Airtightness test booked - how to get the best from it?

[kla456]

Air tightness is hard to achieve, especially with a revovation project (passive haus accept a lower standard for refurbs). Mine is a 1950s bungalow with brick cavity walls. For air tightness we replastered one coat externally, before 200mm insulation and acrylic render and connected the extenal wall air tightness line (wall plaster) to the roof air tightness line (OSB onto rafters, edges bedded in silicone - re-roofed the house at the same time. The problem with the test is the cost/visit if you don't (you won't) achieve the standard first time. Try to find a operative who will stay on site and help find leaks. Agree with them to test, advise remedial and return for retest as one price. We needed two visits.

[Adokforme]

Air tightness is hard to achieve, especially with a revovation project (passive haus accept a lower standard for refurbs). Mine is a 1950s bungalow with brick cavity walls. For air tightness we replastered one coat externally, before 200mm insulation and acrylic render and connected the extenal wall air tightness line (wall plaster) to the roof air tightness line (OSB onto rafters, edges bedded in silicone - re-roofed the house at the same time. The problem with the test is the cost/visit if you don't (you won't) achieve the standard first time. Try to find a operative who will stay on site and help find leaks. Agree with them to test, advise remedial and return for retest as one price. We needed two visits.

Thanks kia456 that was some refurbishment undertaken there so hopefully well worth the effort of it all. Are you able to advise what airtightness figure you finally arrived at?
We've booked ours to test and stay on site for upto three hours in an attempt to establish other leaks with temporary fixes in the hope of arriving at before and after figures as a basis for deciding on whether to go ahead with MVHR.
All twelve downlighters are now sealed and I'll be working on ceiling light and switch fittings to hopefully capture one or two more prior to test. I think the cooker hood and bath extracts might need some attention knowing these would likely need replacing by the new system should we go ahead!

[kla456]

We got to 1 air change/hour and left it at that. Passiv haus standard of 0.6 is not expected for refurbs/retrofits.
For MVHR consider small in-the-wall room units - Fresh-r, DUCO, Renson make these in Netherlands. Well-suited to refrbishment projects - require no ducting - come with humidity/Co2 sensors. Try to attend a trade exhibition in Netherlands (they lead with small MVHR) eg. VSK Utrecht - mine were installed in 2014 - technology will have changed since then. Consider accessibility for annual cleaning (filters) and servicing. I have 3 Fresh-r units (+1 spare) in Scotland fitted into the external walls - but Fresh-r are a bit expensive. I would probably go for DUCO or Renson if replacing (because of price). Most are available through UK stockists.

[Adokforme]

1 air change per hour, that's really impressive, I shan't be attempting anything near that as from my limited understanding 3 to 4 would be the best we could hope to achieve without resorting to vapour proofing the walls amongst others.
Thanks for info on alternate small units as they're something that appeals also.