01 traditional facades

Session 1

Traditional Façades 1.1. Elements 1.2. A bit of history 1.3. Multiple layers 1.4. Insulations 1.5. The evolution of the contemporary façade and its thermal performance 1.6. An analysis of a multiple layer insulated wall 1.7. Spanish regulations. CTE requirements 1.8. Blibliography

Based on the original presentations by Prof. Luis Beltrán - luisfelipe.beltran@upm.es Adapted by Prof. Julián García Translated by Luis M. Martín

01. Traditional Façades

1.1. Elements Here’a a list of the main elements that can be found in what we’re going to call a “traditional brick façade”, the way they’re still built in Spain.

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Hollow brick wall Insulation Cavity Concrete Slab Weather cladding Fiber mesh Perforated brick wall Steel strip Lintel steel section Timber jamb Timber window Concrete sill Waterproof layer Perforated brick wall Cement dressing

Rigid Insulation Steel Plate Steel bracing Lintel steel section

01. Traditional Faรงades

1.2. A bit of history Good old solid walls were made out of one thick layer of mud, brick or stone. Resistance was guaranteed, as their thickness was always over 50 cm. They were also, although not exactly waterproofing, quite good at avoiding humidity, but not so good at insulating the interior of the building: a 100 cm. thick brick wall is only equivalent to a multiple layer faรงade with cavity, but without insulation.

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01. Traditional Faรงades

That said, it is important to emphasize their thermal inertia is quite high, what makes them an appropiate solution to keep the building fresh during the summer.

These walls were covered with all sorts of claddings: stone, ceramic tiles, mortars, etc. When they were built with bricks, all sorts of bonds were possible, as shown in the images aside.

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01. Traditional Faรงades

1.3. Multiple layers Although since ancient times examples of multiple layer faรงades (with improvements regarding waterproofing, or insulation) can be traced, facades of two separated stone or brick layers were not usual until the late nineteenth century.

In the UK, a facade system called "Cavity wall" was developed to enhance thermal insulation and prevent water from entering the interior.

The inner cavity was ventilated and drained to the outside through holes in the joints and perpends of the brickwork.

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01. Traditional Façades

The spreading of this technique occurs during the reconstruction of Europe after World War II. In Spain the idea of Cavity wall was applied in what was called “tabique pluvial” (rain wall) used in areas of high rainfall.

As an evolution of these cavity walls, several kinds of two layers wall were developed. The usual standard included 12 cm. of perforated brick, a 5-7 cm. cavity and a hollow brick partition wall.

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“Tabique pluvial”

Two brick layers without insulation

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01. Traditional Faรงades

1.4. Insulations When insulation appeared, new goals could be achieved. Insulation materials have low thermal conductivity. The most common ones in Spain are: Glass fiber. GF. Increasingly obsolete by occupational health problems (mainly workers that manipulate it). It is hydrophilic.

Mineral and rock wool. RW. Easy to install, very effective and smooth to his handlers. It is hydrophilic Expanded polystyrene. EPS. Rigid plate with tongue and groove joints, very effective, but require careful placement to avoid leaving uninsulated voids. Reproductive health problems.

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Rock wool

Expanded Polystyrene

01. Traditional Façades

Expanded polyurethane. PUR. Applied by spraying onto the façade, it guarantees its extension over the entire surface and the sealing of the walls in joints with openings. It has a low thermal conductivity, and it is waterproof, performing as an air barrier, vapour barrier, and sealing. It deteriorates with light. It presents one main problem: when temperature rises to "smoke point“, gives off toxic hydrogen cyanide gases .

Cellulose fiber. CF. Cellulose fiber mixed with glues and projected over the inner face of the façade. It is very effective.

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Projected polyurethane.

Celulose projection

01. Traditional Faรงades

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01. Traditional Faรงades

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1.5. The evolution of the contemporary faรงade and its thermal performance Faรงade type

Northern Europe

Spain

Traditional solid wall

Prior XXth century

Prior 1950

4 w/m2 K

Cavity wall

1945

1950

1,5 a 2 w/m2K

Wall-cavity1973 Oil Crisis light insulationhollow brick wall Wall-cavitystrong insulationhollow b. wall

1997 Kioto Protocol

Spanish Legislation

Thermal Transmittance

1973

NBE CT 79

0,5 a 0,8 w/m2K

2004

CTE DB HE 2004

0,2 a 0,4 w/m2K

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01. Traditional Faรงades

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1.6. An analysis of a multiple layer insulated wall Multiple layer facades with insulation are the most common facades in Spain.

Structural performance. In what comes to structural performance, the main layer of the faรงade is restricted by two floors. A height less than 2.80 m. (the average height) is sufficient to withstand wind actions and physical attacks due to regular use. Wind pressure on urban situation, and up to 10 storeys high, can reach 0.8 kN/m2, and suction about 0.4 kN/m2. That means the main layer will form an arch to carry the horizontal loads to the floors. Support must therefore be of at least 6 cm.

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Wind pressure and suction. Models by J.L. De Miguel

01. Traditional Faรงades

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Waterproofing, if assigned to the outer brick wall, is not guaranteed, as ceramic brick is not sufficiently watertight under medium and high rainfall, so it will require the help of any of the following elements: Dubbing out the inner layer, adding outer cladding, designing drainage systems or using a watertight material as insulation.

Photo:LB

Photo:LB

Photo:LB

01. Traditional Faรงades

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Insulation. Problems with insulation, in this system, come through thermal bridges, which are usual in openings and floor contacts.

In what comes to sealing, the wall is sufficiently airtight, so no specific air barrier is required. Condensation problems might appear, so on the warm side of the insulation a waterproof layer will be necessary. A common solution is a 0.2 mm thick layer, or laminated paper attached to the rock wool insulation. Closed cell insulations, such as PUR or EPS, are also an option.

Vapour barriers. Polyurethane, paper, polyethylene

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01. Traditional Faรงades

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1.7. Spanish regulations.

CTE requirements CTE DB HS1. Examples

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01. Traditional Faรงades

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Spanish regulations.

CTE requirements CTE DB HS1. Examples

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Ejemplo de encuentro fachada con forjado

01. Traditional Faรงades

Spanish regulations.

CTE requirements CTE DB HS1. Examples

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01. Traditional Faรงades

Spanish regulations.

CTE requirements CTE DB HE Catalogue of constructive elements.

(U= Thermal transmittance)

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01. Traditional Façades

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1.8. 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