How GO Logic’s Shop Passed a Blower Door Test — Even with Giant Overhead Doors
As a companion to a recent Instagram post shared by Ben Bogie / Fine HomeBuilding about our new panel shop, this article dives deeper into the technical side: how we passed a blower door test — even with four large overhead doors.
When we unveiled our new GO Logic panel shop, one of the most common skeptical reactions was: “How in the world can this building pass a blower door test with four large overhead doors?” It’s a fair question. At 14,400 ft² with 23‑ft walls, and four big garage doors (8×10, two at 16×14, and one at 18×16), there’s a lot of potential leakage surface. But we did pass—Phius certified—and the building performs like a “shop you’d want to work in.”
Here’s how we did it (and why it works in practice).
The Basics: Why large doors pose a challenge
Large overhead doors are, unsurprisingly, among the most leakage‑prone components of a building envelope. They tend to have:
Long seams where panels meet,
Joints that must move (hinges, tracks, rollers),
Weatherstripping is often a compromise between durability and tightness,
“Stop” clearances (space between the door edge and the jamb) that must allow movement,
Pressure and deflection effects (wind, suction, etc.).
In a building of GO Logic’s size, even modest leakage per linear foot becomes significant in total cubic feet per minute (CFM). So the key is: making all the rest of the envelope as tight as possible, and specifying doors that are better than typical.
What we had working for us
High‑performance insulated doors
The doors we chose are CHI commercial insulated sandwich doors, 26‑gauge steel, 3" thick, with claimed R‑27 performance. Alan (in his transcript) noted that the spec sheet claims “R‑27 in three inches,” which is a bold claim (though reality may be somewhat lower under real conditions).
Manufacturers like CHI offer “insulated sandwich” commercial doors that, in their literature, reach R values up to ~26.89 (for 3" thick) in ideal test settings. That gives the doors a fighting chance of achieving low thermal losses (relatively speaking) and reducing temperature differentials across the door skins. (Coincidentally, the walls of the building achieve about the same R value).
Upgraded weatherstripping, adjustment, and sealing detail
The doors include a vinyl weatherstrip and a thick brush weatherstrip (on the exterior). Alan notes that the brush alone wouldn’t do much, but in combination with tight tolerances, they worked. When closed, the door panels are pressed tightly against that weather strip (which was adjusted during installation).
The tracks were carefully aligned so that the door closes at just the right position to compress the seals, reducing leakage. That kind of craftsmanship in field alignment makes a real difference.
In the blower door tests, the largest leakage in the envelope was around those doors—but (crucially) not enough to push the overall leakage rates out of compliance.
A super-tight envelope everywhere else
Because the doors were the “weakest link,” the rest of the building had to be airtight. In our case:
The walls (2×8 engineered studs, 23 ft tall) are insulated with dense-pack cellulose to near parity (or better) with the door R-value.
The ceiling received a continuous layer of Class II vapor barrier membrane, which also served as the air barrier with taped seams.
The continuity of the air barrier at critical junctions (walls-to-ceiling, slab edges, door frames, etc.) was carefully maintained to minimize leakage in those areas.
In other words, we minimized leakage everywhere else so the doors did not dominate the total CFM leakage.
Beneficial behavior during pressurization testing
Interestingly, the building fared better under pressurization (positive pressure) than under depressurization in the blower door tests. Because the doors are pressed against their seals/stops under positive pressure, leakage is reduced. In negative pressure mode, any gaps get “pulled on” more, increasing leakage. Alan noted that the pressurization test “performed a little better, which makes sense,” given this effect.
Real use behavior, moderate door opening
Day-to-day, the shop isn’t operated like a garage that opens constantly. The doors are typically closed, so their leakage is mostly “standing leakage,” not dynamic. Even when opened, the transient losses are tolerable, given the building’s thermal mass, interior heat, radiant heating, and the infrequent length of open periods.
Also, in cold months, the radiant floor heating keeps the interior comfortable, and opening a large door for a few minutes doesn’t severely degrade the conditions, especially since the building is well insulated and has some buffering.
What the blower door results tell us
The envelope passed the blower door test with the overhead doors in place. That is, the CFM50 was within acceptable limits for Phius certification. Actually, at 0.041 CMF/sq. ft. envelope area it came in well below the 0.06 Phius Standard.
The leakage measured around the doors was the biggest contributor, but not so large that it pushed the cumulative leakage out of spec.
Because Phius certification gauges leakage per envelope surface area a large-volume, large-surface-area building gives some “structural leverage” (i.e. some slack) compared to doing the same in a small house. Alan mentions that the difference is “generally more of a help in smaller buildings,” but that the spec approach worked in our favor at this scale.
The positive side (pressurization) behavior being tighter provides evidence that the door sealing is reasonably robust in practice (i.e. that when the doors are closed and pressed on, leakage shrinks).
Key Lessons & Recommendations for Others
If you’re designing or retrofitting a building with large overhead doors and want a high-performance, airtight envelope, here are the takeaways:
Don’t assume doors = failure
Large doors can be done—but only if you treat them as serious envelope components, not afterthoughts.
Specify insulated, high-quality doors
Choose doors with strong, insulated cores (e.g., polyurethane sandwich) and with good specified R-values. Be skeptical of manufacturer numbers—verify real-world performance if possible.
Upgrade the weatherstripping and make adjustability a priority
Expect to align, tweak, compress, and tune the seals in the field. Use premium sealing systems (vinyl, brushes, dual contacts, header/jamb seals) rather than the cheapest stock strips.
Attain extreme tightness in all other envelope assemblies
The less leakage in walls, ceiling, slab, and all junctions, the more budget you have for leakage through the doors.
Detail door-frame transitions carefully
The interface between the door frame and the building air barrier is a common leak path. Provide a continuous air barrier, good flashing, and appropriate sealants or gaskets there.
Test both directions
Do blower door tests in both pressurization and depressurization modes. Observing how leakage changes can hint at where sealing is weakest.
Expect real-use behavior mitigation
In real life, doors will open and close. But if the building is thermally resilient, and door operations are relatively infrequent or controlled (e.g. scheduled openings, secondary doors, etc.), transient losses are tolerable.
To learn more about our panelized Passive House approach — or to see the Instagram post that sparked this conversation — visit GOLogic.us or check out the original share from Ben Bogie / Fine Homebuilding here.