memerase.
Moisture, Permeability and Mold.
Moisture Elimination
Successful use of vinyl wallcovering requires building walls that are not subject to moisture accumulation. One of the characteristics of conventional vinyl wallcovering is that it has little or no moisture permeability. This characteristic is an important benefit in terms of durability, cleanability and wall protection, including protecting the wall from moisture penetration. However, if deficiencies in the design, construction or maintenance of a building, or other circumstances, allow liquid or vapor moisture to accumulate in a wall or wall cavity, vinyl wallcovering can act as a vapor barrier restricting the escape of moisture and increasing the risk of mold growth and other building damage from trapped moisture.
There are many possible building deficiencies that can lead to moisture accumulation in a wall or wall cavity including unsealed building exteriors (roof, walls, windows, etc.); inadequate or unbalanced HVAC systems (including failure to maintain positive pressure in a building); absence, inadequacy or misplacement of an exterior wall cavity vapor barrier; use of wet construction materials, leaking pipes, etc. Depending on the condition of a building, moisture accumulation can be more likely in hot humid climates such as the southern coastal region in the United States. If the source of the moisture accumulation is not corrected, mold growth and other building damage are likely to occur.
Good design, construction and maintenance practices can prevent moisture accumulation. In all cases, moisture and sources of moisture accumulation must be corrected before installing any wallcovering. Mold inhibitors contained in vinyl, adhesives, and primers used for wallcovering will not prevent mold growth if moisture is allowed to accumulate in a wall or wall cavity. Prompt corrective action to eliminate moisture accumulation is always required.
Increased Permeability and Permeability Testing
The permeability of conventional vinyl wallcovering can be increased by perforation. If vinyl wallcovering is given high quality perforation, is properly installed on a permeable wall surface and properly maintained it will have greater permeability than conventional vinyl wallcovering which has not been perforated.
While offering increased permeability, perforated wallcovering is not a solution for and should not be used in buildings which have or may have wall cavity moisture accumulation or other moisture problems. Perforated wallcovering will not prevent mold growth or other moisture related damage if moisture accumulation is permitted to occur in a wall or wall cavity. For more information on increased permeability see Perforated Wallcovering.
Permeability is a measure of the amount of water vapor (moisture) that can pass through a specified material in a certain amount of time. The measure and degree of permeability is expressed in units referred to as Perms. Materials with high Perm levels will allow more moisture or water vapor to pass through than those with lower Perm values. For more information on permeability see Permeability, Permeability Testing and Perm Ratings.
Wallcovering Selection and Maintenance
It is important to keep in mind that wallcovering is a building material and is one component of a building's integrated wall system (which includes exterior wall surface, sheathing, exterior wall cavity vapor barriers, insulation, framing, HVAC and interior wall substrate, among other materials). Prior to using any wallcovering an experienced building professional (who is familiar with the specific building, local conditions and the characteristics of vinyl wallcovering) must be consulted to determine, in light of wall and building conditions, permeability requirements, and other building specific requirements, which wall surfacing materials are appropriate for that building.
All wallcoverings must be installed by an experienced commercial wallcovering installation professional who understands wallcovering use and installation requirements, including the requirement to test for and eliminate sources of moisture accumulation prior to the installation of wallcovering.
Building maintenance must include those actions necessary to prevent the development of moisture accumulation sources as well as routine inspections for and immediate corrective action if moisture accumulation is found in a wall or wall cavity.
Learn more about the basics of wallcovering selection, use, installation and maintenance.