Aerobarrier experience and opinions
Kamm7482
| Posted in GBA Pro Help on
I’m wondering what experience folks here have with using Aerobarrier for air sealing the interior side of a new wall. I’m nearing the phase of a new build where I need to decide if Aerobarrier is worth the money or if other interior air sealing methods are better and/or more cost effective. My goal for air tightness is below 1ACH 50 – the Aerobarrier rep in my area says that is easily achievable and has quoted approx. $1.50/sf to get those results. Any experiences and advice is appreciated.
Thanks,
Brandon
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Replies
I would change your goal to 1ACH@50, even years after the test. But there seems to be little data on how air sealing methods hold up over time.
Hi Brandon,
To air seal a house to or below 1ACH50 typically requires series of steps and important details from the slab to the ceiling (or roof). Single materials detailed as air barriers often \seal large portions of the building. For example, the vapor retarder under the slab can have taped seams and taped or otherwise sealed edges to be air tight and the sheathing can be detailed at the perimeter and seams to be airtight. Same with the ceiling inside.
But even with these large areas taken care of, the transitions in materials is ultimately important, the foundation wall-to-floor transition, the transition from the exterior sheathing to the interior ceiling at the upper floor top plate. And of course all penetrations need to be diligently air sealed including windows and doors, plumbing, and electrical penetrations, etc.
We know that AeroBarrier works (unfortunately, I'm not aware that we know how long any of this air sealing lasts, as Jon pointed out), but I'm not sure I would skip any of the air sealing that I mentioned above and rely on AreoBarrier. These details are cost-effective and they are often amount to paying just a bit more attention to things you have to do anyway, like install a sub-slab vapor barrier, sheathing, a WRB, a ceiling, etc. With all that done, you won't need AeroBarrier, though you could decide to use it to tighten the house even more, if you wanted to.
Would you say that a modular construction plan from a company who actively strives for net zero builds that’s planned to blower door test at code 3 ach50 but uses Aerobarrier to get it down to 1.5 ach50 is legit? Would I be able to tell if they’re cutting corners in the control layers and joints/transitions? I feel like I’d like it to be better than code air sealing without this new thing Aerobarrier.
Brandon,
We're currently building a passive house in SLC. Our builder paid attention to air sealing details throughout the process but was struggling to get it to 0.6 ACH@50. We did aerobarrier and that got us to ~0.4ACH@50 before we put insulation in the walls. The house isn't finished yet so I don't know about longevity but it worked well in getting to passive house standards.
Scott
Even if the air sealing starts to degrade over time, it’s still better than it you’d done nothing. The example I like to use is a caulked gap: even if the fail eventually separates one side, it’s still blocking a big chunk of the gap and reducing the overall open aperture that can leak. Degraded air sealing materials are still going to be at least partially effective for a long period of time.
I wouldn’t skip the air sealing details due to concern that it will degrade over time.
Bill
This is easy- if you spent the 1.50nsq foot on detailing, etc. what would it buy you? Teh value of aero barrier rises as the level of meticulous detailing declines. Paradoxically, aerobarrier is heaven for production builders, esp when they can just throw fiberglass batt on afterwards. The real sweet spot for aerobarrier is when you get ‘custom’ builders who are not passive house anal but charging clients top dollar. For $6000 you get a guaranteed tight house, well on the way to a comfortable house That’s like what 0.1% cost of the entire build ?
Yeah, this modular company I’m considering builds for net zero but it seems like their loads in their houses aren’t managed that well if they’re built to code 3 ach50 and then rely on aerobarroer after the drywall and lots of finishes I believe too is attached in the factory before it ships to the site to be put on the foundation. I guess I need more details about how they’re connecting all the joints and transitions. I’ll try to find their house plans with those details but is finishing a house to code 3ach50 with pretty good exterior and total insulation levels and positioned the right way on the land etc and then finishing off with Aerobarrier to increase the air tightness by 2x something one should be skeptical of from a building durability standpoint as well as an efficiency one?
I recently did Aerobarrier and I was pleased with it. Project was a mostly new house, but due to environmental concerns on the site it had to be built partly on a century-old foundation and partly on helical piers. Because of the way the foundation was we were concerned that it would be difficult to get complete air sealing.
Before sealing the house tested at 4+ ACH50. After sealing it was 1.4. The sales rep had said the same thing that we should be able to go as low as we wanted, but after nine gallons of caulk were pumped into the house the technician said it had stopped improving. Cost was about $3500. We did the sealing after drywall but before any interior finishes.
The sales rep said most of his calls are either new construction that has failed a blower door test, or condominiums where a neighbor smokes cannabis, which is now legal in DC.
That’s great personal experience, thank you. I don’t love the air control layer being inside at the drywall though. Isn’t it better to be at the exterior perimeter? In my possible case at the moment the modular company build has air and water control layer at the sheathing and it’s built to the 3ach50 code. I’d feel better about it if Aerobarrier was used before drywall so it was part of the main air control layer at the sheathing. Stuff is great to seal up existing places for sure but for a new build (modular) in this case, what do you think about Application after drywall is up?
Your instinct is correct. Seal BEFORE gyp board. My house uses gyp board as its air barrier, and every time I hang something on the wall I'm penetrating the air barrier - stupid system, and one of those "I wish I had known then what I know now" things.
It has to do more with construction phasing. We did an unvented roof on the top floor so the HVAC went in after the insulation. Guys were still making holes in the building envelope up until the drywall went on.
For sure do it before drywall ; installers prefer AFtEr drywall, but remember , you are paying the bill.