Wellhofer Airtight Attic Hatch

The Wellhöfer 4D attic hatch not only features a certified airtight and pre insulated attic door, but also features an independent airtightness sealing system which seals the hatch frame to the surrounding Timber joists, noggins or the adjacent airtightness and vapour control layer. The hatch door is not only 3rd party certified airtight door, but the additional hatch frame sealing system has also received 3rd party airtightness certification. The system has been used in many buildings achieving low energy and even Passivhaus levels of performance for airtightness.



The airtight seal of the hatch door is maintained by means of a pre-stressed spring which ensures the door remains airtight, even when a blower door test is carried out. This spring is full adjustable to the homeowner’s requirements. The airtightness of Wellhöfer 4D is 5 times better than that required by DIN 4108-2 and is certified to EN 1026:200-09.

The complete hatch also features a low U value of 0.78W/m2k certified to EN ISO 12567 – 1: 2001/02. It should be noted that this U value is for the complete system rather than a Single optimum position in the centre of the door.

When specifying a truly airtight attic hatch one should ensure not only that the door is airtight, but also, the means by which the attic hatch’s frame is sealed to the adjoining vapour control layer or timber noggin. One may install an attic hatch which has an airtight door, yet, the leakage area between the frame and the surrounding noggin can lead to an additional 70-100 litres of heating oil required per year! Therefore one cannot underestimate the importance of not only installing an airtight and adequately insulated attic hatch, but also to ensure the frame is also installed airtightly.