Insulation, drywall, paint, and rough finishes

Sequence

1. Insulation — wall and ceiling insulation per WSEC 2021 CZ4C requirements, plus air-sealing details.
2. Drywall — hung, taped, mudded (3 coats), sanded.
3. Prime + first coat — walls and ceilings.
4. Trim carpentry — baseboards, casing, stair railings.
5. Paint — final coats.
6. Flooring — hardwood, tile, or LVT.

WSEC 2021 insulation targets (Climate Zone 4C — Marine)

Your energy compliance package from Phase 2 step 2.6 specifies the R-values required for your specific project, but the prescriptive minimums from WSEC 2021 Table R402.1.3 for the "Climate Zone 5 and Marine 4" column (which covers Renton) are:

Component	Minimum R-value or U-factor
Ceiling	R-60
Wood frame wall	R-20+5 or R-13+10 (cavity + continuous, choose one)
Floor	R-30
Below-grade wall	R-10/15/21 int + 5TB
Slab	R-10, 4 ft depth
Fenestration U-factor	0.30 maximum
Skylight U-factor	0.50 maximum

The wall option encodes a tradeoff: R-20 cavity + R-5 continuous or R-13 cavity + R-10 continuous. R-13+10 buys more thermal bridging protection at the cost of thicker exterior assemblies; R-20+5 is the more common framing target for new walls.

The air-tightness target under WSEC §R402.4.1.3.1 is 4.0 ACH50 (air changes per hour at 50 Pa) for detached one- and two-family dwellings — measured by a blower-door test before final inspection. For additions to existing pre-2009 homes the combined target is 7.0 ACH50.

The key air-sealing inspection (pre-cover inspection) happens before insulation goes in — the inspector verifies that penetrations, top plates, and rim joists are sealed per the energy drawings. Don't close walls before this inspection.

Why this phase comes before the kitchen

Kitchen install is sensitive to dust and to the underlying floor surface. Doing drywall, paint, and primary flooring first means the kitchen lands on a finished floor in a clean room. Skipping the sequencing produces visible joints, paint touch-ups behind cabinets, and floor seams in awkward places.