Figures below are planning ranges for Greater Los Angeles, intended to help you build a realistic budget. They are not a quote — every project is priced from its own site, scope, and selections.
Types of additions we build
Most additions fall into one of three shapes. The right one depends on your lot, your zoning, and how you want the house to live.
- Ground-floor room additions: a new bedroom suite, family room, or a larger kitchen built out into the yard
- Second-story additions: new space built on top of the existing house, which keeps your yard intact
- Bump-outs: smaller extensions that add a few feet where it matters most, like a kitchen or primary bath
What an addition costs
A permitted addition in Greater Los Angeles commonly costs $500 to $850 per square foot. That is often more per foot than building a new house, and it surprises people.
Three things drive it. You pay to connect old to new: matching rooflines, tying into the existing foundation, and blending finishes. You lose economies of scale, because each trade costs nearly the same to mobilize for 500 square feet as for 5,000. And the addition can trigger upgrades to the existing house, like a new electrical panel or a larger HVAC system.
Plan for 15 to 20 percent contingency. Older houses hide surprises behind the walls, and an addition opens those walls.
How long an addition takes
A single-room addition usually takes 4 to 7 months of construction. Design and permitting come first and often take as long again.
Plan check in Los Angeles typically takes 3 to 9 months, and longer on hillside or coastal lots. Each round of corrections usually adds four to eight weeks, so a complete first submittal is the best way to save time.
Second-story additions need an engineer first
Before anyone designs a second story, a structural engineer has to confirm the existing foundation and framing can carry it. Many older Los Angeles houses need foundation work, new shear walls, or new posts and beams to take the extra load.
A second story also changes how you live during the work. The roof comes off, so most families move out for at least part of construction. We plan that with you up front so there are no surprises.
Permits and zoning
Every addition needs a building permit. Zoning sets the limits: how close you can build to the property lines, how tall you can go, and how much floor area the lot allows.
Inside the City of Los Angeles, hillside lots may fall under the Baseline Hillside Ordinance, which generally limits floor area and grading more tightly than flat lots. Fire hazard zones and the Coastal Zone add their own requirements. We check these at the start so the design fits what the city will approve.
Frequently asked questions
How much does a room addition cost in Los Angeles?
A permitted room addition in Greater Los Angeles commonly costs $500 to $850 per square foot of new space. Hillside sites, structural upgrades to the existing house, and high-end finishes push toward the top of that range. Design, engineering, and permit fees are separate.
Is it cheaper to add a second story or build out?
Building out on the ground floor is usually less expensive, because a second story often needs foundation and framing upgrades and requires removing the roof. A second story makes sense when the lot has no room to expand or when keeping the yard matters more than the extra cost.
How long does a home addition take?
A single-room addition typically takes 4 to 7 months of construction. Add design and permitting beforehand, which in Los Angeles commonly takes 3 to 9 months for plan check alone.
Can I live in my house during an addition?
Often yes for a ground-floor addition, since most of the work happens outside the existing walls until the final tie-in. A second-story addition usually requires moving out for part of the job, because the roof is removed.
Do I need an architect for an addition?
You need permit-ready drawings and structural engineering. You can hire an architect directly and have us build from their plans, or work with us design-build, where we coordinate design and construction as one team.
