Looking for home additions in San Mateo? ODL Construction is a licensed Bay Area general contractor serving San Mateo and the surrounding Peninsula — from San Mateo Park, Aragon, Hillsdale and beyond. Room additions, primary suites, and second stories that look original to the home.
In a market where moving up costs hundreds of thousands in transaction costs and a bigger mortgage, adding on is often the smarter play — especially in top-school neighborhoods where the right addition returns more than a relocation. The key is an addition that looks like it was always there, not bolted on.
For San Mateo specifically, it comes down to local realities: San Mateo's mix of period San Mateo Park homes and mid-century neighborhoods rewards remodels that match the era — generic finishes underperform here. San Mateo's building department is established and consistent; older neighborhoods can add character and tree considerations on exterior work. We design and permit your home additions around exactly those conditions.
Home Additions in San Mateo — what we handle
- Room and bedroom additions
- Primary-suite additions
- Second-story additions
- Bump-outs and rear extensions
- Structural engineering and foundation work
- Roofline and exterior matching
- Zoning, setback, and design-review compliance
- Permits and inspections
Home Additions cost
Typical Bay Area ranges, not a quote. Additions price by square footage, structural complexity, and foundation work. Second stories cost more because the floor below must be reinforced. You get a fixed proposal after design.
Timeline
Room additions typically run 3–5 months; second stories 5–9 months, including design, engineering, and permitting.
San Mateo permits
San Mateo's building department is established and consistent; older neighborhoods can add character and tree considerations on exterior work.


