Renton Rambler Addition
620 sqft single-story master suite + great-room addition on a 1971 rambler — Renton Highlands.
- Type
- Custom Addition
- Sqft
- 620
- Beds / Baths
- 1 / 1
- Completed
- Oct 2024
- Duration
- 24 wks
- Budget
- $218,000
01 / BRIEF
What the owner asked for
Owners wanted to age in place without stairs. Added a wheelchair-accessible master suite + great-room without compromising the original carport.
02 / CHALLENGE
What stood in the way
Existing rafters were 2x6 at 24" o.c. — insufficient to support a new flat-roof transition with PV panels. Required full structural rework of the existing roof tie-in.
03 / APPROACH
How we solved it
Sistered 2x10 rafters to existing 2x6s at the addition tie-in, then added a glulam ridge to support 5.4 kW of LG Neon PV.
04 / OUTCOME
What got delivered
Construction in 16 weeks after 8-week permit. Owners hosted Thanksgiving 2024 in the new great room.
SPEC_05 / FACTS
Project specification
- Footprint
- 620 sqft single-story
- Accessibility
- ADA-compliant turning radius, roll-in shower
SCHEDULE_06 / PHASES
24-week delivery
- 01Feasibility & design4–6 wks
Site survey, zoning memo, schematic plans, owner review.
- 02Construction docs3–4 wks
Structural, MEP, energy compliance, permit-ready set.
- 03Permit review8 wks
City corrections, utility sign-offs, building permit issued.
- 04Site work + foundation3–4 wks
Erosion control, excavation, footings, slab or stem wall.
- 05Framing + dry-in5–6 wks
Floor, walls, roof, windows, weather-resistive barrier.
- 06MEP rough-in + insulation4–5 wks
Plumbing, electrical, HVAC, blower-door prep.
- 07Finish + cabinetry6–8 wks
Drywall, paint, flooring, cabinets, tile, fixtures.
- 08Inspections + handover1–2 wks
Final inspections, punch-list, 16-week build closeout.
MATERIAL_07
Materials
- FloorEngineered white oak 7.5" plank
- RoofTPO single-ply with PV-ready penetration grid
SYSTEM_08
Systems
- Solar5.4 kW LG Neon R, Enphase IQ8M micros
- HeatingExisting forced air extended + radiant in bath
PERMIT_09 / RECORD
Permits & compliance
- Permit numberRenton B24-002188
METRIC_10 / OUTCOME
By the numbers
- 5.4 kW
- PV system
- ~6,100 kWh
- Annual PV offset
LESSON_11 / FIELD NOTES
What we'd repeat
- Always check existing rafter capacity before promising a flat-roof addition over a stick-framed rambler.
ARCHIVE_∞ / MORE
Other field reports
- REF_4492 · Detached ADUBallard Monolith
A 1,000 sqft two-story DADU clad in vertical western red cedar with floor-to-ceiling industrial glazing — long-term rental on a 4,800 sqft Ballard lot.
- REF_4376 · Attached ADUBellevue Wing
A 720 sqft side-yard AADU grafted onto a 1962 craftsman in West Bellevue — independent entry, separate utilities, no shared interior wall openings.
- REF_4218 · Garage ConversionKirkland Garage Studio
A two-car detached garage converted into a high-end work-from-home studio with a 6'x6' fixed skylight — Kirkland's Norkirk neighborhood.
Frequently asked
Can I tour a project like "Renton Rambler Addition"?
Yes — we typically have 6–10 ADUs in framing or finish at any time across the Puget Sound, so we can usually arrange a site walk on a project at the same stage you're planning. For completed projects, tours depend on the current owner's availability and privacy preferences. Request a tour and we'll match you to the closest active or completed project that resembles "Renton Rambler Addition" in size, configuration, and AHJ.
What did this project actually cost?
Each project page includes the all-in cost range for the size and configuration shown, scaled to 2026 prices. Actual contract value at time of build is confidential to the client, but the range we publish is anchored in real numbers from our bid archive — not aspirational pricing. For a tailored estimate against your lot, run our feasibility study or use the cost calculator.
Go deeper: Read the Five hidden ADU costs that wreck Puget Sound budgets guide
How long did this project take?
Most projects of this size and configuration run 9–14 months from contract to certificate of occupancy: 6–8 weeks of design, 8–16 weeks of permit, 18–26 weeks of construction. Schedule variance is driven by AHJ workload, owner selection pace, and field-discovered conditions during demo or excavation. We publish a Gantt at contract and update it weekly.
Go deeper: Read the Eastside deck cost & permits: cedar, IPE, composite (2026) guide
Could you build "Renton Rambler Addition" again on my lot?
Often yes — most of our projects are anchored on repeatable design DNA (envelope details, structural assemblies, MEP standard layouts) that adapt to different lot conditions with modest configuration changes. We'll review your lot's zoning, soils, and access to confirm fit. Where the original layout doesn't fit, we propose the closest workable adaptation that preserves the look you liked.
What inspections did "Renton Rambler Addition" go through?
Standard Puget Sound ADU inspection sequence applied: footing, underfloor MEP, framing, plumbing rough, electrical rough, mechanical rough, insulation, drywall nailing, shower pan, gas piping, final building, final plumbing, final electrical, final mechanical, and final energy verification (blower-door ≤3 ACH50). All passed with no notable callbacks — typical for our builds because we run internal QA checklists at each milestone.
INTERNAL_LINKS / Deep Map