GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

How will drywall affect blower door test results?

user-1017420 | Posted in Energy Efficiency and Durability on

Good Morning all,
We are in the process of building a bio-compatible house in the Piemonte region of Italy. It is a double frame house (about the 2000 sq ft), with fully insulated 14″ walls. We hope the house will be certified CasaClima Gold Plus(kind of like PHI). We have completed all framing, 80% insulation, Vapour barrier, windows, doors. All services are installed, but not drywall.
The cost of doing Blower Door Tests here is very high, so we invested in a tester ourselves so we can monitor our progress, and when the project is done, we’ll go do blower tests around the countryside.
Anyway, we ran the first test yesterday, and obtained what everyone tells me is excellent. A 1.32 ACH50. However, this appears to be a long way from the 0.6 that I need for CasaClima Gold.
I have chased around the house looking for that “smoking gun” hole that explains where the air is coming from, and have determined that it probably doesn’t exist (all penetrations have been checked). It appears to be many very small areas that I’m not sure are easily fixed, short of foaming the inside of the house, which we would prefer not to do, hence the “bio” house. We have used no foams or chemical insulations to this point, only non-formaldehyde fiberglass insulation and perlite.
So my question is this. Given the level I am at now (1.32), what can I expect to see if the inside were completely drywalled (taped and mudded, but NOT ADA)? I should also mention that the exterior wrap is NOT complete, so not sure what the effect of this will be when done.
I am trying to determine if is it worth (or necessary) chasing all these ghosts.

Thanks for everyone’s time.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    OK, so you can't use spray foam. Are you allowed to use caulk? Or gaskets?

    I don't know how you can hit 0.6 ach50 if you aren't allowed to use caulk or gaskets.

  2. user-1017420 | | #2

    I would think that caulk is acceptable. It's not really a synthetic insulation, nor is it a pcv related product. As for gaskets, not sure what they are made of, and the bigger problem is that we have no source for that type of product here.

  3. GBA Editor
    Martin Holladay | | #3

    Well, if you want to hit your airtightness target, you should embrace the airtight drywall approach. And if you can't get gaskets, you need to become familiar with caulk.

  4. user-1017420 | | #4


    As Teal'c of Stargate SG-1 would say...."indeed".

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |