Insulation Institute has been focusing of late on the topic of air sealing and what it takes to construct a home that is airtight using the “3 Ps,” -- People, Practices and Products. Proper air sealing is critical for meeting stringent air change rates required for green building targets such as HERS, Energy Star, Net Zero or Passive House. While there’s a plethora of guidance available on air sealing from many sources within the building industry, the best guidance to convey to the various contractors involved in home construction can be distilled to this: air seal “like a boss.” That is to say that everyone involved in the construction of that home has a role to play and their role should not be viewed as that of a “jobber” but a “boss” when it comes to air sealing, because getting to stringent targets requires that one think “holistically” versus individually.
Among the many admirable traits great bosses have are a few that are particularly applicable to quality air-tight construction and the work of contractors. Being a “boss” means you:
- Communicate goals and expectations clearly
- Properly train employees so they know the right way to do the job
- Ask for feedback from the team when explaining goals/targets
- Expect the best
John Druelinger is a Certified Passive House Consultant and Creative Director for 475 Performance, a high performance building supply company based in Brooklyn, NY. Druelinger also believes that air sealing is everyone’s responsibility and he’s not alone. In dozens of presentations and conversations with building industry professionals, it’s clear that getting an air tight building should be fairly straight forward, but the devil is in the details.
Ensuring an air tight building assembly, according to Druelinger requires that builders take the following actions. This list focuses on two of the three “P” categories – people and processes.
- Provide clear and comprehensive air sealing details to the contractor.
- Provide a clear and comprehensive 3-part specification document (general, products, execution) to the contractor.
- At the very start of the project, notify the entire construction crew, including the subcontractors, that the building has an air-tightness goal and will be blower door tested.
- Identify all services coming in and out of the airtight building envelope (water, sewer, electric, HRV in and out, solar?) at the start of construction. (See this blogpost about sealing holes in your air barrier.) Too often last minute, unplanned penetrations for utilities (solar installers, cable/phone companies, etc.) can degrade the airtightness of a building by as much as 20% – which can easily mean the difference between meeting airtightness goals and missing them.
- The superintendent of the job (or other designated person with authority) should be responsible for maintaining the airtight layer – and should be the ONLY one allowed to approve any penetrations (cutting, drilling…..burning (watch out for those plumbers)) of the airtight membranes, plywood, OSB or plastered surfaces.
- Place clear airtight construction site signage throughout the job site reminding the crews that this is an airtight building and therefore the airtight control layers are not to be compromised with their work. If any cuts, holes or other penetrations are discovered they should be reported to the supervisor and repaired.
- Visually inspect the interior and/or exterior air-barrier as the work proceeds – have any apparent damages to the airtight layers reported and fixed.
- Translate the signage and other document text when necessary.
Employing these techniques allows 475 to consistently meet very low ACH50 levels, often well under 3 ACH50 and in many instances below the passive house target of 0.6 ACH50. They also do all of this without using any sprayed foam, either canned or actual spray foam insulation (that’s the products piece). If your goal as a builder is reaching a specific green building target, these measures will ensure that there are fewer unpleasant surprises when blower door testing, and greater success in achieving your air leakage goals.