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Pre-compressed Butyl Tape – Waterproof Exterior RAL Sealing, Outer LayerExterior Sealing

nZEB Systems

Pre-compressed Butyl Tape – Waterproof Exterior RAL Sealing, Outer Layer

Exterior component of the RAL 3-layer system — repels water, vapour permeable, expands after installation. Sd < 0.1 m, elongation > 300%, UV resistant.

Technical specifications

MaterialBitumen/acrylic impregnated PUR foam
Available widths10 – 60 mm
Compressed thicknesses2 – 20 mm
State at installationPre-compressed (expands after)
UV resistanceYes — weatherproof
Elongation at break> 300%
Application temperature-5°C … +40°C
RAL systemOuter layer (permeable)
VariantButyl (ext.) / Acrylic (int.)

Certified performance

Water tightnessClass W2 – W3
Vapour permeability Sd< 0.1 m (permeable — lets vapour out)
Elongation at break> 300%
UV resistanceYes — does not age in sun
Durability> 25 years
Role in RAL systemOuter layer — repels water, vapour permeable

Key advantages

  • Repels rain water W2–W3 — complete exterior waterproofing at lateral wind and heavy rain without silicone or filler
  • Vapour permeable Sd < 0.1 m — allows moisture from joint to evaporate outward, eliminating condensation and mould
  • Pre-compressed — progressively expands after installation, perfectly filling irregularities between frame and wall without manual pressure
  • Elongation > 300% — resists seasonal thermal movements of frame and wall without cracking
  • No silicone gun — fast, clean, repeatable installation without drips or marks
  • Mandatory outer layer RAL component — required for any installation energy certification

Pre-compressed butyl tape is the external component of the 3-layer sealing system according to RAL Montajeleitfaden — the German reference standard for certified window installation. Made from polyurethane foam impregnated with bitumen or acrylic, the tape is delivered in a pre-compressed state and progressively expands after installation, perfectly filling all irregularities between frame and wall without manual pressure and without silicone. The essential property that makes it indispensable is the unique combination: waterproof (W2–W3) but vapour permeable (Sd < 0.1 m) — rain water cannot penetrate from outside, but water vapour from the joint can exit outward, eliminating condensation and mould in the wall structure. Elongation at break of over 300% guarantees sealing integrity over the entire window lifetime, including under significant seasonal thermal expansion conditions. Neofort BIZ uses pre-compressed butyl tape in all RAL-certified premium installation packages and recommends it as the first step in any high-performance window installation.

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Pre-compressed Butyl Tape – Waterproof Exterior RAL Sealing, Outer Layer

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