Air and vapour barrier DELTA®-NOVAFLEXX

Innovative vapour barrier with humidity-variable SD value for roof renovations. For indoor as well as outdoor installation.

Airtight roof renovation with DELTA®-NOVAFLEXX: Inserted into the compartment from the outside and guided over the rafters. Installed from the inside under the rafters.

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    Verarbeitung von DELTA®-NOVAFLEXX
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    Verarbeitung von DELTA®-NOVAFLEXX
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    Verarbeitung von DELTA®-NOVAFLEXX außen
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    DELTA®-NOVAFLEXX - Verklebung im Überdeckungsbereich mit DELTA®-MULTI-BAND
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    Verlegung von DELTA®-NOVAFLEXX
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    DELTA®-NOVAFLEXX in der Außenanwendung
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    DELTA®-NOVAFLEXX in der Innenanwendung


  • Variable Sd value
    The Sd value of DELTA®-NOVAFLEXX changes depending on the surrounding humidity. The polyamide film reacts specifically to fluctuations. In extreme cases, the SD value over the entire are or at points can be reduced from 5 m to 0.2 m. If the humidity changes, the material density changes as well. DELTA®-NOVAFLEXX becomes more permeable and the vapor diffusion resistance decreases, when the air humidity increases.
  • Suitable for roof renovations both from inside and outside: In contrast to conventional air and vapor barriers, DELTA®-NOVAFLEXX can be laid over the rafters in loops. The moisture arising in the upper part of the rafter can diffuse out in connection with the diffusion-open DELTA® roof membranes.
    Inside: DELTA®-NOVAFLEXX - laid airtight and variable in humidity - offers, in connection with vapor-permeable DELTA® roof membranes, optimal protection of the roof structure and creates a high living comfort.


DELTA®-NOVAFLEXX can be installed quickly, safely and inexpensively, thanks to the robust and tear-resistant special fleece.

The new surface with halftone printing supports precise and fast processing. The processor is always facing the printed coating side.

At a roof conversion from the inside:
DELTA®-NOVAFLEXX can be applied parallel or across the rafters and is fixed linearly to the side of the rafters with pressure battens (for example trellis battens). Tackle clips or broad-headed pins can be used as assembly aids. When overlapping, the membrane is glued with DELTA®-MULTI-BAND. On smooth surfaces such as gable walls, purlins, chimneys, etc., DELTA®-NOVAFLEXX is connected airtight with DELTA®-TIXX / -TIXX VDR On rough surfaces, the connection is made with DELTA®-LIQUIXX or the DELTA®-KOM-BAND and pressure strips. Corners or cables can be sealed with DELTA®-FLEXX BAND FG 80 / 150 or DELTA®-FLEXX BAND F 100.

In case of a covering/roof renovation from the outside:
First, remove the roofing and the old insulation. In case of nails or screws protruding from the inner lining, insert a thin, covering insulation board. In all other cases, apply DELTA®-NOVAFLEXX directly on the inner lining: roll out parallel to the eaves or from ridge to eave over the rafters and try to apply tension-free into the rafter fields. Fix along the rafters with linear pressure (for example trellis battens). The membrane overlapping must be 10 cm.
In connection areas try to connect as airtight as possible with the DELTA® system accessories and battens.
Then cut the insulation to the width of the rafter field according to the manufacturer's instructions and insert it.

Technical data

Material Polyamide film with laminated special fleece.
Reaction to fire Fire class E, EN 13501-1
Tensile strength approx. 150/130 N/5 cm entsprechend DIN EN 12311
Sd-value approx. 5 m in a dry environment
approx. 0,2 m in a wet environment
Weight approx. 90 g/m²
Roll weight approx. 6,8 kg
Dimensions 50 m x 1,50 m




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Would you like information on detailed product properties, use cases or other technical topics?
Then feel free to contact our application department on +49 2330 63 578 or

Do you have questions about prices, availability or the status of your order?
Our sales service will help you with these matters on +49 2330 63 636 or