06 ventilated facades

Session 6

Ventilated Facades 5.1. Introduction 5.2. Rendered thermally insulated façades 5.2.1. Details 5.2.2. Case studies 5.3. Other systems 5.4. Blibliography

Based on the original presentations by Prof. Juan Alamillo. Adapted by Prof. Julián García julian.garciam@upm.es Translated by Luis M. Martín

06. Ventilated Faรงades

6.1. Introduction Ventilated faรงades (double skin faรงade is used for curtain glass systems) is a widely used faรงade system based on an inner strong brick layer, a rigid sheet of insulation on the outside, appropriately anchored to the support, and a stone, ceramic or metal cladding anchored to a steel substructure.

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06. Ventilated Façades

Performance A ventilated façade is a construction system that allows continuous exterior insulation for the building, protecting the interior sheet as well as the slab edges. In the ventilated chamber, due to the heating of the air layer of the intermediate space, the so called “stack effect” is produced, creating a continuous ventilation in the cavity. This ventilation helps keeping the insulation dry and lowers not only radiation but also convection energy interchanges, providing a better performance of the façade.

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6.2. Elements

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6.2.1- Inner resistant layer. Fully supported by the main structure, or part of it –load bearing walls are included.

6.2.2- Thermal insulation. Continuous and regular, non-hygroscopic, highly durable and resistant to external agents.

6.2.3- Substructure. Formed by anchoring points and horizontal and vertical sections in different combinations. Its function is to support the external panels, transmitting the loads to the main structure and / or the inner sheet.

6.2.4- Continuous air cavity. Ventilated and drained, it avoids both thermal bridges and condensation problems.

6.2.5- Outer cladding. Typically formed by pieces or panels arranged with open joints. Highly durable, with specific requirements of mechanical strength and aesthetic function.

06. Ventilated Façades

6.2.1. Inner resistant layer It is necessary to check the stability of this layer considering the eccentric load produced by the outer element. The usual standards are: - Concrete. Blocks, on site walls or prefabricated panels.

- Solid and perforated ceramic brick.

- Hollow brick (checking stability and compatibility with anchors) 6.2.2. Insulation Different fixation systems, most similar to the ones used in ETICS façades. Usual materials are: - Projected polyurethane foam (caution: fire behavior) - Fiberglass panel –non hydrophilic.

- Wool rock panel – non hydrophilic.

- Mortars with mineral fibers.

- Cellular glass plates.

- Extruded polystyrene panels (caution: fire behavior) - Expanded polystyrene panels (caution: fire behavior and water absorption) - Other insulating mortars.

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6.2.3. Substructure Individual anchors or fasteners of stainless steel (threaded or corrugated rods, with plates and bolts) are fixed to the inner layer by epoxy resin mortars or mechanical expansion systems. Bearing substructures are generally built using lightweight aluminum, galvanized or stainless steel.

6.2.4. Air cavity It is a substantial part of the ventilated faรงade system. Its usual thickness is between 3 and 6 cm, but can be dimensioned with specific programs of fluid dynamics to adjust the thickness to the desired airflow, depending on climate area, orientation, etc.

06. Ventilated Façades

6.2.5. Outer cladding The usual standards are: -Natural stone cladding.

-Ceramic tile cladding.

-High performance ceramic tile cladding.

-Fiberboard and cement-derived cladding.

-Composite panels –aluminum+resin and others.

-Aluminum, zinc or galvanized steel panels (natural or lacquered).

-Synthetic panels.

Synthetic panels. ULMA Catalogue.

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6.3. Stone cladding Stone. Resistant to external aggressions. Granite, marble and limestone are the usual standards. Spanish legislation: NTE RPC Plates. The minimum thickness of the stone cladding, for conventional anchors, shall be 30 mm. The usual commercial dimensions are 80x80 cm, 80x60 cm, 80x40 cm, 60x40 cm and 60x30 cm. The recommended gap is 5mm between pieces, both horizontally and vertically.

Anchors. 4 units per panel, 2 on the top edge and 2 on the bottom. Distance of the corners: 6 cm. The anchors should withstand the weight of the top panel and only retain the bottom panel without transmitting vertical loads -a clearance of about 2 mm will be implemented for this purpose, disposing a separating washer.

Stone cladding. ULMA Catalogue.

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Stone cladding

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Stone cladding

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Stone cladding

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Stone cladding. Case studies

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Stone cladding. Case studies

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6.3. Ceramic tile cladding A specific coating is used for ventilated facades, usually rectangular ceramic hollow tiles of extruded stoneware, sometimes colored. The pieces are designed to overlap in horizontal edges, preventing the entrance of water. Transverse edges usually have a straight cut.

The tiles are fixed using stainless steel staples to a generally upright substructure formed by studs attached to the inner layer and / or the building structure by means of adjustable supporting and retention brackets. These systems are not regulated by specific legislation need to be in possession of a Spanish DIT (Technical Approval) or ETA (European Technical Approval).

A standard Canadian ceramic tile ventilated faรงade.

The window is located near the outer layer.

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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06. Ventilated Faรงades

Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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Ceramic tile cladding. Case studies

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6.4. Other systems Other systems are: -Fiberboard and cement-derived cladding.

-Composite panels –aluminum+resin and others.

-Aluminum, zinc or galvanized steel panels (natural or lacquered).

-Synthetic panels.

Composite panels. ALUCOBOND Catalogue.

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6.4. Bibliography Deplazes, A (Ed.) (2009) Constructing Architecture. Materials, processes, structures.

Birkhäuser, Basel Herzog, T. et al (2004) Facade Construction Manual. Birkhäuser, Basel Knaack, U.; Klein, T.; Bilow, M.; Auer, T. (2007) Façades. Principles of Construction.

Birkhäuser, Basel Poirazis, H. (2004) Double Skin Façades for Office Buildings. Division of Energy and Building Design. Department of Construction and Architecture. Lund Institute of Technology. Lund University.

Reichel, A. (2007) Open-Close. Windows, Doors, Filters. Birkhäuser, Basel Spanish regulations: CTE DB HE, Ahorro de energía CTE BD SU, Seguridad de utilización CTE DB SI, Seguridad de incendio CTE DB HS, Salubridad