Home addition projects in the northwest metro typically range from $50,000 to $350,000 or more. Additions carry the highest dollar value per project of any service we offer, driven mostly by foundation type and whether you build out or up.
Cost by scope
Defined-Scope Addition
$50,000--$90,000
Single-room, ground-level addition (bedroom, office, family room) with minimal or no plumbing, a new foundation section, and an exterior tie-in to match the existing home.
Full Remodel Addition
$95,000--$160,000
Larger footprint or a room requiring plumbing, a full HVAC extension and electrical build-out, and a more complex roofline tie-in.
Premium Custom / Second-Story
$175,000--$350,000+
Full second-story addition or a primary suite over existing space, structural reinforcement, and complete roof removal and rebuild.
Most of the addition projects we complete are ground-level, single-room additions rather than full second stories.
What moves the budget most
Foundation type is the biggest factor. Compare a new ground-level foundation versus structural reinforcement for a second story. Ground-level vs. second-story is roughly double the per-square-foot cost. Plumbing or kitchen inclusion and roofline tie-in complexity round out the major drivers.
Where the money goes
- Labor
- 35--40%
- Foundation & structural
- 20--25%
- Exterior finishes
- 15%
- Interior finish
- 12--15%
- Permits & design
- 6--10%
Directional shares of a typical addition budget. Your project will vary.
Typical timeline
- Most home additions run 10 to 16 weeks depending on scope. A single-room, ground-level addition lands toward the shorter end; a second-story addition or one with plumbing extends toward the upper end.
Common questions
Answers before you call.
- Most fall between $50,000 and $350,000, depending on whether the addition is ground-level or second-story and whether it includes plumbing.
- Ground-level additions typically cost less per square foot, since they avoid the structural reinforcement, roof removal, and staircase framing a second story requires. Second-story additions preserve yard space.
- Most take 10 to 16 weeks. A single-room, ground-level addition lands toward the shorter end.
- Yes. Any addition that increases square footage requires building permits; second-story additions typically require a structural engineer's review as well.
- Use the DLI license lookup to confirm an active Residential Building Contractor license and that the legal business name matches your contract.
Next step
Talk through your addition with us.
Free in-home estimate. No pressure, no obligation. We will get back to you within one business day.
Request a Free Estimate