In construction the term “rear-ventilated facade” describes a sophisticated technique to give facades an appearance that is characterized by individuality, high quality and longevity.
The design of a rear-ventilated facade
Rear-ventilated facades are built up as followed. First, the substructure is fastened to the masonry; it serves as a static connection between the outer wall and the facade cladding. The thermal insulation is inserted between the substructures. In the next step, the facade panels are attached to the substructure.
The advantages of rear-ventilated facade are versatile
Components of insulation (heat, cold, fire protection) and cladding (weather protection) are structurally separated from each other in the system of the rear-ventilated facade. The rear ventilation area between the components controls the moisture content in the building structure: building and usage moisture are reliably dissipated there by the air stream.
After the use as a rear-ventilated facade, substructure, insulation and facade cladding can be collected separately and can be recycled. If the production of prefabricated façade panels is more than 90 % of recycled aluminium, as it is the case with Metawall®, and recyclable insulation materials are selected, the cycle of recycling and sustainability is almost perfect. A detailed ecological balance of the facade panels can be found in the environmental product declarations according to DIN EN ISO 14025 Type III and EN 15804.
In comparison to heat insulation systems (ETICS) the higher construction costs are amortized during the period of use, since the costs for cleaning and maintenance for rear-ventilated facades are lower. (see www.architektur-aktuell.at, „Die Analyse der Lebenszykluskosten spricht für die VHF“)
Damage to curtain wall facades can usually be repaired by replacing the individual elements. It is not necessary to renew the entire facade.
What are the disadvantages of the rear-ventilated facade compared to other facades?
The time required for the assembly of rear-ventilated facade is usually somewhat higher than for other facades, e.g. thermal insulation systems. The material costs are generally also higher than costs for thermal insulation composite systems. Negligible disadvantages could be mentioned like depending on the insulation thickness, the thickness of the facade is a little bit bigger and the wall where the facade will be fixed, must be sufficiently stable. Nowadays this is no longer a question because brickwork or concrete are stable enough.
Rear-ventilated facades with aluminium sandwich panels Metawall®
Stone buildings were the first truly permanent man-made buildings. With iron and steel incredible heights were achieved and aluminium, as the most modern of these three building materials, allows versatile and lightweight constructions. Of course aluminium is almost a soft building material in relation to stone and steel, but it depends on what is made of it. There are materials which, by themselves, have hardly any stability and load bearing capacity. If, however, the same materials are combined with one another in different shapes, the load capacity and stability are increased a lot.
Metawall® aluminium facade panels are such materials. The combination of two aluminium cover sheets with a corrugated aluminium core makes the light metal aluminium an extremely solid building material. Compared to a solid aluminium plate of the same thickness, Metawall® is up to 80 % lighter, but achieves the same static values.
The facade panel is not constructed as a composite material. Cover sheets and core material are made of aluminium. Therefore the entire panel is made of 100 % recyclable material, which does not have to be separated for the recycling process.
The continuous production process allows the production of exceptionally large facade elements with a plane surface, which remains dimensionally stable and flat even for large elements.
Different colours, e. g. RAL, NCS, BS, Pantone and metallic colours, can be offered. Individual colour schemes are available on request. Unlike other sandwich panels, Metawell® panels can be powder-coated (on request).
The fire behavior of the facade panels is classified according to European Standard EN 13501-1. “Metawall®” has a fire classification of B – s2, d0 (flame retardant) and “Metawall® A2″ A2 – s1, d0 (non combustible).
In order to obtain a building certification e.g. DGNB or LEED, life cycle assessments of every building product used are required. In order to simplify this and to make it more comparable, so-called environmental product declarations (EPDs) are used. For the Metawall® and Metawall® A2 facade panels, environmental product declarations according to DIN EN ISO 14025 Type III and EN 15804 are available.
Time and cost pressures are steadily increasing in construction industry. An approach to reduce costs, is designing the building in 3D before the start of construction, so that disagreements in planning can be reduced. To simplify the work of architects, structural engineers and draftsmen, the facade elements can be downloaded for ArchiCad and Revit at bimobject.