01 traditional facades

Session 1Traditional Façades

1.1. Elements1.2. A bit of history1.3. Multiple layers1.4. Insulations1.5. The evolution of the contemporary façade and its thermal performance1.6. An analysis of a multiple layer insulated wall1.7. Spanish regulations. CTE requirements1.8. Blibliography

Based on the original presentations by Prof. Luis Beltrán - [email protected]

Adapted by Prof. Julián GarcíaTranslated by Luis M. Martín

mailto:[email protected]

01. Traditional Façades p.01

1.1. ElementsHere’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.

Hollow brick wallInsulation

CavityConcrete Slab

Weather claddingFiber mesh

Perforated brick wallSteel strip

Lintel steel sectionTimber jamb

Timber window

Concrete sillWaterproof layer

Perforated brick wallCement dressing

Rigid InsulationSteel Plate

Steel bracingLintel steel section


1.2. A bit of historyGood 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 façade with cavity, but without insulation.


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.


1.3. Multiple layersAlthough since ancient times examples of multiple layer façades (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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“Tabique pluvial”

Two brick layers without insulation


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.

Rock wool

Expanded Polystyrene


1.4. InsulationsWhen 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.

Projected polyurethane.

Celulose projection


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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Façade type Northern Europe

Spain SpanishLegislation

Thermal Transmittance

Traditional solid wall

Prior XXth century

Prior 1950 4 w/m2 K

Cavity wall 1945 1950 1,5 a 2 w/m2K

Wall-cavity- light insulation-

hollow brick wall

1973 Oil Crisis 1973 NBE CT 79 0,5 a 0,8 w/m2K

Wall-cavity- strong

insulation- hollow b. wall

1997 Kioto Protocol

2004 CTE DB HE2004

0,2 a 0,4 w/m2K


1.5. The evolution of the contemporary façade and its thermal performance

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


1.6. An analysis of a multiple layer insulated wallMultiple layer facades with insulation are the most common facades in Spain. Structural performance. In what comes to structural performance, the main layer of the façade 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.

Photo:LB


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

.Vapour barriers. Polyurethane, paper, polyethylene


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.

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1.7. Spanish regulations. CTE requirements

CTE DB HS1. Examples

.Ejemplo de encuentro fachada con forjado


Spanish regulations. CTE requirementsCTE DB HS1. Examples


Spanish regulations. CTE requirementsCTE DB HS1. Examples


Spanish regulations. CTE requirementsCTE DB HE

Catalogue of constructive elements.(U= Thermal transmittance)


1.8. Bibliography

Deplazes, A (Ed.) (2009) Constructing Architecture. Materials, processes, structures. Birkhäuser, BaselHerzog, T. et al (2004) Facade Construction Manual. Birkhäuser, BaselKnaack, U.; Klein, T.; Bilow, M.; Auer, T. (2007) Façades. Principles of Construction. Birkhäuser, BaselPoirazis, 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 energíaCTE BD SU, Seguridad de utilizaciónCTE DB SI, Seguridad de incendioCTE DB HS, Salubridad

01 traditional facades

Documents

traditional brick faade

thick brick wall

hollow brick partition

layers wall

cavity walls

thermal insulation

traditional faades1

idea of cavity wall