- Typical cost
- $250 – $500+ per square foot depending on type and complexity
- Typical timeline
- 6–12 months including design and permitting
- Permits through
- Santa Monica Building & Safety
- Service area
- Santa Monica, Westside
Types of Additions
We build out, up, and into existing space, whichever makes sense for your lot, your budget, and what the city will approve.
- Single-story rear and side additions
- Second-story additions
- Primary suite and bathroom additions
- Kitchen expansions and bump-outs
- Enclosing patios and converting non-living space
Room Additions & Second Stories Conditions in Santa Monica
Salt air is the other factor. Openings, fasteners, flashing and exterior metal all corrode faster within a mile of the water, so we specify corrosion-resistant materials rather than whatever is cheapest on the shelf. Lots are narrow and street parking is limited, which means staging materials day by day instead of filling a driveway.
- 1920s to 1940s bungalows with galvanized pipe and original wiring
- Local energy and green building amendments above state minimums
- Corrosion-resistant windows, fasteners and flashing for coastal exposure
- Narrow lots with limited staging and parking for crews
- Foundation bolting and cripple wall bracing on most pre-war houses
What Drives the Cost
A second story usually costs more per square foot than building out, because the existing foundation and framing often need reinforcement to carry the new load. On a flat lot with room to spare, going out is almost always cheaper than going up.
- Foundation and framing reinforcement
- Roof tie-ins and re-roofing where they meet
- Panel upgrades and HVAC capacity
- Hillside and soils reports where applicable
Design, Engineering and Permits
Additions require structural engineering, Title 24 energy compliance, and full plan check. We coordinate the engineer, submit to LADBS or your city, and handle corrections until the permit is issued.
- Architectural plans and structural engineering
- Setback, FAR and height verification
- Title 24 energy calculations
- Plan check corrections handled by us
FREQUENTLY ASKED QUESTIONS
Do you do room additions & second stories in Santa Monica?
Yes. Santa Monica is part of our regular service area. We'll come out for a free on-site consultation, walk the property, and tell you what's realistic before you spend anything on design.
What does room additions cost in Santa Monica?
$250 – $500+ per square foot depending on type and complexity. Site conditions in Santa Monica and your material selections move the number, which is why we price after walking the property rather than over the phone.
Who issues the permit in Santa Monica?
Permits for this work go through Santa Monica Building & Safety. We handle the submittal, plan check corrections and inspections as part of the project.
How much does a room addition cost in Los Angeles?
Expect $250 to $500+ per square foot. Building out usually costs less than building up, and the finishes and any structural reinforcement the existing house needs move the number most.
Is it cheaper to build out or add a second story?
Building out is usually cheaper if your lot has room, because a second story often requires reinforcing the existing foundation and framing to carry the added load.
How long does a room addition take?
Plan on 6 to 12 months total: design and engineering, plan check at the city, then 3 to 6 months of construction depending on size.
Do you build home additions near me outside the City of Los Angeles?
Yes. We build primary suite additions, second stories and house extensions across a 100-mile radius of Woodland Hills, the San Fernando Valley, Ventura County, the Westside, the South Bay and Orange County. Each city runs its own plan check, and we handle whichever one governs your parcel.
Similar Projects We've Built
Second-Story Addition in Burbank
A 1,050 sq ft second story added over an existing 1940s single-story home, with foundation and framing reinforcement to carry the new load.
Family Room and Bath Addition in Glendale
A vaulted family room and full bathroom added off the rear of a 1958 Glendale home, opening to the backyard with a wide sliding door.
Room Addition on El Rodeo Rd, Rancho Palos Verdes
On El Rodeo Rd in Rancho Palos Verdes, a rear addition added a family room and fourth bedroom to a single-story peninsula home, matched to the existing roofline.
DISCUSS YOUR PROJECT WITH 1 SMART BUILD
Licensed, bonded and insured design-build general contractor serving Los Angeles County and Southern California. Tell us about your property and goals, and we'll walk you through feasibility, permitting and a clear plan.