How do you attach exterior siding without affecting the air barrier on a passive house?

Scott Bowker July 16, 2018Updated: July 30, 2020

I'm using the "Zip system" of exterior cladding. Over this I plan to install 6" of iso foam, for additional insulation, and siding over the foam.

I'm unsure how to attach anything to the "Zip system", without penetrating the airtight barrier.

Thanks, Scott

Responses (3)

Anwas Qwelten 3 years ago

I am also wondering about the fasteners into my air barrier for exterior insulation and the siding.  Are you saying that it is not necessary to use the pieces Flexxband where penetrations go into the air barrier?  That would certainly make life easier.  I'm also wondering about using a trowel on air barrier.  Don't see any information on your site about this:  Is it a good option.  The Delta Vent SA is too expensive for my project.  Any suggestions are welcomed.  Many thanks!

Ecohome 3 years ago

Hi Anwas, 

Where you saw us putting pieces of Delta Flexxband where screws would go was a bit of overkill in our opinion. We had the product, and the manufacturer suggested trying it, but it is not something we think is really necessary. 

About trowel-on air barriers, we haven't had any experience with that so we aren't in a position to answer either way, sorry.  As for your budget, remember that the most important factor that will make or break an air barrier is attention to detail. Even in homes where something as basic as standard building tape and 6 mil poly are relied upon to act as the air barrier, they can have wildly different results depending on the care with which they were installed. 

We prefer high quality tapes and air barriers that adhere to a substrate, but whatever membrane you apply and tape you choose, just be very careful during installation. Be careful not to puncture it, and when you do, be sure to tape it. Try to avoid areas where mebranes are folded over, and when you do have to fold it, take great care to tape it well as it is a very common spot for air leakage.