Sealing a concrete driveway, patio or garage floor protects it from water, freeze-thaw damage, oil stains and de-icing salts. Buying the right amount means reading the coverage on the label and accounting for coats and texture.
The calculation
sealer = area × coats ÷ coverage per coat × texture factor
Coverage depends on the product:
- Film-forming acrylic sealers often cover about 200 to 300 sq ft per gallon per coat. They give a sheen or “wet look”.
- Penetrating sealers (silane, siloxane, silicate) soak into the concrete and often cover 100 to 250 sq ft per gallon, depending on porosity. They leave the surface looking natural.
- Epoxy and polyurethane coatings for garage floors are thicker; see the dedicated garage floor calculator.
The texture factor accounts for rough surfaces, which drink more product: about 1.0 for smooth troweled concrete, 1.25 for a broom finish and 1.5 for stamped, exposed aggregate or very porous concrete.
For a 500 sq ft broom-finished driveway, two coats at 300 sq ft per gallon: 500 × 2 ÷ 300 × 1.25 = 4.2 gallons, so one 5-gallon pail.
Preparation
- Let new concrete cure, usually 28 days, before sealing, unless the product is a cure-and-seal.
- Clean thoroughly: degrease oil stains, pressure-wash and let the slab dry, often 24 hours or more.
- Repair cracks first.
- Check the weather: most sealers need temperatures above about 50 °F and no rain for 24 hours.
Application
Apply thin, even coats with a roller or low-pressure sprayer, working in sections and keeping a wet edge. Two thin coats are better than one thick one, which can stay cloudy or peel. Apply the second coat at right angles to the first, after the drying time on the label. Add an anti-skid additive to acrylic sealers on walkways and pool decks.
How often?
Acrylic sealers typically last 1 to 3 years on driveways; penetrating sealers often 5 to 10 years. Water that no longer beads on the surface is a sign it is time to reseal.