Deck Painting & staining right here in Billerica, Massachusetts.

A deck takes weather on its flat face. Snow sits on it for days, rain pools in checks and at board ends, and sun hits the whole surface at once, so a deck finish wears far faster than the paint on the wall beside it. For that reason, cleaning and repair take up much of a deck job, not just the coat itself.

Detached single-family houses are 73.3% of local housing units, and for those the owner decides product and color alone. Townhouse-style attached homes, 5.8% of units, are another matter: decks may be lined up side by side, and condominium documents can treat them as limited common areas with set colors or association maintenance.

Water, shade and the boards nearest the ground

The Concord and Shawsheen rivers both run through town, and Nuttings Lake has a public beach used for canoeing and sailing (see the Nutting Lake neighborhood page). Census figures put water at about 1.9% of the town's area. Whether or not a house is near water, anywhere a deck is low to the ground, under trees, or on the north side of a house, boards dry slowly and grow mildew and algae. Those decks need a thorough cleaning and a mildewcide-containing product, and they are where rot shows first.

Check the boards at the house ledger, stair stringers, and the bottom step. If a screwdriver sinks into them, they get replaced before any coating, since stain does not hold wood together.

Matching the finish to the wood

The paint vs. stain comparison sets out how each wears, and how deck stain holds up through a New England winter explains why horizontal boards fail before rails.

• New pressure-treated lumber: wait until a sprinkle of water soaks in rather than beading, then apply a penetrating or semi-transparent stain
• Weathered pressure-treated: clean and brighten, then a semi-transparent or solid stain depending on how worn and checked the boards are
• Cedar or mahogany: oil-based or semi-transparent stains show the grain; a tannin-blocking primer is needed under light solid colors
• Composite or PVC: cleaning, not coating, unless the manufacturer approves a specific product
• Boards already under paint or solid stain: stay with a film-forming finish unless the deck is stripped to bare wood

Porches on older houses

One in ten local housing units (10.2%) was built in 1939 or earlier, and where a house that age has an open front porch with a painted floor, balusters and columns, those parts get scraped, primed and repainted in porch-and-floor enamel, not stained. Surfaces that old may carry lead paint, and scraping falls under the EPA's lead-safe rule once more than 20 square feet of exterior paint is disturbed in paid work on a pre-1978 house; see the lead-safe painting page.

If the porch belongs to a house in one of the four local historic districts, rebuilding rails or posts in a new design or material can require Historic Districts Commission review, even though repainting a residence in the same color is treated as maintenance under the posted by-law.

Timing and the order of work

Stain needs dry wood, mild temperatures and a clear forecast through its cure window; it should go on in shade or early in the day so it soaks in instead of skinning over. If the house itself is due for paint, do the siding and trim first so drips land on boards about to be cleaned, then finish the deck last. The Billerica exterior painting page covers the house side.