Hydra Classic Wall Underlay
HYDRA Classic Wall underlay is a premium flexible synthetic underlay designed to be used behind exterior cladding systems.
It acts as a secondary weather-resistant barrier, protecting the building envelope from water ingress while allowing the safe passage of water vapour, contributing to a dry and durable wall assembly.
- Can be used with absorbent and non-absorbent claddings.
- Can be used with direct fix cladding and cavity applications.
- With masonry veneer in accordance with NZBC Acceptable Solutions E2/AS1 and E2/AS4.
- Can be used in all wind zones up to and including extra high when used with Rigid Air Barrier systems.
- Can be used as an air barrier in unlined spaces, such as attic spaces.
Product Code Roll sizes Coverage
- HYCL1370 1370mm x 37m 50m2
- HYCL2740 2740mm x 37m 100m2
- Can be used with absorbent and non-absorbent claddings.
Frequently Asked Questions
What is Hydra Classic Wall Underlay used for?
It's a flexible synthetic underlay installed behind exterior cladding systems as a secondary weather-resistant barrier, protecting the building envelope from external water ingress while allowing internal water vapour to pass through.
What claddings can Hydra Classic be used with?
Both absorbent and non-absorbent claddings, in either direct fix or cavity applications.
Can Hydra Classic be used behind masonry veneer?
Yes, in accordance with NZBC Acceptable Solutions E2/AS1 and E2/AS4.
What wind zones is Hydra Classic rated for?
Very high and extra high when used with a rigid air barrier.
Can Hydra Classic be used in unlined spaces?
Yes, it can act as an air barrier in unlined spaces such as attics.
What sizes does Hydra Classic come in?
HYCL1370 (1370mm x 37m, covering 50m²) and HYCL2740 (2740mm x 37m, covering 100m²).
How does Hydra Classic compare to Tekton Building Wrap?
Both are secondary weather-resistant barriers installed behind the cladding. Both are suitable behind brick veneer, and both are suitable in extra high wind zones over a rigid air barrier.
The difference is cladding compatibility. Hydra Classic is an absorbent underlay and can be used behind absorbent and non-absorbent claddings, in direct fix and cavity applications. Tekton is a non-absorbent underlay, so non-absorbent claddings must be installed over a drained cavity.