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Wellhofer Airtightness Insulated Attic Hatches

Fergal Flatley

By Fergal Flatley

Monday 27th August 2018

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.

Wellhofer Airtightness Insulated Attic Hatches 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 and are also 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 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. Overall, Wellhöfer products are suitable for new builds or retrofits and provide a cost-effective contribution to a low energy home rating.

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.

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.

Hoka twin wall sealing system used in Wellhöfer attic hatches.
Hoka twin wall sealing system used in Wellhöfer attic hatches.

The Benefits

Heat loss is greatly reduced due to the tight fitting insulation above the hatch door
Heat loss is greatly reduced due to the tight fitting insulation above the hatch door
  • 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 where all the heat loss is 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

Technical Details

Standard Stock Sizes: 600mm x 600mm     

Sealing System: Hoka twin wall; pesistant 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

Wellhofer's lever/spring system balances the weight of the stairs
Wellhofer's lever/spring system balances the weight of the stairs

Blog author

Fergal Flatley

Fergal Flatley

Technical Sales & Certified Passive House Tradesperson

Fergal  is a qualified construction project manager, he has a keen interest in green building and the development of biodegradable materials for construction and so went on to complete a B.Sc. in Advanced Wood & Sustainable Building Technology at Sligo I.T. Following this, Fergal completed an honours degree in Construction Project Management before joining Ecological. Most recently, Fergal has successfully completed the Passive House Contractor exam run by the Passive House Institute in Germany and is fully trained on low energy detailing.

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