📍
Westlake
Thousands of Doelger split-levels on 25-to-30-foot lots. Remarkably uniform: same era (1945–1965), same developer, same basic floor plan.
PACIFICA-BASED CONTRACTOR — CSLB #1041528
Home Additions in Daly City — Expanding a Home That Was Built for a Different Era
Doelger split-level homes built for post-war affordability now need room to grow. We know the foundation, the framing, and the half-level geometry.
Why Local Expertise Matters
Split-Level Homes Need Strategic Expansion
Henry Doelger built Daly City’s Westlake homes to be affordable. His split-level design was efficient — three bedrooms, one or two bathrooms, typically 1,100 to 1,400 square feet, with a single-car garage tucked below the living level. He built thousands of them between 1945 and 1965, and the formula worked.
Seventy years later, those homes sell for $1.1 to $1.3 million and the families living in them need more space than Doelger planned for. A primary suite. A real family room. A home office. A fourth bedroom for the child who moved back. The homes are well-built and well-located — close to BART, minutes from San Francisco — but they were designed compact.
Adding to a Doelger split-level is a specific kind of construction challenge. The split-level geometry — half-levels connected by short staircases, living space above and garage below, bedrooms up another half-flight — makes every home addition decision more complicated than the same decision on a standard single-story ranch.
📍
Based In Pacifica
188 Clarendon Rd. — serving Daly City and the Peninsula since 2018
Neighborhoods
Where We Build in Daly City
- 📍Serramonte
1960s and 1970s homes on larger lots and wider streets than Westlake. Many are single-story ranch homes rather than split-levels.
- 📍St. Francis Heights
Post-war tract homes on inclined streets with bay views. A mix of split-levels and single-story homes on terrain requiring site-specific drainage design.
- 📍Broadmoor
Unincorporated community with older housing stock — 1920s–1940s homes on larger lots. Bungalows and ranches, not split-levels.
- 📍Original Daly City
Northern neighborhoods adjacent to the San Francisco border. Older, smaller homes on smaller lots. Mixed housing stock, constrained opportunity.
- 📍Colma
South Daly City with newer post-war construction. Larger lots and more design flexibility for additions.
- 📍Not Sure?
Every lot is different. Call (650) 224-3052 and describe your property. We'll tell you what's feasible in your neighborhood.
Investment
What Room Additions Cost in Daly City
Daly City room addition costs are lower than San Francisco (simpler permitting, better access) but higher than typical Peninsula suburbs due to split-level structural complexity.
*All ranges reflect Peninsula market conditions — varies by scope, site conditions, and finish level
Rear Addition on Split-Level
200–400 sf — family room, expanded kitchen, or primary suite
$105K – $165K+Second Story on Split-Level
600 sf — includes foundation reinforcement, shear wall installation
$240K – $390K+Second Story on Ranch
600 sf — simpler load path than split-level
$225K – $360K+Lower-Level Conversion
150 sf — utility/storage to living space
$30K – $60K+Primary Suite Addition
350–450 sf rear addition at main living level
$175K – $325K+
All ranges include design, structural engineering, permitting, and construction. The largest variables are site conditions and existing structure complexity. We provide detailed cost estimates after the structural assessment.
Our Process
How We Build Room Additions in Daly City
Structural Assessment
We evaluate your home's foundation, framing, existing systems, and lot constraints. This is where we identify what's feasible and what the existing structure needs before construction.
Design
Plans that reflect your home's structural realities and your local zoning requirements. Design-build means our team stays integrated from concept to completion.
Permitting
We submit plans to the local planning and building departments and manage the entire review process. We file regularly in Daly City and know the approval timeline.
Construction
Our crew handles all structural work — foundation reinforcement, framing, connections. We build it right the first time, with inspection at each stage.
Completion
nterior finishes, exterior integration so the addition looks like it was always part of the home, final inspections, and certificate of occupancy.
Why ACI
Why Daly City Homeowners Choose ACI
Based on the Peninsula
We're at 188 Clarendon Road in Pacifica, serving Pacifica and neighboring communities. We know the local building departments, the soils, the housing stock, and the permitting timelines.
We Do Structural Work
Foundation reinforcement, framing, shear walls, seismic connections — our crew handles this directly. No coordination gaps with separate engineers and contractors.
Engineering First
We bring the structural engineer in before design starts. Plans reflect your home's structural realities from day one — no surprises during construction.
Design-Build Model
One contract, one team for design, engineering, permitting, and construction. Eliminates coordination gaps and keeps your project on track.
CSLB #1041528
Licensed GC — Class B
Bonded & Insured
Family-Owned