Product overview

Bricks are fired from natural raw materials such as loam, clay and clayey masses at temperatures of more than 1,000°C. The power of fire transforms the earth into ceramic shards and strengthens the unique properties of the brick. The uniqueness of bricks is the transformation of natural raw materials during ceramic firing, in which all material components are baked permanently together. This turns the brick into a solid ceramic material with a capillary pore structure. This structure is unique and guarantees the excellent moisture behaviour of brick products and the proven brick living climate. While other building blocks are usually calculated on the basis of a limited useful life, the service life of facing bricks and clinker is very high and measured in millennia. Insurance companies calculate the service life of buildings at 100 years. Buildings with facing brickwork, however, remain stable for a long time afterwards. There are examples of brick architecture that is more than 1,000 years old all over the world.

Facing bricks are available in an amazing variety of colours. The variety of natural clay deposits, modern firing technology with temperatures of around 1,000°C, but also the traditional art of firing, tradition and experience of the bricklayers form the basis of the colour palette. Just as important are the many scientific studies on the effects of temperature on clay and the reaction of the natural components contained in the raw material during the firing process. But the interaction of the many chemical and physical influencing factors during firing leaves a lot of room for coincidences. The ceramic material as well as modern production and surface designs allow unlimited colour variations and shades, and bring natural colour and fascinating charisma to the façade. Even natural red brick façades have always fascinated with their charmingly iridescent play of colours. The reason lies in the essence of ceramics: minor irregularities in surface structure and colour are part of the facing bricks’ natural building material, as are the colour scheme and grain of wood’s optical characteristics. Five basic types of different colour designs characterise facing bricks – natural-coloured, continuously coloured, engobed, glazed and steamed facing bricks. Even the natural red firing colour, which results solely from natural raw materials and their specific firing temperatures, encompasses a broad spectrum of natural red colours. A steamed facing brick has a greyish-blue-silvery colour, which is caused by an oxygen-reduced firing. An otherwise red firing brick develops into a grey- to anthracite-coloured facing brick. Brick façades retain their aesthetic appeal throughout their service life. Brick products are the only artificially produced building block whose colour does not fade or change with age. This is due to the fact that the brick is manufactured exclusively from natural raw materials and without binding agents. Whereas in the case of other building blocks, the binder is decisive for the strength of the grain structure, with clay bricks this is due to the high firing temperature in the kiln. The disadvantage of building materials containing binding agents is that the binding agent (lime, cement) loses all or part of its original properties over time under the influence of environmental influences. The mostly artificially produced colour tones, such as those used in coloured concrete blocks, for example, are bleached over time under the influence of acid rain and because of the low UV resistance.

The almost unlimited variety of colours and structures of the bricks offers architects and building owners a great deal of scope for façade design. The bricks in exposed masonry have the special characteristic of functioning as the smallest unit of a measurement system in a grid. Nevertheless, they appeal to the human senses through their colourfulness and richness of shading, their visual accessibility, through the tactility of the surface and above all through the possibility of implementing almost every artistic intention into practice using shaped bricks. The small-format bricks combine extremely contradictory building ideas: oldest and newest, rationality and romance, manageability and monumentality, standardisation and artistically free design. The facing brick in the façade is a valuable, proven and authentic building material. The optical effect of brick façades largely depends on the colours used. Dark bricks appear more solid and visually reduce the height of the building, while light bricks achieve the opposite effect. The surface texture usually depends on the type of raw material, the manufacturing process and the surface treatment. The colour of a brick is complemented by its surface structure. Brick surfaces can be structured by different profiling processes. The surface treatment of extruded bricks includes the mechanical treatment of the visible surfaces by grained rollers and rotating steel wire brushes, the peeling of the smooth press skin and the action of wedge-shaped mandrels, which are guided over the visible surfaces by templates to produce wavy grooves. The format is the basis for the scale and proportions of a brick façade. It shapes the optical effect and forces the architect to order the design of his building. For example, a façade consisting of small-format bricks appears lively, while large formats convey a calmer façade image. The joint has a constructive significance as a link between the individual elements and also plays an important role as a design element. The overall appearance of the façade can be decisively influenced by the choice of joint structure and the mortar colour. A deeply recessed joint, for example, reinforces the effect of light and shadow by casting dark shadows. Joints that are flush with the surface of the masonry do not cast a shadow, but instead emphasize the entire surface of the wall.

High maintenance is about more than just the costs in time and money. It is also a burden on the environment. Therefore, maintenance costs are an important criterion for the environmental friendliness of an exterior wall. Brick façades do not require plaster systems or protective coatings against fungi, algae and frost. Burnt clay is practically rot-proof, as demonstrated by Assyrian clay tablets and, to an even greater extent, by historical exposed masonry, which has not been affected by acid rain in recent decades. The worktops and floors in chemical laboratories are made of fired clay, as are the beds of sewer channels. Buildings in northern Germany with the highest driving rain load are preferably constructed with visible brickwork. The maintenance-free nature of brick façades is down to the physical properties of the ceramic shards. Due to their high compressive strength, the facing bricks in exposed masonry are insensitive to mechanical influences. Due to their relatively dense surface, the facing bricks have a self-cleaning effect: dirt particles in the atmosphere cannot penetrate into the surface and are quickly washed off by rain. Anyone taking a closer look at the beautiful brick façades of the post office, railway and other buildings in the new federal states (in the former East Germany) at the beginning of the nineties and comparing them with the adjacent façades, will surely also appreciate the value of even older brick façades, especially in view of the 50 years of almost non-existent façade care.

Real estate is only a reliable contribution to a retirement provision if it maintains its value. Houses made of brick façades are permanently insensitive to weather influences and completely maintenance-free. The solid structure of a brick façade guarantees a long service life. This is clearly reflected in the resale value. Houses with double-shell facing brickwork have a high market and image value, which gives them a higher sale or rental price. The argument of 80-year freedom from maintenance is particularly convincing to buyers. A high resale value is thus important. A house should appeal to as many buyers as possible. A robust building fabric, market-driven architecture and family-friendly floor plans promote sales. For many people embarking on building projects, owning their own home means entering the world of capital accumulation, an additional old-age pension, but unfortunately often also a high level of long-term debt. In most cases, builders finance their new home through a combination of equity and credit. In the case of external financing, the lending limit decides on the granting of mortgages. As a rule, banks or savings banks ensure that the repayment of loans is guaranteed even under unfavourable circumstances. In the case of a low borrower contribution, the lending limit can decide whether the construction project is feasible. The lending limit depends on how high the lenders assess the risk. With a solidly built house constructed using double-shell facing brickwork, you are also ahead when it comes to external financing. The value stability of a home made of brick also ensures a high lending limit.

Experimental investigations carried out by the Fraunhofer Institute for Building Physics on the influence of the absorption of solar radiation on the transmission heat losses of exterior walls made of brickwork have shown that solar effects lead to a reduction in the transmission heat losses of non-transparent exterior components such as brickwork, which depends on the degree of radiation absorption and is independent of the heat transfer coefficient. However, the amount of the saving is basically dependent on the irradiation and thus on the orientation, on the climatic boundary conditions and on the turbidity of the air. The amount of the percentage savings, which show a relatively large, unavoidable measurement uncertainty, depends on the degree of absorption of the surface of the available irradiation and the mean air temperature difference. The results of this and other research work on this subject have been summarised by the Working Group on Bricks in a report as follows: The consideration of solar absorption on opaque component surfaces with the associated energy gains over a long period of time has received little attention in the evaluation procedures for determining the thermal requirements of buildings. However, the new European standards for calculating the heating requirements of buildings currently make it possible to take these solar effects into account, which can have a positive effect on the associated verification procedure. Simulation calculations have shown that using bright, i.e. plastered, single-shell exterior walls can save 1.5 to 4.5 percent of heating heat through solar absorption. For dark surfaces, these values are between two and around eight percent energy savings. This bonus is largely independent of the single or double shell design. However, heavy exterior walls show higher improvement values than light walls such as highly insulated wooden stud constructions. The summary of the evaluation of the research work of different authors leads to the conclusion that solar absorption on exterior walls can lead to significant heat savings. With highly absorbent surfaces such as dark facing brick and clinker brick walls, the highest improvement values of up to 26 percent can be achieved on south-facing walls. Due to the small proportion of the total loss accounted for by exterior walls, the reduction in the heating requirement of average buildings is only of minor significance. In practice, around two to eight percent heat savings are possible in unshaded façades.

The thermal insulation properties of a building component reduce the heat transfer from the warm to the cold side. For example, good thermal insulation of the exterior components reduces the heating energy requirement of a building. In addition, good thermal insulation reduces daytime-, weather- or usage-related temperature fluctuations, which contributes to improving the comfort of the room climate. The chronological sequence of the process of heat storage is illustrated by the example of a brick facing: When the sun shines on a facing, it heats up gradually. The highest temperature only occurs at the back of the facing when it has already abated again on the outside. This phase shift means that part of the radiated heat does not penetrate further inwards after the maximum outside temperature has dropped, but flows back to the already-cooled outside. Therefore, the temperatures on the outer surface of an exterior wall fluctuate far more than on the inner surface. As a rule of thumb, the heavier a material, the better it can store heat. Due to the effect of the brick facing shell, double-shell exterior walls are not only good at storing heat, but also heat-insulating. The excellent phase shift with solid brick facing shells contributes to the fact that the surface temperature of the façade cannot cool down significantly. Even under unfavourable macroclimatic conditions such as permanent humidity or low sunlight due to shadow, the brick facings in northern Germany and coastal regions have proven to be particularly resistant and insensitive to weather influences or algae infestation over many centuries. In contrast, external thermal insulation composite systems, where the plaster layer is only a few millimetres thick, are particularly susceptible to algae growth. The low heat storage capacity of the plaster layer causes heat radiation on clear nights and thus a lowering of the surface temperature, which can always lead to harmful condensation as soon as it falls below the dew point temperature of the ambient air. Algae can chemically and physically alter the façade surfaces. It would therefore not be correct to speak of algae growth only as an optical deficiency. An algae infestation changes the moisture concentration on the component surface. Algae on façade surfaces are moisture indicators that have an inhibitory effect on moisture evaporation. The consequence of this is not only an increase in the risk of frost and the subsequent decay of the building substance on the building surface, but also rapid soiling of the façade as a result of the deposition of dirt and dust particles on the damp façade surface. This leads to a shortening of the time intervals between repair measures on the façade surface. To sum up: Storage-capable components lead to increased comfort of the room climate inside the building with continuous room use (reason: small fluctuations of the room air temperatures, lower temperature peaks in summer, slower temperature drop in case of failure of the heating). The storage of solar energy entering through windows during the transition period and in winter has a positive effect on the energetic behaviour of buildings. Storage masses in permanently used rooms allow heating with inert heating systems. Heat-storing building components are not recommended for buildings that are only used occasionally (warehouses, places of assembly). If these buildings are of lightweight construction, they can be heated quickly with the help of rapidly adjustable heating systems, so that they can cool down just as quickly after use.

The double-shell exterior wall with facing brickwork is a proven wall construction standardised in DIN 1053-1. It is recommended in DIN 4108-3 for areas with a high driving rain load (load III). This wall construction offers excellent thermal insulation in addition to the physical benefits to the building in terms of moisture and sound insulation that have been known for decades. By varying the thickness and type of building material for the bricks of the load-bearing inner shell and the thermal insulation in the hollow layer, any thermal insulation level can be easily achieved. In this respect, the double-shell exterior wall has been increasingly preferred in recent years for the realisation of particularly energy-efficient houses such as low-energy houses, passive houses, 3-litre houses and KfW 40 and 60. With the introduction of the Energy Saving Ordinance (EnEV), the heating energy requirement of new buildings is to be reduced by approx. 30 percent compared to the previous requirements. What was previously regarded as the low-energy house standard is now becoming the norm. The trend towards a double-shell design, which has been continuing for several years, will receive new impetus with the introduction of the EnEV. As the only exterior wall construction with a hundred-year success story, the double-shell exterior wall with a physically proven construction principle meets today’s requirements of the EnEV and passive houses without any problems. Double-shell facing brickwork is particularly suitable for passive houses where a very well insulated building envelope is required. The heat transfer coefficient U-value = 0.15 W/m² K required for the exterior walls of passive houses is not only achieved with this wall construction, but is also significantly undercut. Example: For wall constructions with 1.5 cm inner plastering, 24 cm load-bearing inner shell made of porous bricks, 20 cm mineral wool, 10.5 cm facing brickwork, the U-value = 0.11 W/m² K. Considering all relevant aspects for the choice of an exterior wall construction, such as economy, sustainability and individual design variety, double-shell facing brickwork will also maintain and further expand its dominant position in the market for energy-efficient houses in northern Germany in the future.

The decisive factor for the excellent resistance of double-shell exterior walls to extreme weather conditions in coastal areas is primarily the use of binder-free bricks in the facing shell. Due to their natural raw material composition, the facing bricks exhibit particularly favourable hygric properties. Bricks have the lowest equilibrium moisture content of all building materials (1.5 vol. %). This has a positive effect on the shrinkage and swelling behaviour of facing masonry. The length changes and deformations of the brick facing shells are the smallest compared to other building materials. This is also noticeable in the detailed design planning in such a way that the distance between the vertical expansion joints in the cladding can be considerably larger (about twice as large) than with other bricks such as sand-lime and concrete blocks. Basically, untreated masonry bricks containing binding agents, such as concrete or sand-lime bricks in the facing shell of the double-shell exterior walls, have not yet proven to be durable and of stable value. They are susceptible to dirt, not colour-fast and require regular maintenance just like plaster façades. Due to its particularly favourable physical properties, a double-shell exterior wall with facing brickwork is classified in the highest stress group III according to DIN 4108 Part 3 with rainfall of over 800 millimetres per year. The brick facing shell has excellent capillarity and is open to diffusion. The diffusion resistance number of the facing bricks is between five and ten, for clinker between 50 and 100. Due to the capillarity of the facing shell, a double-shell wall built according to DIN 4108-3 is one of the components for which no calculated condensation certification is required. And this applies regardless of whether the wall is designed as core insulation or with an air layer and insulation. Penetration of rainwater into the wall is mainly caused by the wind pressure and the capillary effect of the bricks. However, the most important driving force for the penetration of rainwater into building materials in northern Germany is the wind force, which presses the water into the pores of the building material surface. Until the completion of the facing shell, it must be expected that the inner shell will be completely moistened at times. Building materials with the extremely fine continuous capillaries, such as bricks, on the other hand, have a high capillary conductivity, which enables the component to dry out quickly. The moisture content of such building materials drops relatively quickly, as the water from the brick is transported to the surface as a result of capillary reaction and can evaporate there. For this reason, in walls made of bricks, the moisture sinks fairly evenly over the entire wall cross-section. The formation of a damp core inside the masonry does not occur at all. In terms of its drying behaviour, sand-lime brick lies between these two building materials.

Noise protection in buildings is of great importance for health and well-being. DIN 4109 “Sound insulation in building construction” defines the requirements for sound insulation with the aim of protecting people in recreation rooms from unacceptable nuisances caused by sound transmission. The sound insulation of a component depends primarily on the mass per unit area. For the calculation of the mass per unit area of masonry walls, wall gross densities are given in DIN 4109 as a function of the bricks used and the gross density of the masonry mortar. In the case of double-shell exterior walls built to DIN 1053-1 specifications with or without air layer, the weighted sound insulation index R'w,R may be determined from the sum of the surface-related masses of both shells, as in the case of single-shell masonry with bend-resistant walls. The value determined in this way may be increased by five decibels, as the air layer or insulation layer between the shells provides additional sound insulation. The additional value may even be eight decibels if the area-related mass of the partition walls adjacent to the inner shell of the exterior wall is greater than 50 percent of the area-related mass of the inner shell of the exterior wall. The characteristics of the double-shell exterior wall described above mean that this wall construction always achieves considerably better sound insulation values than single-shell walls. Double-shell exterior walls achieve rated sound insulation values R'w of 55 to 60 decibels and above. The reason for this is the multi-layer structure: This works like a mass-spring system. Solid shells of varying thickness and weight break the sound waves and prevent resonances. The effective separation by means of an air layer and/or insulation is important. Although wire anchors and support systems limit the overall sound insulation, they do not hinder the advantages of the double-shell sound insulation system. With double-shell exterior walls, not only the minimum requirements for sound insulation according to DIN 4109, but also the increased requirements according to Supplement 2 can be easily met.

The brick has already gone through fire for the builder. Walls made of bricks meet the requirements of DIN 4102 for fire resistance class F 90 “fire-resistant”. Bricks do not release toxic fumes and do not burn. On the contrary, they hinder the spread of fire. Bricks deliver the basic prerequisites for maximum safety. One of the most important criteria for the assessment of building materials is their behaviour in the event of fire. The fire protection classification of building materials has long been based on DIN 4102-1, which distinguishes between non-burning (building material class A) and burning building materials (building material class B). Classification into building material classes is carried out either with standardised fire tests in accordance with DIN 4102-1 or, in the case of building materials that have proven their worth, with a classification in accordance with DIN 4102-4. Building materials, e.g. steel, stone, wood, insulating materials, are classified according to their fire behaviour. Facing bricks and clinker bricks are non-combustible and are rated as classified building materials of building material class A1. Classification into Euroclasses is carried out via the test procedures laid down by the European Commission or, in the case of proven, non-combustible building products of Euroclass A1, via Decision 2000/605/EC. In the case of double-shell exterior walls, only the load-bearing inner shell is assessed in terms of fire protection. The outer, non-load-bearing facing shell protects the inner shell from external fire stresses and may be applied like a plaster layer in accordance with DIN 4102-4, Section 4.5.2.10. The values for plastered brickwork may therefore be used for the load-bearing shell of double-shell exterior walls plastered on the inside. The plaster is only required on the room side, but not between the shells.

Dynamic profitability calculations (80 years, four percent real interest) show that double-shell exterior walls with facing brickwork require approximately the same cash values as single-shell masonry walls with ETICS, i.e. they cost the same in the long term. In this respect, it is completely wrong to neglect the later maintenance costs in terms of investment costs. It was also found that increasing thermal insulation leads to economic benefits for the double-shell wall, because for U = 0.3 W/m²K, for example, ten centimetres of additional thermal insulation are not required. Façades with ETICS with 17.5 centimetres of brick backing and bricks with a density of 1.2 kg/m³ are a few centimetres slimmer than double-shell walls with core insulation, but also offer low noise insulation. Even with 24 centimetres of brick backing, this is not as good as with double-shell walls with 17.5 centimetres of inner shell, which are then approximately as thick as the ETICS walls. No other wall construction is as stable in value or as robust. A double-shell wall with facing brickwork is maintenance and repair-free for a lifetime. Dirt particles cannot settle on the masonry surface and are washed off by rain. The additional costs for a double-shell exterior wall with facing brickwork compared to a façade with thermal insulation composite systems are amortized at the latest when the plaster façade is renewed for the first time. Due to their very low maintenance costs, double-shell exterior walls with facing brickwork are usually even cheaper in the long term than external thermal insulation composite systems.

Those who build today are shaping the environment of tomorrow, its possible beauty and harmony. However, they can also create burdens that can have a damaging effect for a long time. Construction must therefore be planned in such a way that our world is burdened as little as possible. Ecological aspects: The raw material for bricks comes from the soil of our environment and is processed today in modern plants that are equally environmentally friendly and diligent. Bricks do not emit any harmful dust particles, fibres or gases. If the building is demolished later, there will be no problems with material separation. Monolithic brick walls are easy to dispose of and the brick material is even recyclable. Houses with double-shell facing brickwork are characterised by a long service life and low maintenance costs. So from an ecological point of view too, this is preferable to products with a shorter service life. In an ecological building material guide published by the Landesinstitut für Bauwesen und angewandte Bauforschung NRW, the double-shell exterior wall is classified as ecologically recommendable to highly recommendable. On the other hand, exterior walls with ETICS for new buildings are rated as ecologically not recommendable. The longer the life of a house, the better for the environment. But at some point, the time comes for every house: the house must be demolished. Mineral building materials are not hazardous waste.

The reason that using bricks as a weather protection layer reduces the risk of algae growth lies in the greater heat storage capacity of the ceramic building material, which counteracts cooling by means of long-wave radiation. Since no condensation forms on the wall surface, the risk of algae formation is reduced. The current explosive nature of this topic has been documented by the 4th Dahlberg Colloquium “Algae and Fungi on Façades II” (8/9 May 2003). Nowadays, tenants and owners no longer accept algae-infested façade surfaces without complaint. This is a trend that is also being observed by housing associations, who have been losing tenants due to unsightly façades. The only solution so far to prevent algae and fungi on ETICS systems is hardly accepted by the public due to increased environmental awareness: this is because the most common method is to add algicides and fungicides – i.e. poisons – to the layers of plaster and paint. However, biocides can only be effective if they have a certain solubility, otherwise they are not absorbed by the microorganisms. The longevity of this measure is thus limited by the necessary washing processes. Planners, but also building contractors, are required to point out the danger or risk of contamination by algae and fungi to the client from the outset when using full thermal insulation. The tasks of an exterior wall construction consist not only in providing structural thermal insulation, but also in protecting the building envelope against damage from climate-induced moisture effects, thermal stress and in creating a thermally comfortable room climate for the residents. When selecting or determining the external wall construction, structural, physical and economic aspects must therefore be harmonised. The latest findings with algae formation on highly thermally insulated façades with external thermal insulation composite systems confirm the long-established thesis that construction methods are only durable if they are adapted to the regional climatic loading. The average relative humidity in northern Germany of around 85 percent on 100 to 150 days a year represents extremely favourable conditions for the growth of algae on façades made of external thermal insulation composite systems. With the increase in algae formation on façades using external thermal insulation composite systems, it has become clear that the implementation of this construction method is only practicable up to a certain insulation thickness. That is, unless the regular cleaning and painting costs of the plaster are already taken into account during the planning stage. The known results regarding algae on façades made using external thermal insulation composite systems are further proof that it is wrong to base the calculation for the construction of new buildings only on the production costs and not on the maintenance costs incurred. As a building material in exposed masonry, brick has proven itself over centuries to be resistant and durable to extreme weather influences, such as in coastal areas. Double-shell exterior walls with brick facing brickwork are also a good alternative for the choice of external wall construction for particularly energy-efficient houses such as passive houses. They meet the requirements of passive houses with regard to a very low U-value and at the same time offer the benefits of brick façades that have been tried and tested in northern Germany for decades. Considering all relevant aspects for the choice of an exterior wall construction, such as economy, sustainability, design diversity and building physics, double-shell exterior walls with brick facing will also play a dominant role in the particularly modern energy-saving houses of the future. Facing bricks and clinkers fired at over 1,000°C in the facing shell are a guarantee that no algae can settle on the surfaces of highly thermally insulated double-shell exterior walls.

If you choose a house consisting of double-shell facing brickwork, you can rely on the fact that a permanently comfortable and healthy indoor climate is guaranteed. In particular, a load-bearing inner shell made of thermal insulation bricks is the quickest way to achieve dry rooms after completion of the building, one factor that is regarded as a prerequisite for a healthy and comfortable indoor climate. While brick facing shells ensure that the load-bearing inner shell is permanently protected from the effects of rain, frost and heat, a load-bearing inner shell made of bricks contributes to the fact that the following properties, which are crucial for a comfortable room climate, are always fulfilled: BINDER-FREE, HEALTHY CLIMATE Since bricks are made from the natural raw materials loam and clay and fired at temperatures of over 1,000ºC, they are a guarantee for a healthy living climate. In contrast, bricks containing binding agents, such as sand-lime bricks, breeze blocks or concrete blocks, contain lime or cement. The binding agent ensures that the moisture remains in the brick for a longer period of time. Especially in the case of breeze blocks, the so-called core moisture is formed during construction when the building element is wetted, and its evaporation can last for several years due to the low capillarity of the blocks. This often leads to mould settling on the inner walls in the areas around the thermal bridges. FREE FROM TOXINS AND ALLERGENS Water, earth and fire: bricks are pure natural building materials. They do not contain fibres, do not develop dust or chemical substances. NO RISK OF MOULD GROWTH Bricks are always open to diffusion and contribute to optimum water vapour equalisation. The wall surfaces dry out very quickly due to the excellent capillarity, which is why the danger of mould formation can be excluded. ELECTRIC SMOG Invisible electrosmog is suspected of being harmful to human health. Double-shell, solid brick walls protect against radiation from mobile phone masts and power lines without the need for any additional measures. Due to their relatively wide wall thickness and high wall weight, most double-shell exterior walls can shield such radiation up to 100 percent.