Required tests + inspections at each stage

The inspections

SDCI inspects at multiple stages during the build:

• Foundation — before the pour.
• Framing — before insulation.
• Sheathing nailing — if shear panels.
• Electrical rough — by SDCI.
• Plumbing rough — by King County Public Health.
• Mechanical rough — by SDCI.
• Insulation — before drywall.
• Final — at substantial completion (drives Certificate of Occupancy in step 6.1).

Each inspection has to pass before the next stage starts. A failed inspection on Friday is a Monday-or-later re-inspection — and that delay cascades.

The required tests

For an addition, the Seattle Energy Code requires a blower-door test of the combined new + existing building:

• Blower-door test — measures air leakage at 50 Pa pressure. Limit on the combined building is more lenient than for new construction (typically ≤7 ACH50 instead of ≤5 ACH50, but verify with your designer against current code).
• Duct-leakage test — if the system has ducts. Limit: ≤4 CFM25 per 100 sf.

A specialist with calibrated equipment runs the tests, usually after drywall and air sealing but before final finishes. Costs:

• Blower-door: $300–$600.
• Duct leakage: $250–$450.

If the blower-door test fails, the GC finds and fixes the air leaks (often at the new-to-existing transitions), then retests. A failure that requires opening up walls is the worst case.

Why this is its own step

Inspections and tests punctuate the entire build, but they're not "a phase." They're the checkpoints between phases. Treating them as a single workflow step lets you track one clear deliverable (passing reports and sign-offs ready for CofO) without cluttering the build steps with inspection bookkeeping.