A builder’s net zero envelope course by Xerox Builders · October 2026
Good envelope details fail when they are built in the wrong order or damaged by the next trade. This Detail sets out a typical build order with hold points, the pre-construction meeting, who installs, protects and checks each layer, and how to plan repairs, photos and testing into the schedule.
Why the order matters
Most envelope details only work if they are built in the right order. A top plate pre-strip has to go on before the trusses, a sill pan before the window, a sealed penetration before the insulation. If one step is missed, the next trade covers it, and the mistake is hidden until a blower door test or a leak finds it. BC Housing’s airtightness guide makes the same point about testing: the later a problem is found, the harder and more expensive it is to fix.
A useful way to think about it is a relay: every trade receives the envelope intact and must hand it on intact.
A typical build order with hold points
For a wood-frame house with an exterior air barrier, a typical sequence looks like this. A hold point is a stage where nobody covers the work until it has been checked and signed off.
- Foundation: capillary break, sill gasket and membrane tie-in (Detail 05).
- Framing, with pre-strips at the top plates, rim joists and ledgers.
- Sheathing, air barrier membrane, and windows and doors.
- Roof on; roof-to-wall joints sealed (Detail 15).
- Hold point: membrane, windows and pre-strips checked; sample window hose-tested.
- Rough-ins: plumbing, electrical, ventilation and gas, with every hole sealed (Detail 16). Outside, strapping and cladding can follow once hold point one is signed off.
- Hold point: mid-construction blower door test with smoke (Detail 18).
- Insulation. Hold point: insulation inspection and interior seal check.
- Drywall and interior finishes.
- Hold point: final blower door test (Detail 19).
Your sequence may differ, for example with an interior air barrier or a different window approach. What matters is that it is written down and every trade has seen it.
The pre-construction meeting
Hold a meeting before work starts with every trade that will install, cross or cover the envelope, not only the site supervisor. Cover:
- The air barrier line on every drawing, and the critical details where it changes material or direction.
- Products, compatibility, primers and cure times.
- Who installs, who protects and who repairs each part.
- Hold points, inspection and test dates.
- How damage is reported.
BC Housing’s airtightness guide recommends these meetings include hands-on training, and recommends mock-ups of representative interfaces, tested and refined before the details are repeated across the building. On a house, building one tricky corner together on site is often enough.
Installs, protects, checks
| Layer or detail | Installs | Protects | Checks |
|---|---|---|---|
| Sill gasket and pre-strips | Framer | Framer | Air boss |
| Membrane and tapes | Envelope installer | Every trade | Air boss |
| Windows and doors | Window installer | Every trade | Air boss, hose test |
| Service penetrations | Each trade | Each trade | Air boss, smoke test |
| Whole air barrier | Everyone | Everyone | Energy advisor test |
The “air boss” is the term BC Housing’s guide uses for the one person on the construction team who owns the air barrier: reviewing work, tracking open items, coordinating tests and overseeing repairs. The builder remains responsible for the whole installation.
Protect, repair, record
Protect. Membranes have a UV exposure limit set by the maker (the BC Housing guide gives no single number, so check each product’s data sheet), so plan for cladding to follow in time. Fasten loose laps against wind. Tape and prime only on surfaces that are dry and warm enough. Scaffold ties, ladders, staples and signs all puncture membranes, and sill pans and thresholds get used as steps unless they are covered.
Repair. Walk the envelope at the end of each day. Patch with a compatible membrane or tape, well past the damage, lapped shingle-style with the top edge under the lap above or taped, then rolled firmly. Make it normal to report damage rather than hide it.
Record. Photograph every detail before the next layer hides it, with a label or tape in the shot to show location. File by date and wall or room, share with the energy advisor, and keep the set for warranty records.
Schedule implications
- Primers and cure times can mean two visits to the same area.
- Cold, wet weather affects adhesion and curing; allow weather days.
- Where possible, finish framing before membrane work, so trades are not working over each other.
- Install metal flashings after the air barrier is complete, rather than relying on them as part of it. Membrane sill pans still go in before the windows.
- Book blower door tests early, keep the site quiet on test day, and leave time to fix leaks and re-test.
Site checklist
- Written build order with hold points shared with all trades
- Pre-construction meeting held with every envelope trade
- Mock-up of a critical detail built and reviewed
- Installs / protects / checks list agreed
- Air boss named and known to every trade
- Hold points and blower door tests in the schedule; city notice given
- Daily walk for damage; same-day repairs
- Every detail photographed before cover-up
- Weather days and cure times allowed for
Test yourself
Try to answer each question, then click it to check.
What is a hold point?
A stage where nobody covers the work until it has been checked and signed off.
Who should be at the pre-construction meeting?
Every trade that installs, crosses or covers the envelope, along with the air boss.
When should a damaged membrane be repaired?
The same day, with a compatible patch lapped shingle-style and rolled firmly.
Next: Detail 18, Mid-Construction Blower Door Test. See also our Net Zero Homes page.
Planning a high-performance home in Vancouver, Burnaby or Surrey? Talk to our team about getting the envelope right from day one.