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Building enclosure control layers · Lesson 4 of 4

Building enclosure control layers: defects, verification and case study

Six defects the four-layer trace catches at a parapet, how a mock-up, field observations, inspection and a whole-building test verify the layers, and a constructed case that fails its test and its own drawings.

You will be able to: Recognize six common control-layer defects at a parapet, say how mock-ups, field QA and whole-building tests verify the layers and who performs them, and walk a constructed case from test result to evidence packet.

11 min · 12 slides · 8 questions

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Slide 1 of 12

Defect 1: the air line stops at the deck

Defect 1: the air line stops at the roof deck. BSC's problem parapet has no air control in either the roof or the wall assembly.

BSC says such a parapet shows air leakage into and out of everything and everywhere.

Continuity at the parapet, incorrect and correctTwo schematic parapet sections side by side. Left, incorrect: the air line has a visible break at the roof deck, stopping short of the wall layer, the water line does not reach the top of the parapet so there is no membrane under the coping, the coping top is flat, and the insulation band stops at the roof-to-parapet corner. Right, correct: the water, air, vapor and insulation lines run unbroken from the roof, up the parapet, under a coping that slopes toward the roof and down the outside face. Four numbered points mark the same four places in each. A key names the line styles: solid blue water, dashed green air, dotted teal vapor, hatched amber insulation, red metal coping.Continuity at the parapet12341234IncorrectCorrectWaterAirVaporInsulationMetal copingSchematic, not to scale. The design teamdetails the fix at each numbered point.

Two schematic parapet sections. Incorrect: the air line has a visible break at the deck, there is no membrane under the coping, the coping top is flat and the insulation stops at the corner. Correct: all lines run unbroken under a coping that slopes toward the roof. Four numbered points mark the same places in each.

1
The air line: broken at the roof deck on the left, continuous on the right
2
The water line: no membrane under the coping on the left, a membrane under it on the right
3
The coping top: flat on the left, sloped toward the roof on the right
4
The insulation: stops short of the parapet on the left, continues up and over on the right
Schematic, not to scale. The key names the line styles. The design team details the fix at each numbered point; the incorrect panel is a teaching drawing, not a project.

Sources

Glossary

Mock-up
A built sample of the enclosure and its transitions, approved before the work starts where one is required. UFGS 07 27 10 includes the floor-wall, wall-window and wall-roof connections.
Diagnostic evaluation
The 2021 IECC step for a whole-building result over 0.40 but not over 0.60 cfm/ft2: smoke tracer or infrared imaging while the building is pressurized, a visual inspection, sealing of leaks and a report to the code official and owner.
Final commissioning report
Under the 2021 IECC, the report on air barrier inspections that identifies deficiencies found and the corrective measures taken, given to the owner and the code official.
Air Barrier Auditor
The Air Barrier Association of America certification that UFGS 07 27 10 names, or documented equivalent experience, for its air barrier inspector.