MartinI

For AGD I meant Above Ground Drainage ?

Thanks to all, I must admit that I hadn't expected so many responses so quickly, if I had, I would have been online sooner. To add a little detail, I am a Certified PH Designer, and I have been studying PH for more than a decade now. I'm not being all that hands-on, it would slow the build, though I do tend to be on site about 4 hours most days keeping an eye on things and doing what I can. To respond to Russdl: I made sure that our house is a pretty simple box shape, with a side lean-to construction (the latter basically a planning requirement) - no problematic dormers or chimneys. We are building at Long Four Acres. We'd love to find the reason for the loss in performance before proceeding, but we cannot really afford to delay the trades. The impression we got is just that a lot of what was okay previously, is a bit less okay now; thus it is a lot of small issues rather than any major one. Thorfun rightly asks what has changed since the MBC. 1) I put conduits through the wall for power and other services, these all had grommets; Some conduits have now been permanently sealed, others had a temporary seal for the test 2) MBC cut lots of holes in the ProPassiv board to blow in the cellulose, the discs were replaced and well taped in. 3) Two windows had to be replaced, these were taped in at least as well as the original windows; however a pane wass cracked during this exercise, and is yet to be replaced. 4) AGD is as yet incomplete, but again was carefully taped. These were all checked with a smoke pen during the test and other than small leaks nothing untoward was found. But I am now adding SL tape to seal the small leaks. I had rather assumed it was required to do an as-built final test for BC, but perhaps if one betters 0.6 early on then it is rather a given. It's disappointing not to find others who have done second tests. Personally, if we had time and funds, it would be best to stop work, reseal everything and retest - but this isn't really something I can do. Perhaps if our second test had been terrible... but actually it's around 0.8, so I'm reasonably confident I can get it back under 0.6 - it would just be good to be certain. Oh, and more leakage is a moisture in the walls issue as much as a need for extra heating. thanks all

We are self-building/managing an MBC Passivhaus near Norwich, just starting plaster-boarding. We are aiming for Passivhaus Certification. Our first MBC air-test was okay, 0.47ach, despite (and it seems others of you have a despite) there being a couple of areas where air-tightness could have been better. Having remedied these areas, and been diligent about sealing penetrations, I'd anticipated an improved result, however our recent second air-test wasn't to the required Passivhaus standard of 0.6ach. We checked what we could with a smoke pen, but couldn't find anything significant. Has anyone had similar circumstances, and did they manage to discover why? I'm applying additional taping to window reveal corners, in the hope that this is enough. thanks in anticipation.