TL;DR
Concrete stains because it is porous, and a sealer works by filling or covering those pores. Sealing typically buys three to five years of easier cleaning and better stain resistance, then has to be redone. Cleaning alone costs less per event but never gets easier. The break-even usually favors sealing on a driveway that sees vehicles and favors cleaning on a rarely used slab.
Why concrete restains so quickly
Cured concrete is not a solid sheet. It carries a network of capillary pores left by the water that was in the mix, and those pores wick liquid inward the way a paper towel does. That is why a drop of motor oil disappears into the surface instead of beading on it.
Once a stain is below the surface, cleaning it becomes a chemistry problem rather than a scrubbing problem. Surface soil rinses off. Absorbed oil has to be drawn back out with a degreaser or a poultice, and it rarely comes out completely. How to remove oil stains from concrete walks through what actually works.
Porosity also explains the seasonal green film. Damp, porous concrete in shade holds moisture, and moisture grows algae. Clean it in spring and it is back by fall.
What does a concrete sealer actually do?
A sealer either penetrates the pore structure and lines it, or forms a film on the surface. Either way it reduces how fast liquid soaks in, which turns most spills into something you can wipe up instead of something you have to extract. It does not make concrete stainproof and it does not stop cracking.
The two families of sealer
Penetrating sealers (silanes, siloxanes, silicates) soak in and react below the surface. They leave the look of the concrete almost unchanged, they do not peel, and they resist water and salt intrusion well. They are less effective against oil than a film, and they add no gloss.
Film-forming sealers (acrylics, epoxies, urethanes) build a layer on top. They deliver strong stain resistance, deepen the color, and can be glossy. They also scuff, they can peel if applied over damp or dirty concrete, and they can be slippery when wet unless a grit additive is used.
For an unheated exterior slab in a wet climate, a penetrating sealer is usually the more forgiving choice. A film that traps moisture in a slab with no vapor barrier underneath will eventually blush white or delaminate.
What sealing requires that people underestimate
The prep is the job. A sealer applied to dirty concrete permanently locks that dirt in place, and a sealer applied to damp concrete may never bond.
Clean thoroughly first, including degreasing every oil spot. How to clean a concrete driveway covers the sequence.
Let it dry. Manufacturers commonly ask for 24 to 48 hours of dry weather before application, and longer after pressure washing, because the slab holds water you cannot see.
Check for existing sealer. Sprinkle water on the surface. If it beads, something is already there, and a different chemistry over it can fail. If it soaks in within a minute, the slab is open.
Watch the temperature and the forecast. Most products want a surface between about 50 and 90 degrees F, out of direct sun, with no rain for 24 hours or more.
Respect the cure. Foot traffic usually returns in a day, vehicle traffic often in three days or more. Parking on a green film ruins it.
New concrete has its own rule: most manufacturers ask you to wait roughly 28 days before sealing so the slab can cure and release moisture.
What it costs to go each way
Industry Baseline Range
| Scope | Industry baseline range |
|---|---|
| Pressure washing a house | $170 to $360 |
| Pressure washing a deck or driveway | $100 to $260 |
Source: HomeGuide, "Pressure Washing Prices" national cost guide.
These are industry baseline ranges for planning only and may not reflect Otesse's price. Otesse pricing is calculated for your specific home and ZIP code, so enter your ZIP in the price box on this page for your instant price.
Current Market Reality
Exterior service pricing has moved well above older published baselines. Labor is the largest line on any wash or seal job and wage costs have climbed steadily. Sealer chemistry is petroleum-linked, so material prices track fuel. Insurance and equipment costs on ladder and pressure work have risen faster than general inflation, and in wet regions the short dry-weather window compresses the season, which pushes scheduling premiums into spring and late summer.
Site conditions move a quote more than any list can. Slope, access for a truck, the age and porosity of the slab, existing coatings that need removal, and the amount of oil present all change the number. Treat these ranges as a way to sanity-check a bid, not as a price.
How the approaches compare with one another:
| Approach | Relative cost (lower to higher) | Interval |
|---|---|---|
| DIY cleaning supplies per session | Lowest | Yearly or more often |
| Degreasing and stain treatment, per event | Lower | As needed |
| DIY sealer materials, average two-car driveway | Lower | Every 3 to 5 years |
| Professional pressure washing, driveway | Middle | Yearly or more often |
| Professional concrete sealing | Higher, per square foot | Every 3 to 5 years |
Every job is different, so the real number depends on the details above. Enter your ZIP in the price box on this page to see your instant price.
How the decision usually breaks
Seal it if vehicles park on it, if it is decorative or stamped concrete you care about visually, if it sits in freeze-thaw conditions where de-icing salt gets tracked on, or if you are tired of degreasing the same two spots every spring.
Skip the sealer if the slab is a utility pad nobody looks at, if it already has an unknown coating you are not prepared to strip, if it stays damp because of a drainage problem you have not fixed, or if it is cracked and spalling badly enough that resurfacing is the real answer.
The same reasoning applies to interlocking pavers with one extra step, because their joints are structural. Sealing pavers versus resanding the joints is a separate decision from sealing the paver faces.
What sealing will not fix
It will not stop cracks. Concrete cracks from shrinkage, settlement, and freeze-thaw, and a surface coating has no structural role.
It will not cure efflorescence. That white bloom is salt carried to the surface by moisture moving through the slab, and sealing over it can trap the moisture and make the problem worse. What efflorescence is explains why the moisture source has to be addressed first.
It will not eliminate cleaning. A sealed slab still needs sweeping, rinsing, and an occasional wash. It just makes each of those faster and keeps the results longer.
For a whole-property view of which outdoor surface needs what, see the exterior surface cleaning guide.
The honest verdict
On a working driveway, sealing usually wins over a five-year horizon. The material cost is modest, the labor is a weekend, and it converts recurring hard cleaning into occasional easy cleaning.
On a slab that never gets stained and never gets looked at, sealing is money spent on a problem you do not have. Rinse it in spring and move on.
Whichever you choose, do the cleaning either way. A sealer is a decision to protect a clean slab, not a way to avoid cleaning a dirty one.
FAQ
Is sealing a concrete driveway worth it?
Usually yes if vehicles park on it. Sealing reduces how deeply oil, salt, and water penetrate, so routine cleaning gets easier and stains stop becoming permanent. It typically lasts three to five years and then needs reapplying, so it is a maintenance commitment rather than a one-time fix.
How often does concrete need to be resealed?
Most residential sealers are rated for roughly three to five years, shorter on a driveway with heavy vehicle traffic and longer on a covered patio. The water-drop test tells you when: if water soaks in instead of beading, the sealer is spent.
Can I seal concrete that still has oil stains?
No. A sealer applied over an oil stain locks it in permanently, and the coating may not bond to the contaminated area at all. Degrease the spots, rinse thoroughly, let the slab dry fully, and only then apply.
Does sealing concrete stop cracks?
No. Cracking comes from shrinkage, settlement, and freeze-thaw movement inside the slab, and a surface coating has no structural effect on any of that. Sealing reduces water and salt intrusion, which can slow related deterioration, but it does not prevent cracks.
How long after pressure washing can I seal concrete?
Longer than the surface looks. Most manufacturers ask for at least 24 to 48 hours of dry weather after washing, and more in humid or cool conditions, because concrete holds water below the visible surface. Sealing over trapped moisture causes clouding and peeling.
What happens if I never seal my concrete?
Nothing dramatic. Unsealed concrete performs fine structurally; it simply absorbs more, stains more readily, and needs cleaning more often. In freeze-thaw regions with regular salt exposure, surface scaling is more likely over the long run on an unsealed slab.
Will a sealer make the surface slippery?
A film-forming sealer can, especially a glossy one when wet. Penetrating sealers change traction very little. If you want a film on steps or a walkway, use a product with a grit additive or choose a matte formulation.
Protecting a surface is cheaper than restoring it, outdoors and indoors both. If the inside of the house is what has gotten away from you, our house cleaning crews are local and background-checked, with upfront pricing and no hidden fees. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.
