When Is the Best Time to Air Seal?

CodeWatcher best time to air seal

Home builders may need to rethink their approach to air sealing to meet new airtightness levels.

According to Home Innovation Research Labs’ recent Builder Omnibus Survey, air sealing ranks number four among a list of 18 top challenges for builders in meeting current energy efficiency requirements for new homes. Roughly 10 percent of builders reported difficulties meeting new airtightness levels.

With contractors playing a significant role in helping builders reach these targets, is it time for home builders to reconsider the best time to air seal a new home? Michael Schettine, president of Schettine Associates, the manufacturer of Accuframe, believes builders must rethink their approach to air sealing to ensure success.

Builders Must Manage Air Sealing

According to Schettine, builders must become familiar with the top air leakage areas in new home construction to address these locations. “First, to address compliance the builder needs to identify and block leakage points,” he says. “Wood-to-wood connections cannot halt air intrusion when the structure is pressurized during heating and cooling cycles. If builders want to get to the point where they reach first-time compliance with air tightness testing, these open gaps can no longer be ignored.”

As we previously reported in an earlier blog post, up to 50 percent of builders in states that have adopted the 2012/15 IECC fail the initial blower door test for air tightness. Schettine asserts that the failure rate could be cut significantly if builders took a different approach to air sealing by re-claiming the air sealing responsibility.

“Just a couple of decades ago, builders had responsibility for everything from footing forms to hanging crown molding,” Schettine notes. “Today, for various reasons, builders have generally migrated to a subcontractor model to manage the building process. In comparison, the historical model was profitable and allowed the builder more control over the process with less reliance on multiple contractors to complete their specific jobs. With the existing subcontractor model, all it takes is one bottleneck from one subcontractor to cause a cascade of delays that can seriously affect profits in a negative direction. Today’s tight labor market only exacerbates the problem because of the increased time needed to locate a subcontractor to step in if another isn’t working out and as we know, time is money.”

Builders constantly assess the hard management costs to a subcontractor model, but that model is riddled with costs and complexity – especially when it comes to scheduling and quality control. “A growing concern for me is that builders are relying on the insulation contractor to attain air sealing compliance, but is that wise?”

Schettine argues that builders should instead have a dedicated two- or three-person team whose purpose would be code compliance. This team would be responsible for working with the framer to achieve air tightness in new homes rather than delegating this responsibility largely to the insulation contractor.

The Best Time to Air Seal

Many energy-efficiency advocates will tell you that framers arguably play the largest role of any subcontractor in constructing an airtight, energy-efficient home. Schettine says framers should be air sealing the home so that builders can optimize the airtightness levels.

“Builders need to focus on cost-effective ways to reduce air intrusion before insulating homes and this logically falls to the framing phase to air seal gaps,” Schettine says  (see video). By re-assigning the air sealing to the framers, Schettine argues that builders can choose cost-effective insulation following the application of air sealing in the framing process to address the top air leakage points and keep a line on costs.

“I often ask builders if they’re caulking inside framing gaps to stop conditioned air from leaving the conditioned space or to prevent unconditioned air from entering the conditioned space and naturally, most say both. Then I point out that air entering the conditioned space has already diminished the building’s insulation value,” he said. “The benefit of framers handling the air sealing as they are framing the home is that once that job is done, the majority of your air sealing labor is complete, and the insulation can be installed.”

Radically Different, But Fundamentally Better

Schettine says the new air tightness requirements mean the framers’ role is more important than ever. A builder who chooses to have a code compliance team work directly with the framers to ensure proper air sealing during the home’s framing stage should be able to meet the new blower door test requirements the first time, thereby reducing the need for remediation to correct air leakage issues.

“Most of the energy rating companies I’ve spoken with estimate the initial blower door test failure rate at 40 to 50 percent for new buildings in the colder Climate Zone 3. To meet the more stringent energy compliance standards of today, the value of proper air sealing is readily apparent, and the methods used should be determined as the builder re-evaluates the best approach for success.”

As builders across the country construct new homes that are increasingly airtight and energy efficient, keeping a line on costs is also important. In air sealing during the framing stage, Schettine says builders can not only regain some control over quality assurance by having their code compliance team work with the framers on air sealing, but also keep costs in check.

“The benefits of successful air sealing have a multiplying effect. Less time scheduling, lower installation costs, less expensive air sealing strategies, and fewer contractor bottlenecks will add up to more control and greater profit in the long run.”



2 Comments on "When Is the Best Time to Air Seal?"

  1. I agree that much of the air sealing can be done by the framers, however the area that they are not typically involved in is the ceiling drywall / framing leaks. I’ve noticed many new homes have leaks at many wall top plates as well as poorly sealed plumbing and electrical openings (typically builders in my area rely on those trades to do their own sealing). What I’d like builders to do is to do away with using plastic sheet vapor barriers and fully air seal attics – as we do with existing older homes. Spray foaming EVERY opening on an attic floor is much more effective than spot air sealing, but the plastic needs to be gone for proper adhesion of the foam to the drywall. It is acceptable to use vapor barrier primers/paints as long as the building officials sign off on it – at least here in my area (Wisconsin).

    • Mark:

      Your last sentence brings up a great point: There are a lot of things, not present in the code, that are acceptable as long as building officials approve it. They usually want to see some 3rd party documentation that the claims are substantiated. It’s a CYA measure, to be sure, but a small price to pay for having them sign off on something not explicitly approved in the governing code of the jurisdiction.

      Mike Collignon

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