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Stained Concrete Floors in San Francisco, CA
A stained concrete floor is a bare slab colored from within by an acid stain or a dye and then protected by a sealer, and in San Francisco three things decide the job: the slab's own marks, the moisture rising through it, and the Bay Area's limits on what the stain and sealer may give off. The Bay Area Air District defines a stain as a coating made "to change the color of a surface but not conceal the grain pattern or texture." The ASCC Concrete Polishing Council's glossary calls an acid stain a "Reactive solution of one or more metal salts stabilized by acid that produces coloration in a concrete substrate" and a dye a colorant that "penetrates into the concrete while it is in solution."
Staining an existing slab: $3 to $15 a sq ft, national, HomeGuide (Feb 2026) · full pricing guide
No survey prints a San Francisco price for stained floors, so every figure here is national. HomeGuide's February 2026 staining page puts the average for an existing slab at $3 to $15 per square foot, lets acid-based stain reach $25, and tiers the work from "Simple, single color and sealant" at $3-$5 up to "Complex designs with stencils, scoring to mimic stone or tile" at $15-$25. Angi's July 2026 page spreads whole projects from $3,000 to $18,500 and lists "Concrete repairs: $800-$2,700" on its own line. Fixr (January 2025) quotes $2 to $25 a square foot indoors. The number of colors, scoring, the sealer and slab repairs move the total, and the published cost ranges put these rows side by side.
A specification names two products, the color and the sealer over it. The stain or dye works into the surface and the sealer meets the traffic; HomeGuide's staining survey says "Stained concrete should be sealed every 1 to 3 years," so the sealer is the part you renew. The Air District's rule defines a concrete/masonry sealer by its jobs: to "Prevent penetration of water," to resist "abrasion, alkalis, acids, mildew, staining, or ultraviolet light," or to "Harden or dustproof" aged concrete. The Concrete Polishing Council separates a film-forming coating, "greater than 0.05 mils," from semi-impregnating stain protection that leaves "a protective surface film of less than 0.5 mils." On a sealer's sheet, read the volume solids, how much of each wet coat survives as dry film: H&C's ClariShield wet-look sealer prints 29.9% and is "Not recommended for garage floors."
A stain colors only what it reaches, so preparation means opening the surface and finding what is on it. Sherwin-Williams' Form G-1 lists "oils, grease, wax, sealers, curing compounds" among what must come off before its resin floors, and the same residues stand between a dye and the concrete it should soak into. Sika's version of the water drop test, ASTM F3191, is the quick check: a drop absorbed within a minute marks the surface porous, one that sits longer marks it non-porous. When grinding opens a sealed or hard-troweled surface, the crew works under Title 8 section 1532.3, the Cal/OSHA silica rule, which gives walk-behind floor grinders a water feed or a dust collector with a filter of "99% or greater efficiency," and a HEPA vacuum between passes indoors.
The calendar is short and set mostly by the sealer. HomeGuide's staining page says the work "takes 1 to 3 days," and its November 2025 sealing page says "Most sealers take 12 to 48+ hours to dry before you can walk on it," though the sealer's own sheet has the final word. Outdoors, Prosoco says its Siloxane PD water repellent "gains its water-repellency properties in 72 hours," so rain matters: NOAA's 1991-2020 normals for the Downtown station put the days with 0.10 inch or more of precipitation at 8.0 in January and 0.0 in July, and the San Francisco floor data page sets out the station's normals. Clear the room first, tell the installer what was spilled or glued there, and keep rugs off until the sealer's cure time has passed.
A written quote for a stained floor depends on the slab, so expect a visit: the installer checks how the surface absorbs and looks for old sealer, adhesive and oil. Section 7159 of the Business and Professions Code covers home improvement contracts over $500 and asks for "a description of the significant materials to be used," which is where the stain, the sealer and its VOC figure belong. CSLB's C-33 painting and decorating definition lists "stains" among its materials and the D-6 subcategory of its C-61 class includes "coloring concrete," so look the contractor up on CSLB's site, class included; the hiring guide covers the down payment limit and the right to cancel. Any installer a request from this site reaches is independent and holds a California contractor license, and writes the quote and contract.
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Signs a slab will take a stain the way you want
A stain suits a slab you are content to see, in a room where the sealer can be renewed. Check these on the bare floor before a quote; a slab that fails one can still be stained, with more preparation, another sealer, or a cover.
- A drop of water darkens the bare concrete and soaks in within a minute, the porous result in Sika's account of ASTM F3191.
- You like the slab's own marks, since the Air District's definition says a stain changes color without concealing grain or texture.
- No white crust returns after the floor is washed and dried, since Euclid says a trace of calcium carbonate can shift the color.
- The cracks you can see are dormant, in ICRI's sense of not likely to move again, and you accept that they stay visible.
- The room takes foot traffic rather than hot tires, or you plan an epoxy or urethane sealer, which Euclid says marks less than acrylic.
- You can reseal on a cycle, and HomeGuide's staining survey puts that cycle at every 1 to 3 years.
A slab covered in patches or uneven repairs is a weaker candidate, because a stain will not even it out. A cement overlay gives a new surface, which Angi's national July 2026 resurfacing page prices at about $3 to $5 a square foot with "a basic, single-stain color"; the concrete resurfacing page covers the overlays.
What an acid stain or a dye does to an old San Francisco slab
An acid stain reacts with the slab and a dye soaks into it, so in both cases the concrete is part of the recipe. In the Concrete Polishing Council's definitions, an acid stain "produces coloration in a concrete substrate" and a dye is "applied and penetrates into the concrete." San Francisco's slabs bring their history to that reaction. The Showplace Square context statement hosted by SF Planning describes "Later concrete 'daylight'-frame structures" from the First World War era and the 1920s building boom, and the General Plan says the area's warehouses were renovated "to provide furniture showroom space." SF Planning's Sunset statement places integrated garages in that district's houses of the 1920s to 1950s. Old slabs like these carry patches, saw cuts and spills, and a stain shows each one.
Moisture matters too: Sherwin-Williams' Form G-1 says "Excess moisture in concrete can produce harmful effects of discoloration," and Stonhard warns that slabs "over 25 years old" may have no moisture barrier, so a moisture test belongs in the prep, above all before a film-forming sealer. The safeguard for all of it is a test area on your own slab, sealed the way the full floor will be, before the color is chosen. The Dogpatch and Potrero Hill page covers the warehouse district's buildings and ground.
The Bay Area limits for stains and concrete sealers, row by row
In the Bay Area a stain may carry up to 250 grams of VOC per liter and a concrete or masonry sealer up to 100, under the July 1, 2009 text of the Air District's Regulation 8, Rule 3. VOC means volatile organic compounds, the vapors a product gives off as it dries and cures, counted "in grams of VOC per liter of coating." The rule's Table 2, which "shall be effective on and after January 1, 2011," prints "Stains 250" as one row, not split into interior and exterior, beside "Concrete/Masonry Sealers 100," "Primers, Sealers, and Undercoaters 100" and "Reactive Penetrating Sealer 350"; an opaque floor coating is held to 100. Where a product is recommended for more than one category, section 8-3-302.2 applies "the most restrictive limit," with listed exceptions, and the Air District's 2011 advisory says "All coatings manufactured after these dates must meet the VOC limits below to be sold in the District." CALGreen, the State's green building code, prints the same marks in its 2025 Table 4.504.3, "Stains: 250" and "Concrete/masonry sealers: 100," which apply "unless more stringent local limits apply." CARB's April 2019 staff report proposed taking exterior and dual-use stains from 250 to 100 while leaving interior stains at 250, a proposal rather than a Bay Area rule.
What shows through a stain: salts, cracks, tires and patio water
A stain hides nothing, so whatever is in or under the slab stays part of the floor. Efflorescence, the white bloom of salts, can shift the color on its own: Euclid Chemical says it "occurs when water migrating through concrete or masonry picks up free salts and other soluble materials and deposits them on the surface," and that "Only 0.2 ounces of calcium carbonate per square yard of surface is needed to cause a significant shift in color." Euclid ties the secondary kind to water "after rain, from irrigation, or the surrounding soils" and adds "Diverting moisture away from the slab helps as well." Craze cracks, the fine map-pattern cracks NRMCA calls "more noticeable on steel-troweled surfaces," do not affect structural integrity, in NRMCA's words, but a stain does not fill them.
ICRI calls a crack dormant when it is "not likely to become active in the future"; ask which kind each crack is before it is filled or left. Tires leave their own marks: Euclid traces hot-tire pickup to "plasticizer migration" and says "Most discoloration from plasticizer migration occurs on acrylic or styrene/acrylic cure & seals," while epoxy and urethane sealers "are much more crosslinked." On a patio, Prosoco says its Siloxane PD "Will not keep water out of cracks, defects or open joints," so ask how the open joints and cracks will be treated.
Which sealer goes over the color, or polish instead
Once the color is chosen, the sealer is the real decision: is the slab damp, will tires touch it, and how often will you reseal? Three options trade protection against breathability and upkeep in the makers' and surveys' figures; the fourth skips the film and polishes the stained surface.
Acrylic sealer, renewed often
An acrylic film is the low-cost choice: Angi's national July 2026 page prices "Acrylic sealer: $0.85-$1.15 per sq. ft." over a stain. HomeGuide's November 2025 sealing page says "Acrylic sealers last 1 to 3 years on average," and Euclid says acrylic cure-and-seals show the most tire marking. It suits an indoor room with foot traffic and an owner who will reseal on schedule.
Epoxy or urethane sealer film
A crosslinked film resists tires better, in Euclid's account, and HomeGuide's sealing page says "Epoxy or urethane sealers last 5 to 15 years." Angi's July 2026 national list puts epoxy sealer at $3-$7 per square foot, polyurethane at $0.95-$1.10. The catch is moisture: Sika says vapor trapped "beneath an impermeable film" can "blow sections off or cause other forms of damage like blisters." It suits a dry slab that passed a moisture test, garages included.
Breathable penetrating sealer
A silane or siloxane sealer soaks in instead of building a film. In Prosoco's words, treated surfaces "'breathe' - does not trap moisture"; its Siloxane PD sheet lists "150-200 sq.ft." a gallon and "Not recommended for below-grade application." HomeGuide's national November 2025 page prices penetrating sealers at $1.00 to $3.00 per square foot installed. It suits patios and slabs where a breathable concrete sealer is specified.
Stain, then polish
Polishing grinds and hones the stained surface instead of covering it. Fixr's national January 2025 page prices polishing at up to $30 per square foot when the floor is first stained "in a pattern or in layers," and Prosoco says its lithium densifier "will improve the resistance of concrete surfaces to staining" though acids can still etch. It suits a sound slab that can take grinding; the polished concrete page covers gloss levels and care.
Stained Concrete Floors FAQs
How much does it cost to stain a concrete floor in San Francisco?
No survey publishes a San Francisco price, so the guide is national data. HomeGuide's staining page (February 2026) prints 200 square feet at $600 to $3,000, 500 square feet at $1,500 to $7,500, and a stained two-car garage from $2,000 to $14,400; sealing the stain adds $1 to $3 per square foot. Angi (July 2026) spreads whole projects from $3,000 to $18,500. The number for your slab comes after a site visit, in the installer's written quote.
What is the difference between an acid stain and a concrete dye?
An acid stain reacts with the concrete, while a dye soaks in as a colored solution. The Concrete Polishing Council calls an acid stain a "Reactive solution of one or more metal salts stabilized by acid" and says a dye "results in a stained appearance." HomeGuide's national February 2026 survey prices water-based stain from $3 to $15 a square foot installed and acid-based stain from $3 to $25. Either way, ask for a test patch on your own slab before choosing.
Will stained concrete hide cracks and patches?
No. A stain changes color and keeps texture, so cracks, patches and saw cuts stay in view; the Air District's definition says a stain does "not conceal the grain pattern or texture." Craze cracks, which NRMCA says are "rarely more than 1/8 inch" deep, remain as fine lines, and ICRI separates dormant cracks from active ones that are "still moving." Where the surface is too patched to stain well, an overlay can give a uniform base first.
How do you take care of a stained concrete floor?
Care is mostly care of the sealer, which HomeGuide says to renew every 1 to 3 years. Over an epoxy or urethane sealer, resin makers' advice applies: Stonhard recommends "mild, pH-neutral cleaners and soft tools," and Laticrete says walk-off mats "will help increase the life of the floor." Prosoco warns that "acid concentrates and acidic foods may etch" even a densified floor, so wipe spills fast. On a stained and polished floor, avoid cleaners "that are highly alkaline or acidic," as a Concrete International article advises.
Can you stain an outdoor concrete patio in San Francisco?
Yes, with a sealer and schedule chosen for weather. Euclid suggests a penetrating silane or siloxane sealer "for sealing exterior concrete where tire marking is or may be a problem," and Prosoco's Siloxane PD needs 72 hours to reach its water repellency. Euclid ties secondary efflorescence to water "after rain, from irrigation, or the surrounding soils." The Air District's rule text of July 1, 2009 gives exterior and interior stains one limit, 250 grams of VOC per liter.
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