Looking for a basement waterproofing contractor in San Mateo, CA? Describe your project once and up to three waterproofing contractors who work in San Mateo and San Mateo County get back to you with a quote. It's free and there is no obligation.
San Mateo is home to about 103,006 people (2024 Census Bureau estimate), a shrinking community (−2.5% since 2020). With 8,489 people per sq mi, it is a densely built-up area. Heavy rains, high water tables and older foundations are the usual causes of wet basements here.
San Mateo at a glance
- Population (Census Bureau estimate, 2024)
- 103,006 (−2.5% since 2020)
- Rank in California
- 71st of 482 cities and towns
- Land area
- 12 sq mi
- Population density
- 8,489 people per sq mi (densely built-up)
- Type
- City (San Mateo city)
- Main county
- San Mateo County
What to check before hiring in San Mateo
- Outside first: check gutters, downspouts and grading before paying for a system.
- License and permit: in California, check the contractor's license and whether a permit is needed.
- Warranty: ask what it covers, whether it is transferable and who backs it.
- Price drivers: wall length, system type, sump pumps and excavation.
Useful official resources
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EPA: mold
Official information and guidance.
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ICC: International Code Council
Official information and guidance.
Services available in San Mateo
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Interior drain tile and sump pump
Interior perimeter drain, sump pump and vapor barrier to keep water out of the basement.
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Exterior waterproofing
Excavation, membrane and footing drain on the outside of foundation walls.
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Basement crack sealing
Injection or sealing of leaking cracks in poured or block foundation walls.
Frequently asked questions in San Mateo
How much does basement waterproofing cost in San Mateo, CA?
It depends on the system and the size of the basement. Describe the problem: contractors who serve San Mateo reply with a quote.
How long does it take?
Interior systems often take a few days; exterior work takes longer.
Will waterproofing stop mold?
It removes the main cause. Existing mold should be cleaned up separately.
Which waterproofing contractors will contact me?
Up to three independent waterproofing contractors who serve San Mateo 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.