High-Density Fiber Cement Boards on a Rain-Screen System

                                         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

• Foundry Service's blog
• Login or register to post comments
• Printer-friendly version
• Send to friend