Assembly Review

Assemblies arrive already built up: on a consultant's section, in a manufacturer's detail, on a drawing from the last phase. The question is not whether the layers are reasonable. It is what this stack is trying to do, and which of those things it does not actually do.

Workflow

Step 1. Establish what it is and where it came from

Ask, in one message:

1. The layers in order, inside face to outside face, with any values given.
2. Where is this used, and what is on each side of it?
3. Who produced it: a consultant, a contractor, a manufacturer, a previous phase, a standard detail?
4. What climate zone, and from what source?
5. Is it presented as tested or listed, and is the listing cited?
6. What is being asked: is it acceptable, or what is wrong with it?

Question 3 changes what to look for. A manufacturer's detail is drawn to show their product working and the layers around it are decoration. A contractor's proposed alternate is drawn to be buildable and cheap. A previous phase's assembly is drawn to a brief that may have changed.

Read the order back, numbered, before anything else. An assembly given outside-in produces a clean reading that is exactly backwards.

Step 2. Say what the assembly is trying to do

Before finding faults, state the intent as the stack implies it. Then ask whether that matches what it has to do here. Half the findings in a review of an inherited assembly are not defects; they are an assembly built for a different job.

Step 3. Locate the four control layers

Control layer	Which layer is it	Continuous?	Where does it go at the edges

• Water. Which plane sheds bulk water, and does it drain or is it sealed?
• Air. Which plane stops air, is it continuous through the stack, and is it reachable to be sealed during construction?
• Vapor. Which is the lowest-perm layer, and which side of the insulation is it on?
• Thermal. Where is the insulation relative to the structure, and does anything cross it?

Where a layer cannot be identified, say so. An assembly with no identifiable air barrier is the most common finding and it is usually not deliberate.

Note where one material is doing two of these jobs, and say that one failure then takes out both.

Step 4. Find the layers doing nothing

Go through the stack and ask what each layer is for. Report:

• Layers with no job that anyone can name.
• Layers duplicating another layer's job.
• Layers whose job depends on a value nobody supplied.
• Anything present because it was on the last project.

This is where cost sits in an inherited assembly, and it is also where a layer turns out to be load-bearing for a reason nobody wrote down. Ask rather than delete.

Step 5. Say which way it dries, and what it cannot do

• Which direction can it dry, from where the low-perm layers sit? A direction, never a rate.
• Is it closed both ways, and if so is that deliberate?
• What does the assembly not address at all: thermal bridging at framing or penetrations, movement, fire, acoustics, buildability, maintenance.

State the last one plainly. A stack is a section through the middle of a wall and the middle of a wall is not where walls fail.

Step 6. Report

• What it appears to be for, and whether that matches the job here.
• The control layer table, with anything unidentifiable named first.
• Layers with no job, counted.
• The drying direction, and whether it is closed.
• Every value that came with the assembly and every one missing, counted.
• What this review did not cover, and the hand-offs: condensation-check for the arithmetic, air-barrier-trace for continuity around the building, the junction skills for the edges.

Step 7. Save, if asked

Ask whether to write the review to a file and where.

Rules

• Never supply a value. Missing is reported as missing.
• Read the layer order back before reviewing.
• Ask who produced it, and read it accordingly.
• State what the assembly is for before finding faults.
• Name any control layer that cannot be identified.
• Ask before calling a layer unnecessary.
• Say on every run that the middle of a wall is not where walls fail.

Anti-patterns

• Reviewing an assembly given outside-in as though it were inside-out.
• Treating a manufacturer's detail as a design.
• Listing faults without saying what the assembly was for.
• Assuming an R-value or a permeance to complete the picture.
• Deleting a layer nobody can explain rather than asking.
• Reporting a drying rate.
• Reviewing the section and never mentioning the edges.

Resources

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