Wellhofer Airtightness Insulated Attic Hatches

Wellhöfer is one of the world’s leading producers of high performance attic  hatches and space saving stairs, manufactured in Wurzburg Germany for more than 60 years. Their range of products have been tested to stringent EN & DIN standards surpassing airtightness and insulation requirements.

Wellhöfer attic hatches feature a fully insulated and airtight attic door.  Wellhöferalso are the only attic hatch manufacturer to adopt an independent sealing system for the hatch perimeter to adjacent building elements (i.e. noggins and timber joists within ceilings).

The Wellhöfer products are suitable for new builds or retrofits and provide a cost-effective contribution to a low energy home rating.

The long-term durability of an attic hatch is critically important. In recognition of how cold and humid an attic void can become in winter,  Wellhöfer have certified and tested the 4D hatch under extreme climate conditions equivalent to that required for external doors on buildings; to EN 1121.

The importance of installing an airtight insulated attic hatch

  • The opening to an attic space is a weak point in any building. Due to its location between the warm living space and the cold attic space.
  • The installation of an un insulated attic hatch/ladder can reduce the overall U value for a ceiling by up to 20%.
  • Wellhöfer attic hatches have been tested to the same standards (Climate Stability class 3) as external windows and doors to ensure they are able to cope with the colder more humid climate conditions often experienced within attics.

Airtight ceiling connection

Wellhöfer airtight attic hatch

Up to 70% of an insulated attic hatch value can be lost due to inadequate sealing upon installation, this will result in energy loss, structural damage and risk of mould. The Hoka twin wall sealing system implemented in  Wellhöfer attic hatches ensures the prevention of these risks.

Improper sealing of the hatch perimeter to an airtight envelope can result in a hole the size of a A4 page resulting in significant additional heating costs, condensation risk within the attic and a reduction in comfort.

The Benefits

  •          Improved comfort in the home
  •          Reduction in overall heating costs
  •          Condensation risk reduction
  •          Reduction in the risk of thermal bridging

The  Wellhöfer attic hatch also surpasses the onerous health requirements set by the Sentinel Haus Institute in Germany by 9 times, ensuring the risk of off gassing of any harmful volatile organic compounds to installers or end users in minimised.

In addition to the heat loss results, the Psi – the generated temperature response illustrations below demonstrate by way of heat flux vector arrows the much-improved distribution of heat loss through the ceiling junction. When compared with the uninsulated hatch (on the right) where all the heat loss was largely focused directly through the uninsulated unit. The low temperature created in this area returned to a minimum surface temperature (critical temp point of 10.29°C. Much lower than the part L recommended 14°C to avoid surface condensation and subsequent mould growth under these conditions

Wellhöfer - distribution of heat loss through the ceiling junction

Thermal imaging results showing the heat loss between an insulated attic hatch & non-insulated attic hatch.

Non Insulated Attic Hatch v's Insulated Attic Hatch


Standard Stock Sizes 600mm x 600mm  
Sealing System  Hoka twin Wall Resistant against temperature / environmental influences and ageing. 
Cover Profiles Plastic White with pre-mounted adhesive tape.
Lifting Mechanism Lever / Spring System Balances weight of the stairs
U-Value   0.75 W/m2k
Air-tightness Class Class 4  Sealing Value, a = 0.02 m3/hm (daPa)
Lock Magnetic x 2 Two magnetic catches with 5kg retention force

Additional Extra's
Special order, lead times apply

  Custom sizes available on request


Fergal Written By: Fergal Flatley (technical support) Ecological Building Systems

Posted on Monday, 27 August 2018
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