Many of our colleagues wondered why we decided to run a test so early in the construction process. Usually this kind of assessment is made after the windows and doors are in place, and after the roof is complete. In that scenario, however, it would be already too late to address air infiltration in areas of the thermal envelope that are covered with insulation, such as external walls, roof, and delicate envelope intersection points (wall to roof; wall to window etc.).
We decided to run the test early, so that we could identify any air leaks and fix them before finishing the roof. Our team* (basically any subcontractor whose work penetrates the building envelope) was assembled and present for the test, ready to address any air leakages present in their work. We were sealed inside while our colleagues Cristian Guida and Gianni Giavarini (from Oikema) set up and executed the Blower Door Test and took the infiltration measurements.
The main challenge of doing this, we quickly discovered, is that in order to get the correct amount of pressurization inside the house, the temporary coverings over the windows need to be fixed fairly well (which they were not). We had a few pop out the first time we ran the fan, but they were quickly reinforced and checked for any holes. Instead of pressurizing the whole house at once, we separated it into zones (this was made easier by the way this particular house was designed). In this way, we could go upstairs, seal half of that floor, run the Blower Door Test, and go around and check where each rafter met the collar beam.
In the roof, we found some infiltration at the corners (the weakest spot for airtightness), and around some pipe crossings. There was also some evidence of air movement at the ridge beam. However, we later attributed this to air passing between two rooms. Most of the rafters read a negligible level of air movement. Once we identified which ones needed to be sealed more, our roofer was on the job immediately, taping up any small holes. The hydraulic and electric openings were checked for air leakages as well, with minimal fixes needing to be made.
While an early test like this one is not required for CasaClima certification (or Passive House), we felt that it contributed greatly to our understanding of vulnerable points in the building envelope for air infiltration. Now, before proceeding with the completion of the roof, a second pass will be made over these points. Down the line, at the completion of the construction site, another Blower Door Test will provide the numbers that will qualify the construction for its CasaClima Class A certification. To learn more about CasaClima, please read our articles on this blog and subscribe to our newsletter.
*A big thanks to the members of our project team who helped out Friday: contractor (Nicola Lucci of Montanari Luigi), bricklayers (Tabba, Ali, and Assran), electrician (Massimo Malvisi), plumber (Davide Morini), window and door installer (Maurizio), roofer (Pierluigi Confetti of Confetti Legnami), and Blower Door Testers (Cristian Guida and Gianni Giavarini from Oikema)