Aerobarrier timing question
My wife and I are building a home and have tried to educate ourselves on building science. We’re building a ranch home in Nebraska with approximately 3600 square feet of conditioned space. Our builder is averaging about 2 ACH50 for the enclosure. I was wanting less than 1.5 so I proposed aerobarrier to go for 1 ACH50. The aerobarrier contractor in our area said we should apply post drywall. But all I’ve heard is that you should apply to your primary air barrier. In our case, that’s the zip sheathing and drywall on the ceiling. I’m not a builder, so I’m not sure the best approach. Should I spend the money to do this? If so, should I push to apply to the primary air barriers?
Thanks,
Matt
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Replies
The issue is that it could end up costing a lot more, depending on the builder's attention to details. When you apply pre-drywall, more material ends up getting wasted filling up relatively large holes, and it takes more time.
If you want to apply to the "primary air barrier" in your case, you'd have to convince the builder (who would have to convince the drywall sub) to do the job in two phases, which will raise the cost.
Aerobarrier finds leaks and fills them. It doesn't care what you have designated as the primary or secondary barrier.
You do understand what you are asking the contractor to do is come in early with a small drywall delivery get the dry wall crew in to install just the ceiling get it taped and a coat of mud by another crew. That adds up to a lot costs and hassles for little benefit the hole point of Aerobarrier is that it is a low hassle air sealing.
I don’t see the point of wasting goodwill and money changing the order of operations when it will have zero affect on how tight the finished home will be.
Walt
We had the local AeroBarrier distributor air seal our (under construction) new home after all drywall was installed and taped (windows and doors installed), but before any interior finishing was done. That took us down from about 1.5ACH50 to less than 0.8ACH50 in about two hours. Easy-peasy, cost was very reasonable (less than $1.25/sq ft), and we're very happy with the results.
This came up in a recent conversation on the Passive House Accelerator (https://bit.ly/3DzNSz6) focused on AeroBarrier.
Basically, you can do it before drywall, as long as you're finished with your major penetrations. If, as you say, you already have the major components of your envelope in place, fenestrations installed, and exterior penetrations sealed up, you don't need to wait for any certain interior finishing steps. The interior drywall, in this case, becomes decorative, not part of the performance.
But you should definitely do it before the finished floor, because it will cover every horizontal surface. Masking the entire home is a hassle, needless to say. I think you're on the right path, but as others have remarked, you are now having a second drywall-installation phrase, which might be more expensive and harder to schedule.