Moisture-variable vapor barriers
How the principle works
Why moisture-variable? The winter/summer principle
Classic vapour barriers have a fixed sd value – they slow vapour equally regardless of whether it is summer or winter. Moisture-variable vapour barriers are smarter: they automatically adjust their sd value to the ambient humidity.
Winter – high sd value
In dry, cold winter air the sd value rises to up to 20 m. The membrane strongly inhibits vapour and prevents moisture from penetrating the insulation.
Summer – low sd value
In warm, humid summer air the sd value drops to as low as 0.2 m. Moisture that has entered the construction can dry back out – active moisture protection.
Result – more safety
The construction can regenerate itself. Particularly important for renovation and blow-in insulation – where some moisture ingress can never be entirely ruled out.
Product overview
Targo VariVap or pro clima INTELLO – which membrane is right?
Our range includes moisture-variable membranes from two leading system manufacturers. Both offer variable sd values and high drying reserve – the difference lies in the construction and system compatibility.
| Product | Variable sd value | Key feature | Price from |
|---|---|---|---|
| Targo VariVap N | 0.2–20 m | High-performance vapour barrier for roof & wall | EUR 2.39/m² (roll 75 m²) |
| Targo VariVap S | 0.2–20 m | Reinforced – ideal for blow-in insulation materials | EUR 2.65/m² (roll 75 m²) |
| pro clima INTELLO | Hydrosafe® | For fibrous batt and board insulation materials | EUR 3.24/m² (30 m²) |
| pro clima INTELLO PLUS ★ | Hydrosafe® | Reinforced – for all fibrous insulation incl. blow-in | EUR 3.42/m² (150 m²) |
★ Bestseller – most frequently purchased in this category.
Straight to the product
The most important products at a glance
Targo VariVap N
Moisture-variable high-performance vapour barrier (sd 0.2–20 m) for roof and wall. Available as cut piece or roll 75 m².
Targo VariVap S
Reinforced moisture-variable vapour barrier – ideal for blow-in insulation materials. Available as cut piece or roll 75 m².
pro clima INTELLO PLUS ★
Reinforced Hydrosafe® high-performance vapour barrier – for all fibrous insulation materials including blow-in insulation. Bestseller.
Practical experience from blow-in insulation
Moisture-variable vapour barrier – a recommendation from practice
As a specialist contractor for blow-in insulation, we use moisture-variable vapour barriers every day – especially in renovation projects and blow-in insulation in existing constructions. We know the system requirements and recommend the right product for your construction, including the matching tape and connection details.
Frequently asked questions
Frequently asked questions about moisture-variable vapour barriers
What exactly does moisture-variable mean?
Moisture-variable vapour barriers change their sd value depending on the relative humidity. In winter (dry air) the sd value rises to up to 20 m – the membrane strongly inhibits vapour. In summer (humid air) it drops to as low as 0.2 m – moisture can dry back out of the construction.
What is the difference between INTELLO and INTELLO PLUS?
INTELLO is the standard version for fibrous batt and board insulation materials. INTELLO PLUS is reinforced and explicitly suitable for blow-in insulation materials. INTELLO PLUS is more robust and better suited to constructions with higher mechanical demands.
What is the difference between Targo VariVap N and VariVap S?
VariVap N is the standard version. VariVap S is reinforced and specifically designed for use with blow-in insulation materials. If you are planning blow-in insulation, we recommend VariVap S or INTELLO PLUS.
When is a moisture-variable vapour barrier absolutely necessary?
For blow-in insulation in existing constructions, for renovation projects with unknown moisture content and for vapour-open timber construction, a moisture-variable vapour barrier is strongly recommended. For standard new-build constructions, a classic vapour barrier may be sufficient.
Which tapes are compatible with moisture-variable vapour barriers?
System-compatible tapes must be used: Targo membranes with Targo adhesive technology, pro clima membranes with pro clima tapes – only then is the system guarantee maintained. We stock all matching products.
Can moisture-variable vapour barriers be installed by DIYers?
In principle yes – installation follows the same principles as for classic vapour barriers. What matters is the careful bonding of all connections, overlaps and penetrations. For unclear constructions, we recommend consulting us before purchasing.
Maximum safety for your construction
Choose the right moisture-variable vapour barrier now.
Targo VariVap or pro clima INTELLO PLUS – both with variable sd value 0.2 to 20 m.