Ventilated and Insulated Rain Screen Cladding (V.I.R.S.C.)
Information Based on Euro Panels Overseas Literature.
The basic section of an external wall construction composed in accordance to the VIRSC principle consists
of:
1: a load bearing structure
2: a layer of thermal insulation on the outside of the load bearing structure
3: a ventilated air gap / cavity
4: intermediate supporting structure to connect the load bearing structure and the architectural panel
5: an architectural panel
The ventilation (circulation of air) is created in the cavity by leaving an open joint at the bottom and the
top of the cladding. This principle must be followed consistently meaning e.g. that air in- and outlets
should also be designed below and above windows
PREVENTION OF INTERNAL CONDENSATION
In cold seasons the partial vapor pressure inside the heated building is higher than outside, leading to a
transport of vapor through the outside wall. This vapor could condensate in the air gap against the back
of the architectural panel but the dry air that circulates through the cavity will eliminate this moisture.
COOLING EFFECT IN THE SUMMER
A very large portion of the solar radiation energy is dispersed before it even reaches the thermal insulation
material:
- Depending on the color used, some radiation will be reflected.
- The temperature of the panel itself increases, which consumes another part of the incoming energy.
- At last, the air in the air gap is heated up, creating a chimney effect that conveys continuously fresh
outside air into the cavity, cooling down the whole construction.
NO THERMAL BRIDGES
Because the insulation is applied outside the supporting structure, this creates a continuous thermal barrier,
so that thermal bridges and their associated problems – such as surface condensation and consecutive
creation of unhealthy mould growth - are avoided.
NO RAIN REACHES THE THERMAL INSULATION OR THE LOAD-BEARING
CONSTRUCTION
The outside wall cladding functions as an umbrella, so the internal construction remains dry. Moisture
penetrating the cavity either runs down the back of the architectural panels or is removed by natural
ventilation.
LOW TEMPERATURE VARIATION IN THE LOAD-BEARING CONSTRUCTION.
Normally one tries to achieve a stable interior temperature but can not influence the exterior temperature
variations. By installing the thermal insulation material on the outside of the load bearing construction, the
biggest variation of temperature will occur inside the insulation material leaving only minor temperature
variations in the interior wall. In this way the interior structure is protected from high thermal stresses and
so the risk of cracks is reduced.
DIMENSIONAL STABILITY OF THE CLADDING MATERIAL
Because the architectural panel is ventilated both at the front and at the back, there is almost no differential
hydrothermal load working on it. This results in a stable panel behavior.
The supporting structure onto which the architectural panels are fixed can be made of:
- wood
- galvanized steel
- aluminum
- stainless steel
Article by of Foundry Service and Supplies, Inc. Foundry Service and Supplies, Inc. is a Distributor and Fabricator of high-density fiber cement board products for the Western United States for American Fiber Cement Corporation. American Fiber Cement Corporation is the Master Distributor for the United States of America for Euro Panels Overseas (manufacturer). www.foundryservice.com; www.americanfibercement.com; www.europanels.be