Facade Renovation

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-11-26 11:39

Using the example of a listed apartment building in Leipzig, the authors explain which aspects need to be taken into account when renovating facades.

Photo: Baumit / Müller

At the turn of the 19th and 20th centuries, a large number of new residential quarters and apartment buildings were built in Leipzig as a result of population growth. During this time, the building at Hahnemannstrasse 7 was also built in 1909. Stylistically, the object shows elements of the later Art Nouveau style, albeit not in their pure form, with decoratively curved lines as well as extensive floral ornaments and the inclusion of symmetries.

Rather, there are also hints of the reform style that started later but developed in parallel with Art Nouveau. Reduced forms and rusted surfaces can be seen here using traditional materials and features. Both styles combine the abandonment of the historical construction forms and the intensive search for new decorative design options, which can be found in the building.

Facade renovation factors

When restoring, renovating and reconstructing monuments and renovating historical objects that are particularly worth preserving, the current state of the building and future usage requirements must be taken into account. The existing salt and moisture pollution as well as damage due to aging, environmental and usage influences must be observed. They require sufficient consideration and attention when redesigning. Therefore, before starting work on the property, the essential aspects and the objective of the renovation work must be clarified with all parties involved, including the questions:

• Which measures are necessary and permissible to control the damage caused by the building and for thermal improvement
• which external appearance the building should receive, which plaster structure (e.g. with different findings) the facade should receive
• whether the building materials used in the inventory should be modeled and reproduced using today's options
• whether the binders found in the course of accompanying studies can be used in the new product
• which changes or deviations are necessary and permissible

Modern or historical building materials

Everyone involved should be aware that the original composition of the old plaster stock changes over the course of decades as a result of weather and environmental influences. Basically, however, the mortar analysis, the time frame of execution and the condition of the old mortar taken for examination, taking into account its location on the object - including the influences during sampling - allow conclusions to be drawn about its original composition.

With the right objective in mind, technical and specialist knowledge and a large portion of common sense, it is possible to use both products from the standard range and separately recreated products - regardless of whether they are masonry, jointing or plastering mortar Combine and use object. In this way you can achieve the same visual appearance as the construction findings show. In addition to a corresponding material concept, the handicraft technology and the handicraft skills of the performers play a decisive role.

Remediation costs

Here, too, all those involved must be aware that the adjustment of the material means that both the plastering mortar that is reproduced and the execution of plastering mortar in traditional handicraft technology involve greater effort. The cost framework can only be determined and maintained together with the client, the specialist planner and the specialist company carrying out the work.

Last but not least, the technical aspect of the measures to be carried out must not be neglected. The client and the builder can expect that even a “historical renovation” will be largely permanent. When using replacement mortars, they may only deviate as far as is necessary to control the damage to the building.

In addition to the static and building physics considerations of the building to be renovated, the renovation of the masonry with the aspect of aesthetic design requires a closer look and analysis of the condition of the building.

The found plaster base tells of its often eventful history after the old plaster has been removed. If you take a closer look, you will see - from the time of construction to various changes and conversions - the times and the building materials and processes available in the area.

Building damage analysis

Damage to the masonry, for example due to moisture and building salts, biological contamination and cracks in the plaster and sometimes in the masonry, testify to the stress on the property. Whether a fundamental construction error caused damage here, only gnawed the ravages of time, or whether well-intentioned attempts at reworking with the wrong materials contributed to the current state that there was a need for renovation.

As part of the facade renovation of the Hahnemannstrasse property, the characteristics of Art Nouveau and Reform style described above were restored on the street facade. Overall, large areas of the existing and stable plaster on the facade could be preserved and only thinly coated with a suitable facade renovation mortar. Floral elements and structures were - depending on the degree of conservation - renewed or improved. The structural surfaces on the facade were created as lyre plaster with traditional handicraft techniques and with plastering mortars according to the previous examination and sampling. In the plinth area, the stone plaster surfaces so typical for Leipzig were reproduced. Stone plasters - like concrete - achieve very high strengths. The surfaces are usually scratched by stone masonry processing after hardening. The surcharges used - mostly white, gray and sometimes black - become visible in a uniform matrix. If stone plaster surfaces show a smooth surface, then they are not reworked like a stonemason, but - as is also practiced on the base of Hahnemannstraße 7 - washed in a fresh state and later etched off. It is also possible to sand the surface.but - as also practiced on the base of Hahnemannstraße 7 - washed fresh and later etched off. It is also possible to sand the surface.but - as also practiced on the base of Hahnemannstraße 7 - washed fresh and later etched off. It is also possible to sand the surface.

Old building renovation indoors

Inside, the walls were provided with an insulating plaster on the street side. Especially the use of internal insulation requires special attention to building physics with regard to the existing building structure, materials used, connections to ceilings and integrating components as well as later use. The courtyard facades of the buildings built around 1900 were all relatively simple and rarely showed decorative elements. For this reason, this facade side was given a classic ETICS based on the geometrically simple and reduced design.

Starting from a restoration goal, intensive investigations up to the reproduction of historical plaster structures and the application of traditional processing techniques, buildings worth protecting can be preserved and used in the interest of the owner.

Further information:

www.baumit.de

Products used

• Plastering mortar from the series of historical HR recipes
• Stucco Stuccoco Grobzug FG 88, Feinzug FF 89, Mono SM 87
• Facade reworking with multiContact MC 55 W
• ETICS EPS (courtyard side)

Forßbohm & Söhne Bauunternehmen GmbH in Markkleeberg received the 3rd prize for the work on the Hahnemannstrasse 7 apartment building in Leipzig. The 2018 monument preservation award. Outstanding monument preservation services are recognized by craft companies from the Leipzig Chamber District.