We are close to completing our building project (our first); a contemporary stone/oak clad timber frame, and have recently had the air tightness test carried out. We were hoping for a good result, somewhere under the 3.0 mark, but were amazed (as were the testing company) by the actual result of 0.296. Can anyone tell us how this ranks? What is the UK record for instance; and what will it mean from a practical point of view in terms of the energy efficiency of the house?

David & Jackie Oliver

  • Anonymous

    I think you’ll find that’s among the UK’s highest – there is quite a lot of competition if you get involved in the Passivhaus circle where the airtightness result is a source of considerable pride and competition. From my cursory monitoring, I think people have claimed 0.1, but can’t be sure. Either way, considering the minimum requirement under building regulations of 50, it’s really rather impressive! Hope you’ve got a MVHR system planned!

  • Mark Brinkley

    It’s such a low score that I would be a little suspicious of the result, esp if you weren’t looking to achieve a low score. Are you sure it’s the figure tested at 50 pascals (which is what the pressure testers work at), and not re-interpreted for what that might mean at normal air pressure?

  • David Oliver

    We were a bit suspicious about the result too; as were the consultants who did the test. The result was definitely at 50 pascals and was double/treble checked to ensure accuracy. We were certainly looking for a low score, but as first time self builders we weren’t sure what lengths we would need to go to get it. It was quite surprising to get such a low result as there was no rocket science in what we did; simply basic physics, common sense and attention to detail.

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