Non-ventilated structure


Increasingly, the designer seeks for a slim roof package, making it different from the traditional structure with a relatively high ventilated cavity. Also with renovation of roofs, the thickness of the total package can be a problem. The choice is on a non-ventilated, vapour-tight system with the advantage of a slimmer design.

In a warm roof construction there is no ventilation between the insulation and roofing. To prevent condensation, the construction has to be damp proof. Water vapour that collects under the zinc surface due to internal condensation or nocturnal radiation will flow over the separation layer. This is a vapour permeable, structured separation layer. The construction should be a vapour-tight system with a µ.d (or sd) value of at least 150 meters.


In the application of vapour-proof systems risks are present that may affect the functionality and longevity:

  • mutual seams that are not properly taped
  • no rigid substructures
  • penetrations, which can cause leaks
  • leaks that may occur through careless installation and detail mistakes


Benefits of vapour-tight against the ventilated construction:

  • considerably more design freedom for architects and developers
  • a slim design and better fire safety, because no ventilation cavity is needed
  • easy to handle and therefore time saving during assembly
  • high-quality noise damping and insulation
  • the roof or façade construction is rapidly rain-proof, which accelerates the building speed

Responsibility – Warranty

The architect and/or contractor is responsible for the implementation of the vapour-proof system.
Consultation with the zinc worker is needed to limit or exclude the risks of this application.
The supplier of the various building materials simply provide warranty on the material provided by them. After processing these materials, the contractor is responsible for the warranty of the complete structure.

NedZink NOVA Pro-Tec

NedZink NOVA Pro-Tec is process-produced patinated Titanium zinc with a protective coating on the backside for application on either ventilated and non-ventilated constructions. This protective coating consists of a 2-layer polymer coating system which protects the zinc against the effects of water-vapour and other substances. The excellent processing properties of zinc are retained. NedZink NOVA Pro-Tec is mainly recommended forunventilated, damp-proof roof constructions and wall cladding.


Note: when condensation problems occur in the construction the zinc is not affected, but the moisture may have drastic consequences for the construction and the insulation values to be achieved.

The PUREN ® insulation element for metal roofing and cladding

(formerly known as the Endele system)

The PUREN insulation systems are ideally suited for use in unventilated constructions. After quick and easy installation the system is 100% damp-proof, which avoids condensation problems.

The PUREN Steep roof insulation component

This element consists of:

  • high performance PUR/PIR rigid foam insulation material
  • aluminium outer layer on both sides (50 µm) for full-surface insulation above rafters with no thermal bridging
  • topside with additional lamination made of polymer bitumen strips with angled self-adhesive overlapping side joints
  • edge-wide:  all-round tongue+groove joint; edge-narrow: tongue+groove joint at the front end stepped profile at the long side

The product range of PUREN insulation systems covers a wide range in combination with zinc roofing, cladding and other applications.


The vapour-tight FOAMGLAS® insulation system

Because in a warm roof system there is no ventilated cavity between the insulation and the roof, the air-tight FOAMGLAS® material can be applied. Internal condensation or condensation by nocturnal cooling is therefore no longer an issue. This is an important difference from a traditional rear ventilation construction.

This version with FOAMGLAS® is slimmer and can be used in virtually any shape. There are virtually no limitations on the shape, pitch or length of the roof. The system is ideal in combination with our product range and NedZink NOVA Pro-Tec, with the backside coating, in particular.

For the FOAMGLAS® roof and façade applications a special metal fixing plate is developed that is glued onto the insulation material. The insulation itself is again adhered tot the substrate. This leads to a construction where the roof with no ongoing attachment to the substrate can be Realized. And this means no cold bridges and no leaks.

The vapour-tight system can be applied to different kind of surfaces.


Example:  construction on a metal deck.

  1. Titanium zinc cladding
  2. fixing clips
  3. separating layer
  4. bituminous waterproof membrane
  5. metal fixing plate
  6. top coat of hot bitumen
  7. FOAMGLAS ® – insulation slabs
  8. slabs laid in hot bitumen
  9. metal deck