Winflex-I Airtight Window Tape

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Winflex-I is an Internal, Airtight Window Tape, that seals between the internal masonry reveals and windows/external doors.

Winflex-I as quick to apply and very reliable product, can be as well used at ground floor to walls junctions and has a high vapour resistance according to ENEV, DIN 4108-7. Furthermore – you may bond our Airtight Window Tape to porous and rough surfaces such as bricks, blocks, concrete and wood. You can also plaster it over, making it ideal for masonry construction. It has a 15mm adhesive strip to adhere to the window or door.

Due to its special construction, the tape is flexible in crosswise direction. This allows it to optimally absorb movements within the building and ensures a permanent airtightness seal. The bonding between the Winflex-I and internal reveal can be sealed permanently and reliably with FORTAX 6400 internal sealant.

Winflex-I interior sealing tapes offer the following advantages:

  • Its flexibility in crosswise direction they compensate for any building movements.
  • Provides a permanent vapour and airtight seal.
  • You can plaster it or paint over. 
  • Contain no solvents, either on the adhesive strip on the seal or in the sealants.
  • Offer significant savings due to time advantages.
  • Compatibility with acrylic glass and polycarbonates.
  • Provides high adhesion of the sealing strip on all types of window frame.



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Technical Details

Red (vapour Impermeable)  
High quality polymer foil, non-woven material lining on both sides  
Temperature resistance:     
–30C to +80C  
Shelf life:                               
A minimum of 12 months at +10C to +25C in original packaging  
Processing temperature:     
+5C to +35C  
70mm, 100mm, 150mm, 200mm, 250mm, 300mm, 350mm & 400mm.  
Roll length:                             
Max. tensile linear:               
>450N / 5cm DIN EN 12 311 – 2/A  
Strength lateral:                   
 >80N / 5cm  
Elongation at max linear:     
>20% DIN EN 12 311 – 2/A  
Tensile strength lateral:     
Fire behaviour:                     
 Class B2 DIN 4102 – 1  
Class E DIN EN ISO 11925 – 2  
Airtight DIN 4108 – 7  
Driving rain proof:                 
>200 cm water column DIN EN 20811  
Sd value:                               
 Approx. 55 m DIN EN ISO 12 572  
UV/weather resistance:       
3 months max



  • Remove any window protective foil, and wipe the frame with a solvent to remove any undesirable surface residues.
  • Measure the required length of tape.
  • Remove the adhesive liner and apply tape adhesive strip neatly to the window frame.
  • While ensuring sufficient stress relief of the tape, identify where the other side of the tape will finish on the reveal.
  • Apply a 6mm bead of sealant (Fortax 6400 or PHS Adhesive Sealant) to the reveal.
  • Additional thickness may be required if the block work is especially rough.
  • Where the tape is being plastered over, additional sealant should be applied to ensure no movement of the tape.
  • Gently press the tape against sealant and allow to cure.


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