Room Additions in the Seattle–Tacoma area
Sometimes one room changes everything: the bedroom that ends the sharing wars, the office that finally closes a door on work, the main-floor suite that lets a parent stay close. We design and build single-room additions that solve your specific space problem — beautifully, and to code.
The overview
Our approach to room addition
A room addition is the focused answer to a focused need. Rather than a sprawling project, we add precisely the space your household is missing — a bedroom, a home office, a bathroom, a mudroom, a sunroom — engineered onto your home so cleanly that guests will never guess where the original walls ended.
Focus does not mean simple. Even a single-room addition involves foundation work, framing tied into existing structure, roof integration, electrical and heating extensions, and full permitting. Our five generations of building experience make this scope routine, and our in-house 3D design team ensures the new room is placed and proportioned to improve the whole floor plan, not just append to it.
For families across Milton and the Seattle-Tacoma region weighing a move against staying put, a well-built room addition is often the most affordable path to the home that fits — and our fixed pricing and financing assistance keep the decision clear-eyed.
A note from Donovan
Your room addition, treated like it's our own home.
I'm Donovan. My family has been building across the South Sound for five generations, and every room addition project we take on gets the same promise: an honest budget range, a design you can walk through in photorealistic 3D before we build it, and a crew that treats your house the way we'd treat our own.
You won't be handed off to a call center or a stranger with a clipboard. You'll work with the same family that's earned its reputation one neighbor at a time — and we don't consider the job done until it feels like home.
— Donovan
Owner & Lead Designer · Licensed WA #HOMERDB750MH
Free design consultation
Tell us about your room addition project and Donovan's team will reply within one business day — no obligation, just honest advice.
Why choose us
What sets our room addition apart
Bedroom Additions
Code-compliant bedrooms with proper egress and closets — ending room-sharing, welcoming guests, and raising both livability and appraised value.
Home Office Additions
Purpose-built workspace with daylight, dedicated circuits, data wiring, and the acoustic separation a real workday requires.
Main-Floor Suites
Ground-level bedroom and bath additions designed for aging parents or aging in place — wide doorways, zero thresholds, and quiet dignity.
Bathroom & Mudroom Additions
The hardworking small spaces that transform household logistics, plumbed and built to last.
Sunrooms & Flex Space
Light-wrapped rooms for morning coffee, plants, play, or hobbies — insulated for genuine year-round use in our climate.
Placement Strategy
Our designers study your floor plan and lot to site the new room where it improves circulation and light for the rooms around it.
How it works
Our design-build process
Needs & Site Consultation
We define exactly what the new room must do and evaluate where your lot and structure best accommodate it.
Design & Rendering
Floor plan, exterior integration, and interior finishes are designed and shown in 3D for your approval.
Pricing & Permits
A fixed, itemized proposal is followed by engineering coordination and permit approval, handled entirely by our team.
Construction
Foundation, framing, roof tie-in, systems, and finishes proceed with your existing home protected and livable throughout.
Connection & Completion
We open the connection to your existing home, blend the finishes, and close out with inspection, walkthrough, and warranty.
When the tools come down and the crew heads home, what's left is yours — a house that finally feels like home.
Donovan& the crew
Start your room addition projectFAQs
Room Addition questions
How much does a room addition cost?
Most single-room additions in our area run $100,000 to $220,000 depending on size and whether plumbing is involved — bathrooms and suites cost more per foot than bedrooms or offices. You receive a fixed proposal from the approved design, with financing assistance available.
How long does a room addition take?
Design and permitting typically run six to ten weeks, with construction taking ten to sixteen weeks. Because the work is concentrated and mostly exterior until tie-in, disruption to daily life stays modest.
Where is the best place to add a room?
It depends on your lot's setbacks, your roofline, and what the new room should be near — bedrooms want quiet, offices want separation, suites want main-floor access. Placement strategy is the first thing our designers study.
Will one added room really change home value?
An added bedroom — especially with a bath — is among the most reliably valuable improvements in our market, often shifting your home into a different buyer category entirely. We design to appraisal standards so the value is bankable.
Do I need permits for a single-room addition?
Yes, always — any footprint expansion requires building permits and inspections. We manage the full approval process across Milton, Pierce County, King County, and neighboring jurisdictions as part of every project.
Can the addition be heated by my existing furnace?
Sometimes; it depends on your system's capacity and duct routing. Where extending ductwork is impractical, a ductless mini-split often serves the new room more efficiently — we evaluate both and recommend what is genuinely best.