Concrete Sealing and Finishing
Sealing and finishing concrete is the difference between a slab that lasts 30+ years and one that scales, stains, and spalls within a decade. In Seattle's wet climate - 37–50 inches of rain annually, with moss and mildew common on unprotected surfaces - sealing is maintenance, not optional. Seattle Concrete provides finishing and sealing for driveways, patios, carports, garage floors, and interior commercial slabs across the Seattle metro area.
Sealer types: penetrating vs. topical
Penetrating sealers (silane, siloxane, siliconate) absorb into the concrete matrix and repel water and chlorides from within. They don't change the surface appearance or add gloss. They're the best choice for exterior driveways, walkways, and patios in Seattle's climate - they let the slab breathe while blocking moisture ingress. Reapply every 5–10 years.
Topical sealers (acrylic, epoxy, polyurethane) sit on the surface, adding a gloss or satin sheen and protecting against stains and abrasion. Acrylics are the most common for stamped and decorative concrete - they restore color and sheen, but require reapplication every 2–3 years. Epoxy and polyurethane are thicker and more durable, commonly used on garage floors and commercial surfaces. Requires proper surface prep to prevent peeling.
What surfaces to seal and when
New concrete should cure for at least 28 days before sealing. Existing slabs should be sealed when water stops beading on the surface - that's the visible indicator that the sealer has worn through. In Seattle's climate, exterior slabs typically need resealing every 2–3 years. Interior garage and commercial floors every 3–5 years. Stamped and stained surfaces need more frequent recoating (1–3 years) to maintain color and gloss.
Finishing services
Beyond sealing, we provide surface grinding to remove high spots and trip hazards, joint cutting and filling (polyurethane caulk for flexible joints, rigid epoxy for non-moving joints), and trowel finishing for new slabs to achieve the specified surface profile before any coating is applied. A proper finish and seal schedule saves money - a correctly maintained slab rarely needs early replacement.
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, most exterior concrete surfaces - driveways, patios, and walkways - should be resealed every 2–3 years. Interior garage floors and polished concrete may last 3–5 years between reseals depending on traffic. Watch for water no longer beading on the surface as a sign the sealer is wearing off.
Do I need a permit to seal concrete in Seattle?
Sealing existing concrete does not require a permit in Seattle. It is maintenance work with no structural component. If sealing is part of a new pour or a surface alteration that changes drainage, the underlying construction permit may cover surface treatment requirements.
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 existing coatings that may prevent adhesion. We pressure-wash, degrease, and allow the concrete to dry completely - at least 24 hours in Seattle's weather. Cracks and spalls are filled before sealing. Applying sealer over a damp or contaminated surface causes peeling and blush, so preparation is essential.
