolute humidity being the main factor that determines the direction of moisture flow (remember, moisture moves from more to less, and from warm to cold. More to less supersedes warm to cold, though they are often moving in the same direction).   

Kingway's UBW (Underlying Water) moisture barrier features vapor permeability that increases with relative humidity, allowing moisture to move towards areas with lower vapor pressure. Composed of a polypropylene mesh and a polyethylene copolymer, its inner surface maintains a low-level moisture barrier performance until indoor relative humidity exceeds 70%, at which point vapor permeability increases to 1.6 perms, allowing for controlled drying of higher humidity environments within buildings. Conversely, the outer surface of the membrane has a permeability of approximately 13 perms, allowing moisture to dry inwards during warmer months. However, UBW is not strictly a "directional" moisture barrier, as the technology relies on relative humidity and vapor pressure to promote diffusion. Therefore, this product is not suitable for spaces with consistently high humidity, such as indoor swimming pools, steam rooms, and shower rooms.

Applications:

The smart vapor control layer is always located at the interior side of the assembly prior to the insulation layers. This prevents the vapor from the interior from diffusing through the wall cavity and condensing on the backside of the cold sheathing. We don’t want the moisture from the interior stagnating within the insulation layer, as this can create moisture and mold problems.

If a  vapor control layer is to be located in the ceiling assembly, such as for a vented roof, the membrane will also be installed on the warm side of the wall, prior to the insulation layer like a wall system. However, if the smart vapor control layer is to be installed on the ceiling in isolation, it must be taped to the top plate or to the weather barrier to provide air and vapor control continuity.

You cannot use smart vapor control layers under slabs, as they allow too much moisture to pass through during moist conditions, which will be absorbed by the concrete and redistributed to other hygroscopic materials. 

Specifications:

Competitive Advantage: