Looking for an addition contractor in Half Moon Bay, CA? Describe your project once and up to three addition contractors who work in Half Moon Bay and San Mateo County get back to you with a quote. It's free and there is no obligation.
Half Moon Bay is home to about 11,324 people (2024 Census Bureau estimate), a shrinking community (−4.0% since 2020). With 1,814 people per sq mi, it is a suburban area. Growing families here often add space instead of moving.
Half Moon Bay at a glance
- Population (Census Bureau estimate, 2024)
- 11,324 (−4.0% since 2020)
- Rank in California
- 357th of 482 cities and towns
- Land area
- 6.2 sq mi
- Population density
- 1,814 people per sq mi (suburban)
- Type
- City (Half Moon Bay city)
- Main county
- San Mateo County
What to check before hiring in Half Moon Bay
- Zoning: check Half Moon Bay's setbacks, lot coverage and height limits first.
- License and permit: in California, additions are built by licensed contractors under a permit.
- Structure: second stories need an engineer to check the existing house.
- Price drivers: size, foundation, roof tie-in, plumbing and finishes.
Useful official resources
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ICC: International Code Council
Official information and guidance.
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NAHB
Official information and guidance.
Services available in Half Moon Bay
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Room addition
Ground-floor addition with foundation, framing, roof and finishes.
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Second-story addition
New floor over the existing house, with structural engineering.
Frequently asked questions in Half Moon Bay
How much does an addition cost in Half Moon Bay, CA?
It depends on size, foundation and finishes. Describe your project: contractors who serve Half Moon Bay reply with a quote.
How long does it take?
Often a few months, plus design and permits.
Does an addition raise property taxes?
Usually, since it increases the assessed value.
Which addition contractors will contact me?
Up to three independent addition contractors who serve Half Moon Bay and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.