UNIFIX formed bricks for ductwork are a UNIversal wonder. They are suitable for F90 ductwork, for the uptake of flue gas lines as well as fire-resistant mantles for solid flue.

The UNIFIX series offers a wide range of diameters and possibilities.

“FIX” is synonymous with installation speed and simplicity.



An overview of the UNIFIX building material

  • UNIFIX formed bricks for ductwork are made of autoclaved aerated concrete with an average density of 0.5 kg/dm³, and are therefore particularly light
  • Attachments and cut-outs can be easily made using commercially available tools
  • UNIFIX formed bricks for ductwork have square outer dimensions, and a circular bore hole
  • Easy bonding with thin bed mortar
  • UNIFIX formed bricks for ductwork are approved both for the construction of “pre-assembled chimneys” as well as for the erection of duct work for flue gas pipes (general construction approval as ductwork and general construction approval as chimney work)
  • Fire resistance of UNIFIX formed bricks for ductwork: 90 mins.


UNIFIX is available in five standard sizes


  • Exterior dimensions 240 x 240 mm, height 500 mm
  • Open inner diameter 165 mm
  • For the uptake of exhaust gas lines for positive and negative pressure operation as well as for single-wall and concentric exhaust gas lines


  • Exterior dimensions 300 x 300 mm, height 500 mm
  • Open inner diameter 210 mm
  • For the uptake of larger-dimensioned exhaust gas lines as well as for the direction of suitable exhaust gas systems for pellet furnaces

UNIFIX 240 + UNIFIX 280 + UNIFIX 325 (new) 

  • Outer dimensions 360 x 360 mm, 400 x 400 mm and 450 x 450 mm, all height 250 mm
  • Open inner diameters 240 mm, 280 mm and 325mm, 
  • For use in larger exhaust gas systems
  • Despite their small size, these formed bricks still provide sufficient interior space for the uptake of chimney feed pipes for operation with solid fuel pipes
  • Optimal application for domestic chimney construction, particularly where the fuel and combustion technology are not yet clearly defined




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