Interview with Mag. Astrid Huber
In the first part of the interview we mainly dealt with the further education aspect of the Charterhouse Mauerbach. What other topics are covered?
In addition to further training, at the Mauerbach Charterhouse we o focus on research. The knowledge acquired in international research projects is then passed on to experts in courses and seminars. The research projects deal primarily with historical building materials. There were some projects, including EU projects, on liming technology or roman cement.
As a national research project, I would for example like to mention our sand project, in which we created a sand register of the natural sands of Austria for architectural conservation. This is actually a co-operation with colleagues of the scientific laboratory of the conservation and restoration department of the BDA and the association for promotion of architectural conservation. There is also a publication on the project that describes a selection of 30 sands in more detail. Sand in particular determines the characteristics of mortar. The project is currently being completed. The sand collection in the Charterhouse Mauerbach, created as part of the research project, currently comprises around 140 sands from all over Austria and is of course accessible to experts.
All sands are scientifically processed and information such as the sieve line, composition, possible uses and sources of supply can be found in a database. This is also available online on the BDA’s website to all those involved in architectural conservation. In particular, practitioners for architectural surfaces and stone, stonemasons, bricklayers and master builders can now use this source when they are looking for a specific sand: e.g. a greenish sand with mica or a reddish, quartz-containing pit sand for special stone supplements. To date, there has been no listing of all natural sands in Austria, not even historically. As a result, it was often difficult for contractors to find the right additive for their mortar. Especially when we think of un-mounted natural plasters, the sand also plays a decisive role visually: in addition to the colour, the sands also influence the surface structure of the plasters. Historically, sand has always been mined in the surrounding area, and transportation was complex and costly. The sand and the architectural surfaces created with it always reflected the cultural landscape of a region.
Today, the building industry mainly works with industrial plaster systems. However, if historical surfaces are to be supplemented or reconstructed, these systems do not help. Finished plaster systems generally have to be machine-compatible, so the grain size is very fine and special structures cannot be achieved; not to mention the physical characteristics of the building, which of course must always be adapted to the existing building. The individual composition of mortar, binder and additive in construction site mixtures and the operation is crucial here.
Another example of research are the projects that we started with BHOe – I would like to mention the INCREAS project, which was recently selected for funding by the EU Commission. Like in the MODI-FY project, which was the reason for founding the European Heritage Academy, the subject of further training is also at stake here. The Charterhouse Mauerbach will play a crucial role, as it will be expanded into an international Centre of Excellence for architectural conservation and traditional crafts. We are already known in expert groups far beyond national borders. We served as a role model for our neighboring countries, such as the Czech Republic or Slovakia, for setting up comparable institutions. The INCREAS project now offers the historic chance to make the Charterhouse Mauerbach internationally known as a Center of Excellence.
What is also there beside the areas of further education and research?
We have not yet addressed the topic of service and advice. The Charterhouse Mauerbach is basically the only truly independent information center in Austria for all questions relating to the architectural conservation and refurbishment of traditional houses. We are the contact point for all professional groups working on such old buildings, the acting restorers and craftsmen, the architects and of course also for our own colleagues, if they face problems related to the protection of monuments that go beyond everyday work. We are also happy to help monument owners, owners of traditional houses, e.g. if one has a problem with damp walls, house sponge infestation, leaky windows or facade painting.
Currently I have an inquiry on the subject of refurbishment of fair-faced concrete surfaces and oil painting on wooden windows on my table – we are dealing with all those questions related to a historic building, from drainage and facade repair to roofing with ancient material.
Usually, if people turn to a specialised company for help, they will be offered the company’s own process or product – it is difficult to get independent expert advice on the subject in question. The recommended measures are often unnecessarily far-reaching – possibly taking a sledgehammer to crack a nut – instead of advancing in small steps that are usually more economical and less harmful to the substance. As an information center for architectural conservation in the Charterhouse Mauerbach, the BDA offers an uncomplicated, independent and also free-of-charge alternative.
At the moment we receive 5 to 10 inquiries per week and usually answer to them via phone or e-mail, sometimes local appointments can happen. Our broad network of specialists in all areas of traditional handicraft and architectural conservation also supports us in case of special inquiries. Most questions, however, concern general topics, such as the characteristics of modern coating systems compared to traditional paints. We are also well positioned here and are familiar with current products, especially the plastering and painting systems on the market. It often already helps to ask the right questions in order to support the owner or operater in making an object-specific decision.
Are these national or international requests?
These requests are primarily national, however we also receive inquiries from neighboring countries. Just recently I received an inquiry from Slovenia about glass bricks from the turn of the century. The Slovenian colleagues are aware of our collection of historical glasses and we were able to date the glass bricks just by looking at the provided photos and name the original manufacturer. Maybe we can also find the appropriate supplementary material.
A similar request came recently from the Czech Republic. Here, too, we were able to find a comparative example in our collection of historical floor slabs, assign the ornamental tile from the turn of the century and find re-used material for the refurbishment of the floor.
Which actually brings us to our next topic, also being part of research: the material collections for documenting the traditional building trades. With the foundation of our department as a center for historical handicraft techniques in 1984, traditional tools, historical building materials and architectural details were also collected and researched. The material collections in the Charterhouse Mauerbach today include an extensive window and door collection, a collection of wooden floors and parquet panels, floor tiles and ornamental tiles, the brick collection and the stone collection in the lapidarium. This even contains the spectacular collection of building and decorative stones from the Vienna World Exhibition in 1873 with over 500 cubes of different stones. At that time, all quarries in the k.&k.monarchy were asked to produce a stone cube with an edge length of 6 inches (about 15.8 cm) with differently processed surfaces for the world exhibition. This collection is an incredible pool of knowledge, a reference book for conservationists, stonemasons and stone restorers to assign natural stones and to find appropriate supplementary materials.
Where were these stone cubes found?
The collection was handed to the Geological Survey of Vienna after the Vienna World Exhibition and was stored there in the basement. In 1998 we finally took over the collection. Due to the long storage, most of the paper labels on the cubes, where the name of the respective rock was noted, were lost. As part of a research project, our geologist Dr. Karl Stingl reassign the stone cubes to the respective quarries. That was a real challenge, as around 70% of these quarries are no longer in operation today – an exciting project about which we have also published a small brochure.
The material collections in the Charterhouse document historical building trade and are an important source of knowledge for us: They provide information on traditional construction engineering and applied techniques, such as coatings on different surfaces, oil painting on wooden windows, tinning on fittings etc. The collections are always part of the further training in our in-house courses, in order to convey knowledge in a clear way. Practical work is also done with the course participants in the collection depots.
I see a number of small brochures here – what is this all about?
With these small selection brochures we try to provide our research topics and collections for a wider audience. To date, there are brochures on the topics of sands, parquet floors, windows and stone available – the next project will be devoted to the brick collection.
I would also like to mention our special exhibitions here: Our courses and seminars take place mainly in the winter months when the construction sites come to a hold. In the summer months we also devote ourselves to Public Relations work and convey our tasks to a wide audience in special exhibitions and on the days of the Open Charterhouse.
In particular, owners of historic buildings use the opportunity to get professional advice. One of the most popular issues at the moment is the durability of box windows and their coating with oil paint. What to do if the paintwork flakes off, where one can find a craftsman who can repair box-type window properly and paint it again with oil paint or what does it need to take care of care and maintenance myself? Box-type windows in particular have good insulation characteristics if they are repaired accordingly. Considering sustainability and life cycle costs, they are hard to beat.
These windows will continue to function for another hundred years if they are maintained accordingly. Oil painting has proven itself here for centuries and is currently experiencing a renaissance. Paint systems are tight, penetrating water cannot be released and the wood under the paint starts rotting. The oil paint, on the other hand, always remains open to vapor diffusion, does not become brittle and is also repairable and maintainable – that means one can simply paint over weathered surfaces without having to remove previous coats.
We have to find our way back to the tradition of care and maintenance – if we take up this knowledge again and integrate ourselves into this tradition, we will pass on our historical buildings with their typical windows, with their doors, the cleaning and painting to future generations, so that they also can enjoy it.
Do these box windows have good thermal results?Yes. The air cushion between the window levels creates good insulating characteristics and is both sound and heat protecting. Insulating glasses that are offered on the market today top the thermal results of the box-type windows, however are not sustainable. As soon as the gases in the spaces between these glasses have evaporated, the thermal results deteriorate. This is also expressed in the guarantee periods for the insulating glass panes of around 10 years. Unfortunately, this development is often not calculated in the decisions and only current thermal results are compared with each other – the life cycle of a building is not taken into account!
Insulating glass windows are also not repairable and must be completely replaced after their time has expired. In many historical buildings (which are not listed), box windows and parquet floors were – and still are torn out and replaced by „disposable products“ such as plastic windows, click parquet or even laminate. These floors then have a half-life of five to ten years, but cannot be refurbished. That was one of the reasons why we dedicated a special exhibition to the topic of historical wooden floors – in order to raise public awareness for these values.
In the long run – and in the protection of monuments we think at least in decades – the protection, repair and maintenance of the substance is always more sustainable, economical and ecological. „Our historical buildings are built energy“ to quote Burghauptmann Reinhold Sahl and consequently also energy efficient per se. Especially today, when environmental and climate protection are becoming more and more important for each of us, historical stocks such as box windows, parquet floors and meter-thick walls should be protected in order to use our resources as gently as possible. Every repaired traditional window and every refurbished historical wooden floor protects the environment and prevents mountains of garbage!