Air Barrier Trace

Pick the air barrier up at one point on the section and walk it all the way around without lifting the pen. Everywhere you have to lift it is a joint, and that joint either has a detail or it does not. Water, vapor, and thermal ride along the same walk.

Workflow

Step 1. Establish the enclosure and the layer assignments

Ask, in one message:

1. Which drawings are we tracing? Sections, details, sheet numbers.
2. For each part of the enclosure, below grade, slab, wall, roof, glazing, which material carries the air layer? The water layer, the vapor layer, the thermal layer?
3. Where does the enclosure boundary run wherever the building steps, cantilevers, or meets an unconditioned space: garage, crawl space, unheated stair? That boundary is a decision, not a drawing convention, and the trace follows the one you name.
4. Is there an airtightness target? Quote it.

Say the assignments back before walking. A wall whose sheathing membrane is meant to carry both air and water, drawn lapped for water only, should fail at that sentence rather than thirty rows into a table.

Step 2. Walk the air layer, joint by joint

Fixed sequence. Every joint gets a row, including the ones that do not apply to this building, which are marked as such rather than dropped:

1. Footing and foundation wall to below-grade waterproofing
2. Foundation wall to slab edge
3. Slab or foundation to wall base
4. Wall to floor line at each level, including cantilevers and balconies
5. Wall to window and door rough openings: head, jamb, sill
6. Wall to wall at corners, and at every change of cladding or backup material
7. Wall to roof: parapet, eave, rake, and anywhere the wall passes the roof plane
8. Roof to roof at level changes and expansion joints
9. Penetrations: ducts, pipes, conduits, vents, structural steel, canopy and railing anchors
10. Every joint to an adjacent unconditioned space

If this building has something the list does not cover, an atrium, a tunnel, a vegetated roof, add the joint and say it was added.

Step 3. Repeat for water, vapor, and thermal

Same joints, one pass each. What to watch for, without supplying a number to any of it:

• Water. The joint has to shed downward and lap with gravity. A joint that is airtight and lapped upward is a hole.
• Vapor. Which side of the insulation the low-perm layer lands on, and whether it switches sides anywhere along the walk. The arithmetic belongs to condensation-check.
• Thermal. Where the insulation stops and what carries through the gap. Every one of those is a thermal bridge with a name and a location.

Step 4. Report

Joint	Layer	Inside material	Outside material	Connection	Drawing	Status

Status is one of four words. detailed, incomplete, not shown, conflict. Nothing else, and no fifth word invented for a joint that is nearly fine. A joint whose detail contradicts another detail is conflict and names both sheets.

Lead the summary with the count: how many joints are not shown and how many conflict, per layer. Not with the joints that are fine.

Then in prose: the joints where the layer changes material and plane at the same time, since that is where continuity usually fails; the ones whose detail exists on a sheet nobody would look at; and whatever could not be resolved from the drawings alone.

Step 5. Write it out

Ask where to write the table and the summary. If the project keeps an issue log or a checklist, offer to hand the not shown rows to drawing-checklist rather than tracking them twice.

Rules

• Never name a product. Not a membrane, not a tape, not a sealant, not in an example.
• A joint with no detail is not shown. Never "assumed continuous", never "typical", and "by others" only when a drawing note says so, in which case the row says who.
• Read the layer assignments back before walking.
• The air layer gets its own pass. Tracing four layers at one joint is how the air answer ends up borrowed from the water answer.
• Count what is missing on the face of the output.
• Never recall an airtightness rate, and never quote one found by web search.

Anti-patterns

• Marking a joint continuous because the assembly around it is conventional.
• Treating the water-resistive barrier and the air barrier as one line because one product often does both jobs. They are two requirements, they fail differently, and the lap and the seal are detailed separately.
• Designing the missing detail inside the report. Name what is missing; the detail is a design decision that goes through the normal review.
• Naming a tape or sealant that "always works there".
• Reporting a clean trace when half the joints came back not shown.
• Skipping the penetrations because they arrive as shop drawings. Most of them do, and those are exactly the ones nobody traced.

Resources

None. This skill is one file. Output is written directly at the path you choose.