You framed it tight. You sealed everything you could see. You passed your inspections. But the blower door test says otherwise.
If you’re building homes in British Columbia, you’ve probably run into this before. Step Code 4 and 5 require air sealing to a much higher standard. Even a small oversight can cost you a retest, a delayed handoff, and a frustrated client.
Air leakage isn’t about big mistakes. It’s about small, overlooked ones that add up.
Air leakage is uncontrolled airflow through gaps, cracks, and holes in the building envelope. It can happen in places you don’t see: top plates, rim joists, electrical boxes, behind bathtubs, around recessed lights.
Every hole drilled for plumbing or wiring is a potential leak. Every penetration you miss during manual sealing lowers your airtightness score.
Most builders rely on spray foam, tape, and caulk to seal these gaps. That approach only works if every crew member is consistent. In practice, sealing by hand leaves a lot of guesswork on the table.
Builders sometimes ask whether duct sealing or envelope sealing is more important. The answer depends on the goal—but in most cases, you need both.
Envelope sealing targets the building shell—walls, ceilings, floors, and any gaps that connect indoor and outdoor air. It’s key to controlling air leakage and meeting blower door test results, especially for Step Code compliance.
Duct sealing focuses on the HVAC system. It prevents conditioned air from leaking into wall cavities, attics, or unconditioned spaces. This is especially important when ducts run through mechanical chases, floors, or crawlspaces.
Here’s the practical difference:
Envelope leaks affect the overall building seal and your ability to pass airtightness tests and meet code.
Duct leaks affect HVAC performance, room-to-room comfort, and home energy use.
Up to 30% of heated or cooled air is lost in typical duct systems before sealing. That leads to oversizing, uneven heating, and unhappy homeowners.
If you’re building homes with heat pumps, HRVs, or zoned systems, duct sealing helps those systems perform as specified.
For new construction, sealing the envelope at pre-drywall and the ducts after HVAC rough-in creates the best performance outcome.
Airtight Solutions now offers both services, so you can handle it all in one scope.
If you’re aiming for Step Code 4 or 5, you’re being measured. Blower door testing isn’t optional. Missing your target means calling trades back, delaying move-in dates, and explaining the issue to clients.
Aerosol building sealing typically improves ACH50 results by 50% or more. Builders have gone from 3.5 ACH50 to under 1.0 ACH50 in a single day.
Air-sealed homes lose less heated or cooled air. That means mechanical designers can size down the system, which reduces capital costs.
If you’re building high-performance homes, you’re likely integrating heat pumps or HRVs. A tight envelope helps those systems perform as designed.
Drafts, uneven room temperatures, and moisture issues often trace back to air leaks. Fixing these after the fact is expensive and time-consuming.
Clients won’t see the building envelope. But they’ll notice when their home feels comfortable and quiet—and when it doesn’t.
Delivering airtight homes builds trust. Your clients don’t want to talk about blower door results. They want a house that works as promised.
Pre-drywall is the best time to seal a home. Framing is complete. Mechanical rough-ins are in. There’s clear access to all the critical leakage points.
Some builders try to seal at multiple stages: framing, mechanical, insulation, drywall. But every additional step adds time and cost.
Aerobarrier sealing happens once, in a single day, and doesn’t rely on manual application. It’s computer-controlled, so you get real-time data showing exactly how much leakage is being reduced.
Airtight Solutions uses Aeroseal technology to seal the building envelope from the inside.
We prep the space, pressurize it, and release a water-based sealant into the air. The sealant particles automatically find and seal leaks as small as a human hair.
You get a printed report showing the leakage before and after sealing—no guesswork.
The process takes four to six hours. Your team doesn’t need to be on-site, and you can schedule it between inspections and insulation.
If you’re building to meet the BC Step Code, air leakage is your problem to solve. Doing nothing increases your risk. Doing it the old way increases your cost.
Want to see what Aeroseal can do for your next project?
Reach out to Airtight Solutions for a walkthrough. We’ll show you how to plan for airtightness early, hit your targets, and deliver better homes.
No guesswork. No delays. Just guaranteed results.
Proudly serving Greater Vancouver and Sea to Sky Corridor, British Columbia!