Staining a deck or porch: which finish, how to prepare the wood and what it costs

Updated November 10, 2026 · KeystoneProGuide editorial team

Which finish should go on a deck?

It depends how often you want to do the job again. The USDA Forest Service's Forest Products Laboratory, in a release on deck care, describes three kinds of finish and how long each lasts:

The general rule it gives is that the more pigment a finish has, the longer it lasts and the more difficult it is to refinish. It adds that water-repellent preservatives contain a mildewcide or preservative to help control mold, mildew and algae. The laboratory's chemist says he refinishes his own deck with a water-repellent preservative every year or two, preferring a quick, frequent job to a heavier, rarer one.

How should the wood be cleaned first?

Gently. The laboratory says a deck must be cleaned before it is refinished, and its chemist warns against overly aggressive cleaners: some are strong enough to pulp the surface of the wood. His advice, as the release gives it:

• Use a commercial cleaner with sodium percarbonate as the active ingredient, or a 4:1 mix of water and household bleach with a little powdered laundry detergent. Use powdered detergent only, because liquid detergents, especially those with ammonia, can form noxious vapors with chlorine bleach.
• Laundry bleach tends to pulp the surface, particularly on cedar; lots of loose fibers washing off is the sign.
• Let the cleaner do the work. Aggressive scrubbing or a power sprayer can damage the surface in a way that later makes it hard for an absorbing finish to work.
• Spread the solution with a kitchen broom or sponge mop, keep it wet for about 15 minutes, treat no more than 200 square feet at a time, and rinse with a garden hose for at least 10 minutes.

How long should it dry, and when is the best time?

The chemist says to let the deck dry at least one day in the sun, that two to three days are probably better, and that you can wait two to three weeks before finishing. Working in Wisconsin, he names mid to late March as the time to clean, a cool, cloudy day as ideal, and April for the finish, since warmer weather helps penetrating finishes work. Treat those months as a sequence, not as Pennsylvania dates.

On semitransparent stain, the release warns of lap marks and suggests finishing the full length of two to four boards at a time.

What about painted porches and trim?

Paint behaves differently from stain. For bare or stripped wood that will be painted, Purdue Extension, writing with a Forest Products Laboratory scientist, recommends a paintable water-repellent preservative first, dried for at least two warm days, then a primer and at least one top coat. It says moisture is the most common cause of early paint failure on wood, so any leak or standing water that is wetting the boards needs fixing before the paint goes on.

What does deck staining cost?

HomeGuide prices staining a deck at $450 to $1,000 on average, or $1.50 to $4.00 per square foot, including power washing, staining and sealing. It puts painting a deck at $2 to $5 per square foot and stripping and repainting at $3 to $9. This is one national survey; no Pennsylvania figure is published.

Note that the survey's price includes power washing, while the Forest Products Laboratory's chemist cautions that a power sprayer can damage the wood surface. Ask how a contractor will clean the deck and at what pressure.

Is an old deck made of treated wood a concern?

Possibly, if it was built before 2004. The Environmental Protection Agency says wood treated with chromated arsenicals, including CCA, was used for decks and playsets until manufacturers stopped making it for homeowner uses in December 2003. The EPA does not require such decks to be removed, and says that applying a penetrating coating, such as an oil- or water-based stain, on a regular basis may reduce the leaching of chemicals. Its other cautions: wear goggles and a dust mask when sawing such wood, wash your hands after handling it, and never burn it at home.

And lead paint on an old porch?

Porches are on the Centers for Disease Control and Prevention's list of places where lead dust is common in pre-1978 homes. Scraping or sanding painted porch floors, rails or columns for pay is painting preparation under the EPA's lead rule once it disturbs more than 20 square feet outside, so a painter refinishing an old painted porch should be a certified firm working lead-safe.

Anything else to check?

Three small things. Wood preservatives are on the EPA's list of household sources of volatile organic compounds, so store leftover cans in a well-ventilated place out of children's reach, as the EPA advises for such products. In Philadelphia, the Historical Commission reviews painting, coating, staining or sealing of surfaces other than wood and metal trim on registered properties, so ask its staff before refinishing a porch on a listed house. And Delaware County's household hazardous waste events take leftover stains and varnish.

How often to repaint compares finish lifetimes with paint, and the cost guide covers house painting prices. Painters who stain decks are among those on the painters directory page.

Sources

1. Springtime Means Deck Maintenance for Many Homeowners, USDA Forest Service, Forest Products Laboratory
2. Paint Failure Problems and Their Cure (NCR-133), Purdue University Cooperative Extension Service
3. 2026 Deck Painting Cost, HomeGuide
4. Chromated Arsenicals (CCA), U.S. Environmental Protection Agency
5. About Lead in Paint, Centers for Disease Control and Prevention
6. Renovation, Repair and Painting Program: Contractors, U.S. Environmental Protection Agency
7. Volatile Organic Compounds' Impact on Indoor Air Quality, U.S. Environmental Protection Agency
8. Get approval for work to a historic property, City of Philadelphia
9. Household Hazardous Waste, Delaware County Solid Waste Authority