A clay tile roof is more than just a roof

Roof tiled with Koramic Aleonard Pontigny, 1/3 rustic and 2/3 brown burnished
Would you like to renovate your roof, replace the roof cladding and improve the thermal performance or you are looking for a suitable roof construction for you newly constructed house? The following information helps you to make the right choice and provides a compact overview of subjects concerning the roof.

Functions of roof, roof construction and system solutions

You plan a new roof maximum twice in a lifetime: for a new building project or a corresponding adaptation in the course of the use. So it is worthwhile to get a good overview to be able to choose a suitable construction method and the appropriate roof tile models.

The roof is the main protective shell of a house and decisively affects its appearance. During the planning phase some important factors, such as location or construction style of the building, need to be taken into account. The combination of pitched roofs and clay tiles, for example, is a symbol of the European culture. The large variety of shapes, formats and colours of clay roofing products reflects traditional craftsmanship and helps preserve the regional architectural heritage across Europe.

The roof protects a building and the people living inside against external influences such as cold, heat, storm, hail, rain, snow, and noise. Consequently, the roof is exposed to extreme stress and loads in the course of its use and it is a complex system of different components. In order to ensure optimal functioning, insulation, roof system components and roof tiles should be coordinated with one another. Wienerberger and TONDACH® provide comprehensive roof system solutions from a single source to facilitate your decision.

Roof constructions and their structure

A pitched roof can be implemented with different construction methods. The pitch of the roof surface has an influence on the chosen roof construction and roof cladding. The roof truss, the load-bearing structure respectively the “skeleton” underneath the roof membrane, forms the basis for the subsequent load application and load transfer of the entire roof. The pitched roof has a very solid wooden framework as sub-roof structure (rafters and purlins), which not only supports the roof cladding but also itself. This structure is responsible for the roof shape, height and possible subsequent conversion underneath the roof and is mostly manufactured and constructed by experts (carpenters).

The roof insulation is part of the thermal insulation of buildings and makes a considerable contribution to reducing energy consumption. The insulation of the roof shall reduce the heat transmission coefficient (U value) of the roof and thus energy consumption. Both the homeowner and nature benefit from this reduction because less energy consumed for the operation of a building (heating, cooling) means, among other things, reduced CO2 emissions.

Regardless of the roof construction a building owner opts for, he should be aware of structural measures and observe regional weather conditions. Wienerberger Online Calculators, available at the websites of the single branches, additionally help – with regards to local conditions – to select protective measures against wind suction (wind load) or choose a suitable snow protection system.
 
A well-designed pitched roof will last a lifetime and longer. This very long lifespan translates into economic savings for its owner, who will not be obliged to regularly pay for roof maintenance over the years.

Wienerberger pitched roof solutions –“Everything from one source”

Roof solutions by Wienerberger include clay roof tiles, ceramic fittings and also technical components like underlays, storm fixation systems, snow retention systems, insulation, etc.

Besides the two main brands Koramic in Western Europe and TONDACH® in Eastern Europe, we provide Sandtoft and Keymer roof tiles in the UK, ZZWancor clay roof tiles in Switzerland and high-end plain tiles from Aléonard in France. Keymer and Aléonard both stand for long history and tradition, Keymer are genuine handmade British clay roof tiles.

Under the quality brand of Koramic, Wienerberger provides individually tailored solutions for all common requirements, that is
  • insulation systems installed on top of the rafters
  • diffusion-open underlays
  • a great variety of durable TONDACH® roof tile models
  • ridge / hip solutions
  • ceramic and non-ceramic accessories
  • as well as a wide range of different services
 
The roof solutions are combined as individual “packages”, which allow roof constructions according to European building regulations in the refurbishment and new construction segment through to the implementation of a passive house standard.
 

Innovation
 
Fastening system
New patented Sturmfix 2.0: The innovative fastening system for roof tiles has been enhanced and therefore not only provides maximum storm safety on the roof but also can be removed easily if needed, for example in case of repairs or subsequent installation of a roof window.
 
Koramic AluGrip-Rol – Roof Grip Extreme Technology
A fully-aluminium ventilated ridge and hip roll with the patented Roof Grip Extreme technology by Wienerberger for use on ceramic surfaces. Three times higher bond strength on glazed, engobed and natural red surfaces compared to the commercial standard Butyl.
 

Flat tiles
The development of roof tile models with flat visible surfaces and a straight, clear shape opens up new architectural design emphases and gives the buildings a new appearance. The use of these tiles on the façade also results in new interesting possibilities, with the application of tiles on both the façade and the roof being called “mono-cover”. See the example Actua at the end of the text.
 

Slate look
The combination of the natural appearance of slate with the excellent properties of clay in one product provides new possibilities in terms of look, shape and processing. Innovative approaches in the design and production offer a great variety of different surfaces and appearances. See the example Rivius (UK) righte below the text.

Pitched roof vs. flat roof

The roof as the upper termination of a building is executed in different ways depending on the angle of the roof pitch. When does one speak of a pitched roof?
 
  • Pitched roof: inclination angle of 15° to 70°
  • Low-pitched roof: 8° to 15°
  • Flat roof: < 8°
 
According to a study by TU Wien a house with a pitched roof is 12.5% more compact than a house with a flat-roof providing same living space. This makes the building more effective thermally, as it reduces the surface of the walls in contact with the outside world. Pitched roofs are especially common in areas with wet and changing weather conditions, whereas flat roofs are more popular in dry, hot areas.
 
 
Wienerberger has designed special regional products for low-pitched roof solutions. For a roof pitch between 10°and 15°, Wienerberger offers technically advanced roof tiles, fittings and accessories. These system solutions provide absolute resistance against severe weather conditions.
 
Pitched roofs have a firmly secured place in modern architecture. Their versatility makes them ideally suited for the implementation of innovative design solutions, resulting in the desired futuristic-looking rooftops that reflect the modern world.

Pitched roof has advantages over flat roof
 
A study by TU Wien (Vienna University of Technology)
The construction of a single-family house with a pitched roof (SDUA) instead of a flat roof (FD) results in CO2 savings of 26.21 tons over a lifecycle of 50 years.

Advantages of a pitched roof at a glance:
  • lower lifecycle costs over 50 years (up to 16%)
  • reduced CO2 emissions (up to 16%)
  • creation of additional space
  • freedom from maintenance
  • durability resp. reusability of elements
 
Why has a pitched roof so many advantages?
 
Environmental influences
  • Wind & storm
    At a pitched roof, wind forces break at the ridge. The suction power on the downwind side is only little. Small-format roofing materials are easily lifted by wind and drop back into their original position. At a flat roof, on the contrary, the wind current applies behind the ridge and generates a negative pressure, which lifts roofs like the wing section of an aeroplane.
     
  • Increasing frequencies of extreme weather events, as a consequence of climate change, challenge building structures. The structural stability of pitched roofs, however, allows the roof to withstand heavy loads resulting from snow or hail. Steep pitched roofs don’t have to be freed from snow manually. Clay roof tiles achieve hail resistance class HW4 (Ø 40mm).
    Reference: Hagelprüfungen IBS Linz, 2014 (AT), http://www.hagelregister.at
     
  • Pitched roofs guarantee fast water drain, water runs “away” from and out of the building without any water barriers. So there is no risk of water damages. Easy and simple collection of usable rain water is possible.
    Reference: Lebenszyklus unterschiedlicher Dachkonstruktionen, Forschungsbereich für Industriebau und interdisziplinäre Bauplanung, TU Wien, 2014 (AT)
     
  • Sound protection
    Noise has a fundamental impact on the comfort in buildings; even more so in urban areas, where traffic can be dense. A well-designed and executed pitched roof provides excellent acoustic insulation thanks to its combination of sound-absorbing materials. A pitched roof allows the owners to sleep soundly even in heavy rainfall. 
    Reference: Lebenszyklus unterschiedlicher Dachkonstruktionen, Forschungsbereich für Industriebau und interdisziplinäre Bauplanung, TU Wien, 2014 (AT)
     
  • A pitched roof significantly improves the thermal efficiency of a building thanks to the natural ventilation underneath the top roof layer. This ensures optimal indoor comfort both in winter and summer.
 
Economic benefits
  • Costs
    The costs for the building component “roof” (roof cladding and sub-structure) are lower for a pitched roof regarding both the purchase price and over the lifecycle (50 years). Running expenses are also relatively constant. Only after a period of 30 years, the need of renovation arises.
     
  • Repairs
    The roof cladding materials can be replaced easily and without complications.
     
  • With pitched roofs, the subsequent creation of living space beneath the roof can be done without the need of elaborate and expensive annexes or attachments. By fitting skylights into a pitched roof, it will also be possible to let sunlight in and create a warm and light-filled living space under the roof.
    Reference: Lebenszyklus unterschiedlicher Dachkonstruktionen, Forschungsbereich für Industriebau und interdisziplinäre Bauplanung, TU Wien, 2014 (AT)
 
Sustainability
  • Power generation on the roof
    Photovoltaic & solar installations can be integrated into the roof surface area and adopt the function of the roof cladding.
    Reference: Lebenszyklus unterschiedlicher Dachkonstruktionen, Forschungsbereich für Industriebau und interdisziplinäre Bauplanung, TU Wien, 2014 (AT).
     
  • Environment
    As compared to a building with a flat roof, a house with a pitched roof saves approx. 26 tons of CO2 over a 50-year lifecycle. This equals 200,000 km travelled by car.

Roof tiles – general overview, production, raw material / colouration, recycling, accessories

Constructing in an economical manner is an important condition for architects and building owners, but it is often ignored that those building materials are economical which lasts longer – and not always the ones, which costs less. Costs for repairs and maintenance may quickly exceed the amount saved when buying the component. Those calculating costs over the long term, will decide for quality and lasting operative readiness. This is particularly true for the tiled roof as compared to other cladding materials such as concrete roofing tiles, slate or metal.
 
Clay roof tiles
Modern roof materials such as clay roof tiles are used for single-family homes and apartment buildings, office and industrial complexes as well as refurbishment projects. The production process is based on the four elements of earth, water, air, and fire. The natural components promote a healthy living climate, provide reliable protection for residents and are additionally recyclable.
 
The blanks are produced from a clay mixture, shaped as desired in a moulding process, dried and subsequently fired – that’s how a pure and natural ceramic product is manufactured. At Wienerberger, a computer-controlled production process and continuous quality control ensure that only top quality products are supplied.
 
The colour of clay roof tiles is determined by the natural composition of clay. For natural red tiles, ferrous oxide contained in clay is responsible for the slightly iridescent colouration. If oxygen is deprived during the firing process, the unglazed ceramic material turns bluish.
 
Another, almost unlimited colour spectrum is achieved when applying and firing clay slurries and their mineral composition. They are firmly burned in the roof tile and do not fade.

Each one of the different shapes with its typical, characteristic features has developed from regional conditions. The following main groups can be classified for roof tiles:
 
Tiles with interlocking
  • Flat tiles
  • Profiled tiles (Pan tiles, Tempest tiles, Reform tiles, Mulden tiles)
Tiles without intelocking
  • Plain tiles
  • Overlapping tiles (Hollow tiles)
  • Over and under tiles (Monk&Nun tiles)
Besides roof tiles for the roof area there are special ceramic accessories for the cladding of ridge, eaves, verges and hip. Special ceramic accessory tiles such as ventilation tiles, antenna passage tiles, vent pipe systems etc. additionally ensure the functionality und permanence of the entire roof.
 
Wienerberger clay roof tiles are available in a wide variety of colours and shapes. Our portfolio offers architects and end customers complete energy-efficient solutions for new construction and renovation projects.
 
Why is a tiled roof the most economic, safest and most beautiful choice for the roof?
  • Low maintenance
    Clay roof tiles are solid and thus especially robust and dimensionally stable. They are insensitive to environmental influences such as heat, cold and frost. As a result, roofs covered with clay roof tiles require very little maintenance and guarantee a constant quality and beauty.
  • Durable
    Clay roof tiles have a service life of 150 years. à Reference: Untersuchung der Lebensdauer von Baumaterialien für Fassade und Dach, Extra Muros, Belgium 2009 (BE)
  • Flexible
    Tiled roofs are especially flexible. In case of annexes and refurbishments, clay roof tiles can be quickly, easily and cost-efficiently installed or replaced.
  • Sustainable
    If a building has to be demolished, clay roof tiles can be sorted by type. This allows their quick and easy recycling or reuse for new roofing, rooftop greening, road pavements and the improvement of the water absorption capacity of soil substrata. 
Cultural heritage
Pitched roofs with clay roof tiles are an expression of architectural identity and part of the European building tradition. Since the 14th century clay roof tiles have been widely used throughout Europe. Several cities like Prague, Dubrovnik, Graz, Lisbon, Nurnberg or Florence are especially beautiful and famous because of their red roofs.
 
Ecological footprint and product optimisation
Wienerberger continuously works on the optimization of roof tiles by using Finite Element Method (FEM) with the aim to:
  • reduce material consumption while keeping or even increasing the mechanical resistance and durability of the tile
  • reduce primary energy consumption in the production process
  • optimise performance of tiles on the roof
  • add new features like variable gauge, storm fixation, …
 
Re-use and recyclability
Clay tiles are a natural product known for its durability. There are numerous examples of clay-tiled pitched roofs that have lasted over a hundred years. This keeps the environmental impact of the roof to a minimum over a long period of time.
If a building using natural resources has to be demolished or is no longer needed, it still forms part of the sustainability cycle. Clay tiles and masonry products can be reused or recycled in the production process for further use or for other purposes.
 

Roof renovation

The roof of a house is exposed to a variety of different weather conditions – rain, wind, snow, hail, etc. When it comes to renovating a roof Wienerberger offers high quality, perfectly matched roofing components that provide lasting protection and preserve the building’s integrity for many years.

A renovation in the roof area is principally equivalent with a new construction since not only the roof tiles are replaced but frequently the complete roof structure has to be adapted and a refurbishment and thermal improvement is carried out. If only the roof tiles are replaced, preferably tile models with a large sliding clearance are selected, because such types can be installed on the existing battening, which does not have to be renewed.

Clay roof tiles are applied for single-family homes and apartment houses, office and industrial buildings as well as for refurbishment projects. When maintenance is necessary, it is easy and requires only quick maintenance checks. Replacement of clay tiles is simple too.

Wienerberger provides a comprehensive product range that includes all variants from historic roof tiles to contemporary flat tiles in various sizes. With innovations such as the Stormfix fixing system, high-performance insulation and solar systems, Wienerberger has developed advanced solutions for sustainable buildings.

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