I've been asked to perform blower door testing on a house that is to be built.The architects builders estimate specifications state " Perform a blower door test on the house after the wall sheathing, rigid foam wall sheathing, roof sheathing, and windows are installed and sealed, prior to installing interior and wall insulation. Maximum 1.00 air changes per hour at 50 pascals. Perform another blower door test after insulation is installed." I foresee at least one big problem in that there will be air coming through the soffit and ridge vents without the ceiling being sheetrocked and I'm not sure if a maximum of 1.00 ach is possible to achieve. I'm hoping some one could direct me to a source of information on how to conduct this type of testing.

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Definitely a problem. If the house has a flat ceiling, then the best thing is for the drywallers to hang and tape the ceiling out of sequence, so that you're testing the ceiling, the wall sheathing w/ windows and doors, and the floor. That's what I did in my house, and it made for easy air-sealing. My drywaller is an understanding kind of guy.

If they won't hang the ceiling first, then you can theoretically seal the soffit and ridge vents (with what, you ask, to which I reply, I dunno) but then you are testing those seals as well as the roof deck. 

If there are cathedral ceiling areas, those most likely have to be insulated and rocked before your first test, or else the insulator has to install some bombproof baffles in every rafter bay.

All things are possible though that will be a very tough number to hit as David mentioned. Beyond that give them your rate per test & additional hourly for directed air sealing

Doing this test is the same as a regular one with the only difference being, you need to make sure the dryer vent & all other vents are taped off. I agree on the drywall approach assuming they are not going with a hot-roof style system

If that isn't possible - as for soffit & ridge - that depends on if they have finished the outside finishes or not. The ridge is easy as the tar paper or I&W can simply cover the gap & they can cut it out when they go to install the finishes. As for the soffit, it depends on the size & how they did it - you can use tape, staple up plastic, etc...

Thanks for the input. I've been searching the internet for the last few days and I found a local company's website called G*O Logic. They have been building homes using the Passivhaus as a reference. One video showed a blower door test done at the same point that the architect wanted me to conduct the test. What they had done was sheath the bottom side of the rafters with zip wall after insulating it. They then sealed the zip wall to the side wall vapor barrier and then conducted the blower door test. Its clear to me now that the architect I'm dealing with has no experience with this and I need to take a Passivhaus course if I'm going to be dealing with high efficiency homes in the future. By the way, they claimed to have achieved .4 ACH50. I didn't think this would be possible.

Well, it has everything to do with how much time and money you're given to set up and perform the test. If they want the ceiling completely masked off, or the roof venting sealed completely on a temporary basis... go for it... and bill them for it. Tell them you need the entire place to yourself, get a helper, go in there, set up everything you need, and then work like crazy to find every leak and seal it. It mostly takes time and persistence, and you can get down to the level they want.

I do it routinely for sprayfoam projects

1ACH50 ain't your problem...you are just a scorekeeper. If the subs whose trades involve air sealing haven't built to that level of tightness, they are in for a painful process.

Obviously you can't test a building with a vented attic whose ceiling is not in place...again, not your problem.

Establish a test charge, but also an hourly rate for standing by while other trades get ready or fix their screwups.

You may want to plan for temporarily blocking "normal" openings such as flues, vent fan caps, range hood, dryer exhaust. Don't forget plumbing stacks if traps lack water. Other than that, let it be someone else's war.



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