Wellhöfer 4D attic hatch and ladder which is pre sealed for airtightness and addresses a frequent weak point in Passivhaus projects with a cold roof construction. The product is a Certified Passivhaus Component. For product dimensions, see this PDF.
Manufactured and engineered in Germany and has been tested to stringent DIN standards to comply with airtightness and insulation requirements. The Wellhöfer hatch remains airtight even under blower door test conditions.
An airtight seal of the door itself is maintained by means of a pre-stressed spring which ensures the door remains airtight, even when a blower doortest is carried out.
The gap between the door and the hatch is sealed with a rubber gasket.
This durable seal has been tested against ageing.
An Airtight sealing system ensures that no air leakage occurs between the gap between ceiling and frame. This is due to the double sided adhesive tape and Insulation strip.