Insulating Plaster

The Oberbräu in Holzkirchen was built in 1896 as part of a brewery ensemble with stables and outbuildings.

After renovation and repair work, the listed building has been transformed into a cultural meeting point in recent years, which includes a theater, a cinema, a ballroom and a café.

The use was already determined at the start of planning. However, implementation of the construction project was difficult due to structural constraints and the requirements of the monument protection authorities. The necessary building insulation measures on the partially rounded building complex were to be carried out with dimensions and according to the historical model with rustic bosses on the first floor. In addition, raised window frames and decorative stucco elements should come into play again as facade decorations. The thick outer walls were not necessarily straight and vertical according to the existing, dimensionally correct dimension. It was simply not sensible to apply a thermal insulation composite system on the historic masonry. The planners and conservationists therefore decided on an insulation material that has almost been forgotten, the insulation plaster.

Not just for the outside

Insulating plasters have been manufactured as dry mortars for around 30 years. Organic or mineral light aggregates are used to create the thermal insulation properties of the plaster. Only the mechanical assembly of these insulating plasters by plastering machines and conveyor systems enabled the efficient processing of these products.

But insulating plasters are not only used for external insulation. For example, in buildings where external insulation is not possible or feasible, such as half-timbered houses with historic exposed half-timbering, insulating plasters are increasingly being used as moderate internal insulation thanks to new building physics calculation programs such as COND and WUFI. Due to their capillary properties, the diffusion behavior and their processing, insulating plasters, in terms of building physics, correspond to classic mineral plasters. The advantages of insulating plaster are particularly evident on geometrically difficult surfaces and very different substrates. Facades with bay windows, cornices and curves can be provided with a seamless and void-free insulation layer.

Variable and freely modelable

Irregularities in masonry can be compensated for by insulating plaster with their variable layer thicknesses and their cavity-free application. No compensation measures on the masonry are necessary in advance. Only in the plinth area, where insulation plaster must not be used due to its low compressive strength, do plinth and perimeter insulation boards have to be used. In addition to the variable layer thicknesses, mechanically applied insulation plaster has another advantage: insulation plaster can also be modeled. The planned rustic bosses and the facade trim elements made of the insulating plaster material could be modeled out of an insulating plaster thicker in these facade areas using plow planing. The enormously complex preparatory work for the production of the rustic bosses by lathing and multiple plastering with intermediate downtimes was thus not required for this construction project. Of course, enormous manual skills are required at this point. By means of horizontal constriction around the large building complex, together with the building curvatures, which are difficult to get under control, it was ultimately possible to create a remarkable overall picture that will take future use into account.which will take future use into account.which will take future use into account.

Since insulation plaster alone does not offer permanent weather protection, the surfaces have been reworked with a full-surface filler. A mineral finishing coat and a painting system were carried out on it.

Dipl.-Ing. (FH) Anton Merath, Baumit Photos: Baumit Source: Malerblatt 11/2012