8 Steps to Guide Airtight Construction a.k.a. How To Keep It Tight
Constructing an airtight building should be pretty straight forward. To help ensure the best possible execution there are several steps that should be taken both before and during the construction process.
- Provide clear and comprehensive air sealing details to the contractor.
- Provide a clear and comprehensive 3-part specification document to the contractor.
- Notify the entire construction crew including the subcontractors, at the very start of the project, that the building has an air-tightness goal and will be blower door tested.
- 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.
- 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 airbarrier.) 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.
- 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.
Posting from Farbrica718 Passive House project, which helped it hit 0.4ACH50
With these measures, fewer unpleasant surprises will take place when blower door testing, and greater success in achieving your airtight goals will be met.
Keep it tight.