Airtightness Performance on Green Star Projects Starts With Trade Coordination
Key Takeaways
Airtightness isn't owned by one trade. Electricians, plumbers, fire contractors, mechanical contractors and façade installers (and many more people) all create penetrations in the envelope.
Every penetration is a potential leak point, and every trade that creates one is responsible for how it's sealed.
Green Star targets raise the stakes, because the performance threshold leaves far less room for uncoordinated gaps.
Coordination matters more than any single trade doing a perfect job in isolation.
Airtight buildings are built by teams, not individuals.
Ask most people on site who’s responsible for airtightness, and they’ll point at the testing contractor. That’s the wrong answer.
By the time the blower door shows up, the envelope’s performance has already been decided by EVERY trade who never thought of themselves as being in the airtightness business.
Airtightness Isn't Owned by One Trade
Airtightness isn’t owned by one trade. It’s the sum of every penetration, junction and service run that passes through the building envelope, made by whichever trade happened to be on site that week.
That’s the part that gets missed on most projects. There’s no single trade whose job title includes “seal the envelope.” It falls between everyone, which means it’s easy for it to fall through the cracks entirely unless someone is actively coordinating it.
Every Penetration Is a Risk Someone Has to Own
Electricians
Every conduit run, switchboard penetration and cable entry through an external wall or ceiling is a potential leak path. Multiply that across a commercial fitout and the number of penetrations adds up fast. When cables run through plasterboard, how they’re sealed and at what separation gaps is critical to design and testing success. Aerotight works with Electricians to learn and implement best practice.
Plumbers
Pipe penetrations for water, waste and gas all pass through the envelope somewhere, often through the same cavity or slab, which makes sequencing and access harder to manage cleanly.
Fire Contractors
Fire-rated penetrations and collars have their own compliance requirements on top of airtightness, which means the sealing detail has to satisfy two standards at once, not just one. Aerotight is constantly taking photos on site of good and bad examples, giving builders feedback on getting subcontractors back to seal and finish the job properly. Or if not, deducting the final invoice to that subcontractor for not doing their job properly the first time.
Mechanical Contractors
Ductwork, louvres and plant penetrations are often the largest single openings in the envelope. A mechanical contractor who isn’t thinking about airtightness can undo the careful work of every other trade on the job including themselves. Leaving appropriate and necessary gaps from ceilings for ductwork, vents etc – is critical to ensuring all penetrations can be properly sealed.
Façade Installers
Window-to-wall junctions, cladding interfaces and movement joints sit right at the edge of the air barrier. Get the membrane continuity wrong here and it’s one of the hardest defects to fix once the façade is closed up.
Why Green Star Raises the Stakes on Coordination
A standard build has some margin for a missed seal here or there. A Green Star target usually doesn’t, or at least not multiple times across the building envelope. The performance threshold that earns the rating points leaves far less room for the kind of small, uncoordinated gaps that would barely register on a conventional project.
That means the coordination problem that exists on every job becomes a compliance risk on a Green Star job. It’s no longer just about comfort or energy bills, it’s about whether the rating is achievable at all.
Good Coordination Beats Good Intentions
Every trade matters, but coordination matters even more. A brilliant façade installer working next to an electrician who has never been briefed on the air barrier still ends up with a leaky building. The fix isn’t better individual trades, it’s getting everyone aligned on the same strategy before they start cutting into the envelope.
That’s exactly what trade workshops are for: getting every trade on the same page about where the air barrier is, why it matters, and what a compliant penetration actually looks like, before it becomes a defect that shows up at final testing.
Airtight Buildings Are Built by Teams
Airtight buildings are built by teams, not individuals. No single trade can deliver a Green Star airtightness result on their own, and no amount of skill from one contractor can compensate for five others who were never briefed on the strategy.
Coordinate the trades early, using our 8-step airtightness process to keep everyone aligned from design through to final verification under AS/NZS ISO 9972, and the test at the end stops being a gamble. It becomes confirmation of work that was already done right.
If your project is heading toward a Green Star target, talk to us about coordinating your trades before the envelope closes up, not after.
Frequently Asked Questions
Who is ultimately responsible for a building’s airtightness performance?
Airtightness is a shared responsibility across multiple trades, not a single contractor. While the principal contractor oversees the overall target, electricians, plumbers, fire, mechanical, and façade installers each own the integrity of the penetrations they create in the building envelope.
Isn't the testing contractor responsible for ensuring the building is airtight?
No. The blower door testing contractor only measures the final result under standards like AS/NZS ISO 9972. By the time final testing occurs, the building envelope’s performance is already locked in by the work done earlier by each subcontractor.
How do non-façade trades (like electricians and plumbers) impact airtightness?
How do fire compliance and airtightness work together at penetrations?
What makes mechanical and façade penetrations particularly risky?
Ductwork, louvres, window-to-wall junctions, and cladding interfaces represent some of the largest openings and perimeter joints in the envelope. Defects or membrane gaps at these locations are exceptionally difficult and costly to fix once the façade is closed up.
Why is airtightness trade coordination critical for Green Star projects?
When is the best time to coordinate trades regarding the air barrier?
As early as possible – ideally during early design and pre-construction phase via trade workshops. Briefing trades on the air barrier strategy before they start cutting into the envelope prevents costly rework and defects later.
How does early trade coordination de-risk the final blower door test?
Other Articles You Might've Missed
Airtightness Compliance: Visual Inspection Isn’t Enough
How to Seal Slab Edges Properly (Avoid First Pass Fails)
What Make-Up Air Design Is Actually Trying to Achieve
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