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There's no single best concrete sealer; the right one depends on the slab. Outdoors, use a breathable penetrating sealer: a siloxane for broom-finished driveways and walks, a silane for dense concrete that gets salted. On a smooth garage floor, use an oil repellent or a thin topical protector, and fix any crack before you seal.
What is the best concrete sealer?
The best concrete sealer is the one made for your slab’s finish and what attacks it. For most outdoor concrete that means a breathable penetrating sealer. For a smooth garage floor with oil drips, it means an oil repellent or a thin topical protector.
The NRMCA, the ready mixed concrete industry’s trade group, recommends a silane or siloxane based breathable concrete sealer (opens in a new tab) to protect slabs from freeze-thaw scaling. Iowa State University’s review of concrete sealers calls penetrating sealers an effective means of treating concrete pavements (opens in a new tab) and flags film-forming coatings for skid resistance and wear.
Use this finder to match the slab to the sealer:
| Your slab | Sealer | Type | Coverage (sq ft per gallon) | Guide |
|---|---|---|---|---|
| Broom-finished driveway, walk or patio | PS110 or PS102 | Siloxane or siliconate, penetrating | PS110: 150 to 200. PS102: 200 to 250 | Driveway sealer |
| Dense, smooth driveway that gets salted | PS109 | Silane, penetrating, solvent based | 200 to 350 | Driveway sealer |
| Smooth steps, porch, sidewalk or pool deck | PS101 | Siliconate, penetrating | 300 to 450 smooth troweled | Driveway sealer |
| Garage floor with oil drips, keep it looking bare | PS100 | Water, oil and salt repellent, penetrating | 300 to 450 smooth troweled | Garage floor sealer |
| Garage floor, want a thin film and stain hold-out | TS210 | Two-part polyurethane, topical | 800 to 1,000 smooth troweled | Garage floor sealer |
| Dusty garage or basement floor | PS104 | Lithium silicate densifier with repellent | 300 to 450 smooth troweled | Garage floor sealer |
| Foundation wall | None | Not for below grade waterproofing | Not applicable | Leaking crack guide |
PS100, PS101, PS104, PS109, PS110 and TS210 data sheets; PS102 product page
For most driveways and walks, the siloxane is the default pick. It’s water based, goes on milky white and dries clear, and its data sheet lists driveways and pool decks among its uses.
What does concrete sealer do?
A concrete sealer keeps water, and the salt and stains carried in it, from soaking into the slab. A penetrating sealer does it from inside the pores and lets water vapor out. A topical sealer does it with a film on the surface.
Keeping water out matters most where the slab freezes. The NRMCA explains that concrete saturated with water and exposed to freezing is susceptible to scaling (opens in a new tab), and that de-icing chemicals add to the saturation at the surface. A sealer cuts how much water gets in.
Here’s what a sealer won’t do:
- Fill or stop cracks. The PS-series data sheets say these sealers are not intended to seal cracks.
- Waterproof a basement wall. The same data sheets say they’re not for below grade waterproofing.
- Fix weak or damaged concrete. The data sheets say they won’t remediate structurally unsound surfaces.
- Work on asphalt. They’re made for concrete and masonry only.
Indoor slabs that stay dry often don’t need a sealer at all. The do you need to seal concrete guide covers when it helps and when it’s wasted money.
Penetrating or topical: which type do you need?
Penetrating for outdoor concrete, and either one on a smooth garage floor. A penetrating sealer soaks in, barely changes how the surface looks and keeps its traction. A topical sealer leaves a film that adds stain hold-out or sheen but wears and can get slick.
Iowa State’s review describes penetrating sealers as pore liners (opens in a new tab) that let gases and vapors pass through, while barrier coatings are too viscous to penetrate and sit on top. The sealer maker’s FAQ adds a one-way rule: a penetrating sealer can’t go over a topical one, though a topical can often go over a penetrating one.
The penetrating vs topical guide compares the two in detail.
How long does concrete sealer last?
Years, for a penetrating sealer, and less for a film. The sealer maker’s FAQ says penetrating water repellents can last up to 5 to 7 years or more, densifiers 10 years or more and topical acrylics about 1 to 3 years, with outdoor slabs at the low end of each range.
Research backs the long end for silane. Iowa State’s review cites a study that still found a protective effect from silane 20 years after it was applied (opens in a new tab), though the effect fades with sun, wear and weather.
To tell when it’s time to reseal, put a few drops of water on the slab. If they soak in within 3 to 5 minutes, the surface is taking water again. The driveway sealer guide covers how often to reseal a driveway.
When should you not seal concrete?
Don’t seal over cracks that haven’t been fixed, and don’t seal concrete that has moved. A sealer protects sound concrete. It does nothing for a slab or wall that’s shifting.
- Cracks wider than 1/4 inch, edges that sit higher on one side, or a slab that has sunk. Find the cause first. Start with the large cracks guide and the sinking slab guide.
- A basement wall crack that runs sideways, a bowing wall or a stair-step crack in a block wall. These need a structural engineer, not a sealer.
- Concrete under 28 days old. The sealer data sheets say concrete should be at least 28 days old or fully cured.
- A slab with an old topical coating. A penetrating sealer can’t soak through it; the coating has to come off first.
- A slab where water beads. If drops don’t soak in within 3 to 5 minutes, a penetrating sealer can’t get in either and may dry white.
Fill the cracks before you seal, because the slab kit’s data sheet warns that sealers stop its urethane from bonding. The sealing after crack repair guide covers the order and the wait.
How long does concrete sealer take to dry?
Most penetrating sealers dry to the touch in 1 to 3 hours and take foot traffic in 6 to 12 hours, per their data sheets. Cars wait longer: 24 hours after PS100 and 24 to 48 hours after PS109 or the TS210 topical.
Every sheet also sets a rain-free window after application: 12 hours for most of the PS series, 24 hours for PS100 and 48 hours for TS210. The sealer drying time guide has the full chart.
What goes wrong with concrete sealer?
The two common problems are a white or blotchy finish and a coating you want gone.
White haze usually comes from too much sealer or moisture. The data sheets warn that excess or over-application can leave a white residue, and say to brush out puddles so the sealer is absorbed within 10 minutes. The sealer turned white guide covers causes and fixes.
If an old topical coating is peeling or blocking a penetrating sealer, it has to be stripped or ground off. The sealer removal guide covers that.
Radon is a separate question from surface sealing. The radon and foundation cracks guide covers testing and what to do about cracks.
Every guide in this section
Is it a problem?
How to fix it
- Seal concrete after crack repair
- How long concrete sealer takes to dry
- Remove or strip concrete sealer
- Concrete sealer turned white
Products and comparisons
Questions
Does sealer fill cracks?
No. The penetrating sealer data sheets say the products are not intended to seal cracks, and the sealer maker's FAQ says to repair any crack wider than 1/16 inch before sealing. Fill the cracks first, then seal the whole slab.
Can I seal a basement wall to stop leaks?
Not with these sealers. The PS-series data sheets say they are not intended for below grade waterproofing. Water coming through a wall is a crack or drainage problem, and the leaking crack guide covers it.
Is a penetrating sealer safe on a pool deck?
Yes, it's the usual choice. PS110 and PS101 both list pool decks among their uses, and the PS101 data sheet lists minimal impact on traction.
Can I buy these sealers at a hardware store?
No. The maker's FAQ says its sealers are sold online, not in stores. Store brands of the same chemistry exist, so read the label for the type (silane, siloxane, siliconate or acrylic) and the temperature range.