Still building our house. Finally did a blower door test. This is my builders first time trying to build super tight because he’s never had a customer who had an emphasis on it before.

We’re currently at 0.36 ACH 50. Given it was his first time shooting for something like that, I was going to be thrilled with anything under 1 so 0.36 is just amazing to me. I am super happy.

The rest of this is pretty long and totally unnecessary to read but if anyone wants the details of how the house is built, I figured I’d describe it in the original post so I don’t have to later.

House is on the Western edge of climate zone 5A in the USA, about halfway between the North and South sides of climate zone 5.

There really are no inspections (other than septic) in my area so not many people who build in my area care a ton about efficiency standards and various other things.

House has a little over a 2,100 square foot footprint and it has a full basement under the main floor.

Basement is a walkout basement and is an ICF basement.

Main floor is:

– 2×6 framing
– ZIP sheathing
– 2” external Halo Exterra (wanted it to be 3” of Rockwool comfortboard but availability was an issue)
– rockwool inside the exterior walls
– vented attic
– Advantage Architectural Woodwork Windows and doors (they build Smartwin products in the USA)

The biggest issue for us was trying to figure out how to get the air barrier transition from the walls to the ceiling to work well.

I still feel like I didn’t communicate my objectives well in that regard or something. My hope was to do something like what Steve Baczek and Jake Burton do which is to either:

– drape siga majrex over all walls before putting roof trusses up

or

– put ZIP sheathing over all walls before putting roof trusses up

then after the roof trusses are up, fill in the siga or the ZIP to create a continuous air barrier from the walls to the ceiling

Next, build a service cavity below the siga majrex or ZIP using 2×4’s

Run all electrical and lighting (wafer lights) in that service cavity so there are very few penetrations to seal with the air barrier.

None of that is what happened though. I feel that is because of a communication issue on my part. He went with the ZIP sheathing idea but he did it after the roof trusses were up and he did not make a service cavity. I kinda feel like since he did not make a service cavity he could have done the same thing with regular drywall maybe. He has many penetrations in the ZIP from installing can lights and various electrical penetrations and so on. He also had lots of things that needed sealed where the ZIP was against framing but he was extremely fastidious in doing extra air sealing on the can light fixtures and all of the ZIP against various framing members.

I feel the way he did it was a LOT more labor and still as much materials as other methods that would have been less labor but who am I to complain with the final results of the test? Plus I feel pretty ecstatic that I can just change lightbulbs in can lights instead of change entire wafer lights and possibly not have the same style available and not have matching lights at some point in the future.

I guess what I’m saying is I’m pretty ecstatic with the results. I suspect there are not many vented attic houses with can lights that have a better blower door test.