EIFS | Family villa in Bayreuth

A façade clad in natural stone gives a building a very special visual appeal, as the example of a family villa in Bayreuth, which has been ready for occupancy since the end of 2021, impressively demonstrates. The architectural firm "RK Next Architekten" successfully realised the client's demanding requirements for an open design. A central element of the exterior wall was the maxit ETIC system with its system-optimised components. As with the polystyrene insulation boards, system-optimised maxit mortars were also used to create the natural stone cladding, enabling a durable, high-quality façade in terms of building physics.

The family home posed a planning challenge due to the elongated shape of the plot and its particular topography, as well as the client's very specific wishes. On the other hand, requirements such as the desired uninterrupted view of the Bayreuth Festival Theatre could only be realised thanks to the elevated hillside location.

A visual highlight of the three-storey flat-roofed building is undoubtedly the façade design in addition to the attractive staggering of the ground and upper floors. "The projections and recesses of the otherwise compact structure and the façade structure with the natural stone cladding made of travertine stone formats of different widths give the building a more compartmentalised appearance," explains architect Maximilian Küfner. "The appearance of the building is thus oriented towards the small-scale neighbouring buildings without sacrificing architectural individuality." Travertine natural stone is a particularly popular façade cladding in Italy's capital Rome, but has also long been used as a prestigious design feature in Germany. With its beige-coloured, dark speckled surface, the classic "Bauhaus Travertine" gives the buildings clad with it a high-quality character and is quarried in Germany by the company Traco (Bad Langensalza) in a dozen quarries.

Light-flooded living ambience

The client's central concern was to create a living concept that was as open as possible, allowing views in all directions. Floor-to-ceiling glazing, some of it two-storey high, creates a high degree of permeability in the living areas and ensures flowing connections between inside and outside. A special feature is the generous air space above the dining area, which welcomes family and guests with a high degree of transparency as soon as they enter the house. If you follow the cantilever staircase to the upper floor, which is visible behind a pane of smoked glass, you can look straight up to the sky through the glazed opening.

A striking feature of the interior design is the deliberate juxtaposition of extroverted, generously glazed living spaces with more introverted rooms. Typical of the latter are private retreat areas such as the bedrooms or the owner's wine cellar in the basement.

Monolithic façade with ETICS

The choice of monolithic masonry throughout with a thermal insulation composite system (ETICS) was not only due to the desire for an attractive natural stone cladding: The many projections and recesses of the façade in the terrace area required appropriately thick insulation anyway - due to the desired high level of thermal insulation. This allowed the use of a relatively slim and very heat-retaining load-bearing masonry made of sand-lime brick without thermal insulation problems.

Ultimately, in close consultation with the client and contractor, the decision was made to use 15 millimetre plaster on the inside, 24 centimetres of sand-lime brickwork, 18 centimetres of maxit ETICS with a dowelled reinforcement layer and 15 millimetre thick travertine cladding for the exterior walls on the ground floor. Instead of natural stone, a weather-resistant mineral plaster with two coats of paint was used as the final coating on the upper floor. This ensured the very low heat transfer coefficient (U-value) of the building envelope of 0.17 W/(m²K).

Natural stone façade in Bayreuth: The classic "Bauhaus travertine" gives the building a high-quality character with its beige-coloured, dark speckled surface.
Photo: Thomas Wolf, Gotha

Family home in Bayreuth: The driveway leading up to the garage and the natural stone cladding on the façade give the property a very prestigious appearance.
Photo: Edgar Schmeichel, Düren

External thermal insulation composite system and mortar from a single source

The unusual combination of an ETICS and the selected travertine cladding required the use of system-compatible components, as with all approved façade insulation systems. The maxit Group scored points here with its "Ceramic Joint Mortar": this is a frost and driving rain-proof, mineral dry mortar of compressive strength class M10, which also offers various colours according to maxit's joint mortar colour chart. The architect's positive experience with maxit was another plus point. As the painting company "Förster die Malermeister" (Gesees), which was commissioned to carry out the ETICS, generally favours the use of maxit ETICS, this manufacturer was chosen.

Specifically, the choice fell on a thermal insulation composite system that harmonises perfectly with ceramic cladding: the "maxit PS 035 speedy" insulation board (λR=0.035 W/mK) has an enlarged bonding surface thanks to its sawtooth-like milled surface, thus ensuring quick and safe processing. The total of around 350 square metres of insulation boards were bonded using the point-bead bonding method. The adhesive surface area on the substrate was around 60 per cent for absolutely secure fixing. Fabric reinforcement was then applied and the reinforcement layer was dowelled through the fabric when wet. A filler was then applied to level out any unevenness. This was followed by the use of maxit's "ceramic laying mortar". The hydraulically setting, highly tempered adhesive mortar is not only suitable for bonding ceramic coverings to ETICS: It can also be used on very slightly absorbent substrates, such as bituminous sealants or dense concretes. The travertine tiles in the Bayreuth villa were laid with the "Ceramic laying mortar" and then grouted with the "Ceramic joint mortar" as a slurry joint.

The end result was to the complete satisfaction of the clients and also testified to the high material quality of the individual components. "The close cooperation between all those involved in the construction, who all come from the region and already know each other from previous projects, also contributed to the high quality of the façade design," emphasises Küfner.

A showpiece in the outdoor area too

The building, which has been ready for occupancy since December 2021, proves that exclusive residential architecture is not perceived as a foreign body even in a housing estate characterised predominantly by classic detached houses with pitched roofs. An attractively designed attached garage and a pool, together with large terraces and greenery virtually all around the house, round off the living comfort in a convincing way. The natural travertine stone laid on the terraces and in the pool area ensures a particularly smooth transition from the building structure to the outside area.

In October, the special new building was honoured with the international "ICONIC AWARD 2023" for innovative architecture. One reason for this is the overall aesthetic appearance, to which the very well thought-out green planning also contributes. Given the proximity of some of the plants to the ground floor, another advantage of the natural stone shell will soon become apparent here: it is very easy to maintain at all times.