0.6 Ach50 (Air changes per hour at a pressure of 50 pascals)
We achieved "Passive House" levels of air tightness in our envelope.
As a reference point,
The building code requires a score less than 7.0
Energy Star Homes for Portland and Earth Advantage is less than 4.0.
Lower the better.
It was incredibly useful to do the preliminary blower door test months ago; without it, we would not have been able to identify and rectify a few key leaks in the envelope. Our results improved dramatically.
I would wholeheartedly recommend the preliminary test to anyone who wants to ensure best air-tightness results.