Building Material Made of Cattail (Typha)

The agricultural production of cattail (Latin: typha) as a raw material for industrial application combines numerous ecological and economic advantages.

Cultivation and environmental effects

© Photo typha technik Naturbaustoffe

Typha (cattail), a plant that grows quickly and easily in all kinds of marshes throughout the world.

© Photo typhatechnik

The leaves have a fiber-reinforced supporting tissue filled with soft open-cell spongy tissue providing for amazing statics and an excellent insulating effect.

Due to an enormous productivity cattail is predestined as raw material for industrial application. Typha crops are robust natu­ral monocultures producing 15 to 20 tons of dry mass per hectare each year (approx. 150 to 250 m³ building material). This is the equivalent to the four- to fivefold value of what local conifer forests supply. The cultivation on fen ground and valley bottoms in Germany (as nutrient traps, CO2 sinks and erosion barriers, for water retention and biotope formation) would provide an appropriate basis to cover the total demand of insulation and wall buil­ding materials. The project "Cattail Culti­vation in Fens" funded by the German Environmental Foundation (DBU) under the direction of the Department of Agricul­tural Ecology of TU München (1998-2001) showed the practicability of cultivating typha.

Product development

© Photo typha technik

The Typhaboard provides structural and insulation properties in a single layer construction.

Due to the special structural properties building materials can be produced offering a combination of insulation and strength, which is unique on the market. The leaf mass of typha is especially applicable to produce innovative building materials due the structure of the plant. The leaves have a fiber-reinforced supporting tissue filled with soft open-cell spongy tissue providing for amazing statics and an excellent insulating effect.

In the past few years, the Fraunhofer Institute for Building Physics IBP investigated various product developments in laboratory as well as outdoor test facilities of in cooperation with the researcher Dipl.-Ing. Werner Theuerkorn. In the course of the research a variety of interesting products were developed of which a mineral-bound isotropic material for board production is of significant importance.

 

 

Product characteristics

© Photo Fraunhofer IBP

At Expo Milano 2015 visitors were able to explore the potential of this innovative building material for themselves.

© Photo Fraunhofer IBP

The Typhahouse was presented within the frame of the Expo Milano 2015.

The newly developed magnesite-bound typha board has an extremely high strength and dynamic stability despite a low thermal conductivity of 0.055 W/mK so that it is applicable to solve static problems. Moreover, this innovative building material possesses a lot of other positive properties:

  • renewable building materials with a very high resistance to mould growth
  • good protection against fire, noise control and thermal
  • insulation in summer
  • simple processability with all
  • common tools
  • relatively diffusion open and capillary active
  • low energy consumption in production
  • recyclability

The magnesite-bound typha board is a very competitive innovative building material, especially through cost-efficient production methods allowing a remarkable price reduction of essential building components.

Example of the application in a timber-framed building

© Photo typha technik

Typha grout is used to make the components draftproof.

© Photo Fritsch Knodt Klug + Partner

A sustainable renovation focused on exemplary ecological and energy-oriented improvements while maintaining the culture associated with traditional construction.

In case of the timber-framed building in Pfeifergasse 9 in Nürnberg with asymmetric building construction with a gabled roof with one roof side reaching down to the first floor and inadequate reinforcement of the supporting structure, the constructional problem was to restore the visibility of the timber frame construction, to observe the German Energy Conservation Regulations (EnEV) of 2009, and to consider the aspects of the preservation of historic buildings and the simultaneous stabilization of the building. The applied typha board material fulfills all these requirements. The exemplary material application was funded by the German Environmental Foundation (DBU) and the Bavarian State Office for the Preservation of Historical Monuments (Bayerisches Landesamt für Denkmalpflege).

With the typha board an extremely slender exterior wall construction of a thickness of 16 cm plus 4 cm plaster with wall heating is realized. Due to the simple processability and inherent stiffness the material could be adjusted to the irregular inclined walls. To achieve resistance to wind typha joint swelling mortar was applied to the joints and cracks in the wood by means of a cartouche press. The external plaster was directly applied to the board material as especially diffusion-open three-layer plaster of calcareous tuff sand and chalk and reinforced by the umbrella-shaped seed of the cattail.

The Fraunhofer IBP investigated the suitability of the wall structure over a measuring period of 1.5 years and determined a thermal transmittance (U-value) for the infill of 0.26 W/m²K. The U-value of the whole building (infill and timber construction) is 0.31 W/m²K. The low level of moisture applied by the swelling mortar and plaster dried out fast to a constant moisture contents in the wooden supports of below 20 M.-%. 

 

 

 

Research in focus

The cattail – an insulating material with real promise