Sealed concrete guide: sealers, timing, and upkeep

Last updated: October 27, 2026

Sealed concrete keeps water, salt, oil, and stains out of a slab that drinks more than it looks like it would. A bare slab can soak up 4 to 6 percent of its own weight in water. That number comes from the ASTM C642 absorption test, not a brochure. So wait about 28 days to seal a new pour, put down two thin coats, and reseal when water stops beading.

Water sitting in the pores is what freezes, swells, and pops the top off in flakes. That’s called scaling. It can show up on a driveway or a set of front steps after as few as 20 to 50 freeze-thaw cycles. That’s a couple of bad winters, not a couple of decades.

A sealer’s job is to manage those pores. It comes with two side effects, and both belong in your choice, not in the fine print. Most sealers change the color and sheen a little. And every sealer changes how the slab handles a freeze and thaw. Pick the type whose side effects you want.

Penetrating or topical sealer

A penetrating sealer soaks in and reacts with the concrete. Silane and siloxane water repellents line the pores, so water beads up and runs off instead of soaking in. Silicate and lithium densifiers harden the slab from the inside. Either way you get little or no film. The slab keeps breathing, and the grip underfoot barely changes. That makes it the default outside, and on any slab that sits through freeze and thaw.

A topical sealer sits on top as a film. Acrylics are the low-cost choice for decorative work. They’re cheap, easy to recoat, and good at making color pop. Epoxies and polyurethanes are tougher and glossier. They all share one risk. Put a film over a damp slab, or one that needs to breathe, and vapor pushes up under it until the film peels. When our check of a slab shows a warning sign, an ASTM F1869 test reads how much moisture it gives off. Most film sealers fail above 3 lbs per 1,000 SF in 24 hours.

Seal, polish, or coat: pick by thickness

Sealing is the thinnest thing you can do to a slab. It protects the concrete without changing what it is. It costs the least, takes the least time, and the floor still looks like concrete when we’re done.

Polishing isn’t a product at all. Diamond tools grind and refine the top until it’s dense and glossy, with no film to peel. On a showroom floor or a busy indoor floor, that usually beats a topical sealer outright. The polished concrete guide walks through how it works.

A coating is the thick end. Epoxy or polyurethane builds a real film, measured in mils, or thousandths of an inch. It’s what you want when chemicals or forklifts are part of the day. It costs the most, and it asks the most of the prep.

Pick by where the slab is and what it takes:

• Driveway, patio, or walk: a penetrating sealer. A film is a liability outside, and letting the slab breathe matters most.
• Indoor floor you want hard and shiny: polish it.
• Chemicals, forklifts, or heavy wear: a coating.
• Stamped or stained color you want to pop: a topical sealer, with grip mixed in if it gets wet.

What about stamped, stained, and decorative concrete?

On decorative work, the sealer’s main job is guarding the color. Color is the weakest part of the surface, whether it came from pigment mixed into the concrete, acid stain, or dye. Left bare, it fades, dusts off, and washes out. A sealer stops all three, and the sealer is the part you refresh over the years, not the stain. It also wets the color and brings out a depth you can’t get any other way. A stained slab under sealer and the same slab bare barely look related.

Stamped patios usually get an acrylic topcoat 1 to 2 mils thick, refreshed every 1 to 3 years. It often has an anti-slip additive mixed in, because a wet stamped surface with a film on it is slick. Exposed aggregate, the finish with the stones showing, gets a reseal every 3 to 5 years. The stamped concrete guide covers topcoats on stamped work. The decorative concrete guide covers acid-stained and dyed floors.

How do you put a sealer down correctly?

Wait about 28 days to seal new concrete, so the slab has time to cure. Seal it early and you trap curing water under a film. A few weeks later it comes back as peeling or a cloudy white blush. There’s one exception. Cure-and-seal compounds made under ASTM C309 are built to go on a green slab, meaning one that’s still fresh. That’s a different product doing a different job than a topcoat sealer a month later. Mixing up the two is how green slabs end up with the wrong film on them.

Prep is most of the job. The slab has to be clean, dry, and free of any old sealer that’s failing. Before a topical sealer, we check for dampness when there’s a warning sign: no vapor barrier under the slab, a recent pour, a basement floor, or damp spots. Tape a plastic sheet down on all four edges overnight, per ASTM D4263, or run a calcium chloride or relative humidity test. If the slab is holding water, no product on the market solves that. The film just becomes the lid.

How many coats of sealer? Two thin ones beat one thick one, every time. A heavy coat can’t let its solvent or water out fast enough, so it skins over on top while the sealer under it stays soft. That’s where bubbling, haze, and peeling come from. Two light coats each cure all the way through and lock into the layer below. On a film sealer, we wait 2 to 4 hours between coats.

Then stay off it for a bit. On a floor we seal, you can walk on it lightly after 4 to 8 hours and park on it after 24 to 48 hours.

Last, grip. Any film sealer turns slick when it’s wet. A walkway, a pool deck, or a ramp needs anti-slip grit spread into the sealer or mixed in before it goes down. Penetrating sealers rarely have this problem, which is one more reason they own the outdoors.

When is it time to reseal?

The first sign is water. When it stops beading and starts soaking in, darkening the concrete where it lands, the repellent is used up. The second sign is color: a flat, chalky, thirsty look with the richness washed out of it.

How often you seal concrete depends on the sealer type and what the slab sees. A penetrating sealer outside often lasts several years, because it lives inside the pores where traffic can’t scrub it off. A topical sealer may want a fresh coat every 1 to 3 years in busy spots, and sooner where tires or a snow shovel work on it. De-icing salt runs its own clock. ASTM C672 measures how well a slab holds up to scaling under salt, and that drops off as soon as the sealer quits shedding water.

You don’t need a calendar reminder. Pour a cup of water on the slab in spring. If it beads, you’re fine for another year.

What does sealing concrete cost, and what drives its lifespan?

Our sealed concrete runs $1.31 to $3.42 a square foot, plus the drive cost, which is our trip to your site. Prep moves that number more than the sealer does. A clean, sound slab is cheap to seal. A slab with old failing sealer, oil stains, or efflorescence (the white salt crust) has to be stripped or ground first. That line usually runs bigger than the sealer line on the bid.

After prep, two things move the price. One is the type you buy, a penetrating water repellent or a high-build topical system. The other is what rides along with it, like an anti-slip additive or color enhancer. The quote tool prices your slab with the options you pick.

Lifespan is mostly about exposure, and the spread is wide. A shaded walkway with a penetrating repellent might go 7 to 10 years untouched. A south-facing driveway under road salt and full sun can wear through a topical film in 1 to 2 years. That’s the same product and the same crew on two very different clocks, and neither one is a defect.

For an indoor floor, price a harder finish before you sign up for a reseal you’ll repeat for twenty years. Compare sealing to a mechanical polish. It’s worth ten minutes, because a polished floor inside lasts longer with less upkeep. For outdoor slabs and decorative surfaces, sealing on a set schedule is the right answer. Our sealing service covers the check, the clean, and the recoat.

Seal it late and you’ve already lost surface you can’t get back. Seal it right and you won’t think about it again until the water stops beading.