Concrete Sealing and Finishing in Seattle
Concrete sealing is the protective coat applied to cured concrete, and concrete finishing is the surface texture created while a new slab is still workable. Both decide how long a slab lasts in Seattle, where 37–50 inches of rain a year, shaded lots and moss wear down unprotected concrete far faster than in drier regions. Seattle Concrete provides sealing and finishing for driveways, patios, walkways, steps, garage floors and interior commercial slabs across the Seattle metro area.
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Which sealer for which surface
There is no single "best" concrete sealer. The right product depends on whether the surface is a driveway, a decorative patio or a garage floor, and on whether you want the concrete to look natural or glossy. This table sums up the usual Seattle choices:
| Surface | Usual sealer | Why | Typical reseal |
|---|---|---|---|
| Broom-finish driveway | Penetrating silane or siloxane | No surface film to peel or turn slick; blocks water and de-icing salts | 3–5 years |
| Patio, walkway, steps | Penetrating; acrylic only if you want a wet look | Keeps walking surfaces as grippy as bare concrete | 3–5 years (penetrating) |
| Stamped or stained concrete | Acrylic, with a slip-resistant additive | Brings back color depth and sheen | 1–2 years |
| Exposed aggregate | Penetrating, or a low-gloss acrylic | Acrylic deepens stone color but adds slipperiness | 1–2 years (acrylic) |
| Garage floor | Epoxy or polyurethane coating system | Resists oil, hot tires and road salt | 5–10 years (epoxy) |
| Interior commercial slab | Epoxy, polyurethane, or densifier for polished floors | Abrasion and chemical resistance | Depends on traffic |
For product-by-product detail, see our comparison of penetrating, acrylic, epoxy and polyurethane sealers.
Penetrating vs. topical sealers
Penetrating sealers (silane, siloxane, siliconate) soak into the concrete and form a water-repellent layer inside the pores. The surface looks and feels like plain concrete, water beads and runs off, and there is no film to wear through or peel. They are the default for exterior driveways, walkways and patios in the Pacific Northwest because they let the slab breathe while keeping rain and chlorides out.
Topical sealers (acrylic, epoxy, polyurethane) form a film on top of the slab. Acrylics are the standard on stamped and stained concrete because they restore color and sheen, but they wear faster outdoors and are slippery when wet unless a grit additive is used. Epoxy and polyurethane are thicker, harder coatings used on garage floors and commercial interiors. Every topical sealer depends on surface prep: applied over a damp, dirty or previously coated slab, it peels or turns cloudy (called "blushing").
A Pacific Northwest reseal schedule
Seattle's weather sets the calendar for sealing. The slab has to be dry, and most sealers need surface temperatures of roughly 50–90°F while they are applied and cure, so late spring through early fall is the working season. A practical schedule looks like this:
- New concrete: wait at least 28 days after the pour before sealing, or longer if the product label says so.
- Every year, in fall: clear leaves and needles, look for moss in joints and shaded corners, and do a water test on high-traffic areas.
- Every 1–2 years: recoat acrylic on stamped, stained and decorative surfaces.
- Every 3–5 years: reapply penetrating sealer on driveways, patios, walkways and steps.
- Before any reseal: wash, remove growth and stains, fill cracks, and give the slab at least a full dry day, with no rain forecast during the product's cure window.
The easiest check is the water test: sprinkle water on the slab. If it beads, the sealer is still working. If the concrete darkens and soaks it up within a minute or so, it is due. Our guide on how often concrete needs sealing and the signs it's time covers the warning signs in more detail.
Moss, algae and rain
North-facing slabs, paths under trees and patios next to fences can stay damp from October through April. Moss and algae root in the surface pores and control joints, hold water against the concrete, and make walking surfaces slick. A sealer helps because it cuts down how much water the slab absorbs, so the surface dries faster after each rain. It does not kill growth that is already there.
The order matters: remove the moss and algae first, rinse, let the slab dry completely, then seal. Sealing over live growth traps it under the coating. Aggressive pressure washing can etch the surface and expose sand, which gives new growth more to grip, so moderate pressure and a wide fan tip are safer. Trimming back branches, fixing downspouts that discharge onto the slab and keeping joints clear do as much as the sealer itself. Our guide to removing moss and mildew from Seattle concrete walks through safe cleaning methods.
Slip-resistant additives
Film-forming sealers smooth out the concrete's texture, and a wet acrylic or epoxy surface can be noticeably slicker than bare concrete. On any walking surface that gets rained on (steps, ramps, entries, pool decks, sloped driveways), a slip-resistant additive belongs in the final coat. The common options are fine polymer grit mixed into the sealer or a mineral grit, such as aluminum oxide, broadcast into the wet coat. More grit means more traction but a surface that is harder to clean, so the amount is matched to how steep and how wet the area gets. Penetrating sealers don't change surface texture, which is one reason they are preferred on broom-finished walks and driveways.
Concrete finishing types
The finish is decided at the pour, and it determines how the slab handles water, traction and wear for its whole life:
- Broom finish: a stiff broom is dragged across the fresh slab to leave fine ridges. It's the standard for driveways, walkways and sidewalks because it grips when wet and costs the least. The ridges run across the direction of travel or slope.
- Trowel finish: steel trowels, by hand or with a power trowel, leave a smooth, dense surface. It suits garage floors, basements and interior slabs that will get a coating or polish, but it is too slick for most exterior walking surfaces.
- Exposed aggregate: the top layer of cement paste is removed to reveal the stones in the mix. The texture hides wear and stays grippy on shaded garden paths, and a sealer helps lock the stones in place.
- Stamped and colored finishes: patterns and color are added while the concrete is plastic. See decorative concrete for stamped, stained and colored options.
Finishing work on existing slabs includes cutting and filling joints (flexible polyurethane sealant for moving joints, rigid epoxy for joints that don't move) and grinding high spots and trip hazards before a new coating goes down. If a slab is cracked, scaling or spalled beyond what a sealer can protect, it needs concrete repair first.
Sealing as part of routine maintenance
Sealing works best as one step in a yearly routine: sweep and wash, deal with stains while they are fresh, keep water draining off and away from the slab, fill small cracks before winter, and reseal on schedule. Our guide to year-round concrete maintenance in Seattle lays out that routine, and freeze-thaw protection explains why a sealed slab handles cold snaps better.
Frequently asked questions
How much does concrete sealing cost in Seattle?
Concrete sealing in Seattle typically costs $0.50–$2.50 per square foot for a standard topical sealer and $1–$4/sq ft for a penetrating or decorative sealer. Driveways, patios, and garage floors are priced by area. Larger flat surfaces cost less per square foot than intricate stamped or stained surfaces. Get a free on-site estimate for an accurate quote.
How often should I seal concrete in Seattle?
In Seattle's wet climate, plan on reapplying a penetrating sealer on driveways, patios, walkways and steps every 3–5 years, and recoating acrylic on stamped or stained concrete every 1–2 years. Epoxy garage floor coatings can last 5–10 years depending on traffic. When water stops beading and the concrete darkens as it soaks water up, the sealer has worn off.
Do I need a permit to seal concrete in Seattle?
Sealing an existing slab is surface maintenance with no structural work, and SDCI's guidance lists patios and concrete slabs on grade among projects that usually don't need a permit. If sealing is part of a larger project, such as a new pour, regrading, or sidewalk work in the public right-of-way, that project's permit rules apply.
What is the difference between penetrating and topical concrete sealers?
Penetrating sealers (silane, siloxane, or siliconate) absorb into the concrete and protect from the inside without changing the surface appearance. They are ideal for driveways and exterior slabs in Seattle's rainy climate. Topical sealers (acrylic, epoxy, polyurethane) sit on the surface, add gloss, and protect against stains, but can peel if the surface is not properly prepared.
How should I prepare concrete before sealing?
The surface must be clean, dry, and free of old coatings that would block adhesion. Typical prep is pressure washing, degreasing oil spots, removing moss, and filling cracks and spalls, then letting the concrete dry completely, at least 24 hours of dry weather in Seattle. Sealer applied over a damp or contaminated surface peels or turns cloudy.
Will sealing stop moss from growing on my concrete?
Sealing slows moss and algae down but doesn't prevent them on its own. A sealed slab absorbs less water and dries faster, which makes it harder for growth to take hold. Shade, standing water and debris in the joints still matter, so remove existing growth before sealing and keep the surface clear and draining.
Does sealed concrete get slippery?
Penetrating sealers leave the surface texture unchanged, so they don't add slipperiness. Film-forming sealers such as acrylic and epoxy can be slick when wet, so walking surfaces outdoors should get a slip-resistant grit additive in the final coat, especially on steps, ramps, entries and pool decks.
Which concrete finish is best for a Seattle driveway or walkway?
A broom finish is the usual choice for driveways, walkways and sidewalks because it gives good traction in the rain at the lowest cost. Exposed aggregate is a good option for shaded paths where algae is a concern. Smooth trowel finishes are best kept to garages and interior floors.
Service areas
We handle concrete sealing and finishing across King, Snohomish, Pierce, and Thurston counties, including in Bonney Lake, Orting, Eatonville, and Enumclaw. See all service areas.
