As your exterior walls attempt to protect the inside of your building from wind, rain and snow, an element which is often overlooked is the impact of temperature and humidity differences on performance. Conditions within a building typically vary from those outside. These temperature and pressure differentials can have potentially damaging results. As nature tries to equalize these imbalances, a couple of different scenarios occur:
When humidity differs from the inside to the outside of a building, water vapor from higher concentration areas will try to migrate to low concentration areas. When the pressure within the wall cavity is lower than the external pressure, water vapor is actually drawn in through permeable wall materials and voids which occur wherever the vapor barrier is interrupted by windows, outlets and other interfaces.
In any climate, conditions occur which cause condensation within the wall assembly. Since the temperature within the building differs from that outside, gradients occur across the wall between the two zones. The greatest temperature drop occurs in the components with the best insulating properties. If enough water vapor is present, this shift in temperature will cause the air to reach its saturation point, causing condensation to form within your wall cavity, often within the insulation.
In traditional construction, this moisture becomes trapped and begins to deteriorate masonry veneers, corrode metal components of the structural wall, cause mold and mildew formation, or find its way through to your interior, damaging interior finishes. Moisture damage to insulation greatly reduces its R-value, increasing your building’s dependence on heating and cooling systems.
Rainscreen recognizes the fact that moisture is a natural occurrence within the wall cavity. An uninterrupted, impermeable air barrier is created on the outside of the structural wall, integrated with the window panels, allowing no gaps for air and moisture flow to the interior. Veneer joints are left open to allow air to circulate within the wall cavity, keeping the insulation dry by allowing the moisture to evaporate.
Vapor barrier is interrupted at floor and window lines, outlets, etc. Adequate wall cavity air flow and drainage is not provided. Wall interior is inaccessible.
Air barrier is continuous and integrated with window systems. Air flow allows for evaporation of moisture. Separate panels allow easy access if needed.
W.J. Higgins & Associates provides innovative solutions to improve wall health and longevity. Combining the latest technological developments with the same principles that have helped European architects create elegant and enduring structures through the centuries, the W.J. Higgins team uses a refined European rainscreen technology that can stand up to even the harshest climates found in the United States. “Open-joint, back-ventilated, pressure-equalized” rainscreen technology allows adequate air circulation so wall cavities remain dry, insulated and corrosion free – an approach that has provided a 100% success rate.
With the exterior veneer no longer filling the role of air barrier, new horizons for design are possible, with results everyone can appreciate:
ARCHITECTS enjoy the aesthetic benefits of greater design flexibility. Window and wall veneers require no caulking, resulting in cleaner design lines. By eliminating the need for sealants, panels never develop unsightly leaching around edges as caulking weathers.
BUILDING OWNERS will appreciate the fact that facades require reduced washing and have no sealants to replace, a substantial maintenance cost associated with a traditional construction process. The use of rainscreen not only eliminates corrosion within the wall, but optimizes the effect of the insulation, enhancing its R-value and reducing the dependence on heating and cooling systems.
CONTRACTORS find that rainscreen can give them scheduling freedom not available with traditional methods, since construction can proceed on interior walls before the engineered veneer is in place.