Deck Painting & staining across Concord, Massachusetts.

A deck finish fails faster than house paint because the boards lie flat. Snow sits on them, water pools along the joints and fasteners, and the top face takes direct sun all summer. The finish you choose now sets the maintenance for years, so decide between a penetrating stain and a film-forming one before the first coat, not after the second one starts peeling.

Single-family detached houses account for 68.6% of local housing units. The 4.8% of units that are single-family attached and the 18.5% in buildings of five or more units are where association rules on deck color and materials are more likely to come into play, so owners there should check their documents before choosing a stain.

Know what lumber you have

Manufacturers stopped making CCA-treated wood for homeowner uses in December 2003. EPA does not call for removing existing CCA decks, and it notes that regularly applying a penetrating oil- or water-based stain may reduce the chemicals leaching out. That makes staining an older deck a maintenance step, not just a cosmetic one.

• Newer pressure-treated pine: has to dry out before staining; if a splash of water soaks in rather than beading, it is ready
• Pressure-treated lumber from before 2004: may be CCA-treated; wear a dust mask and goggles when cutting it and never burn scraps
• Western red cedar and redwood: suited to oil-based and semi-transparent stains that let the grain show
• Composite and PVC boards: typically cleaned rather than coated, unless the manufacturer approves a product
• Boards with old solid stain or paint: can only take another film-forming coat unless stripped back to bare wood

Stain or paint: the long-term trade-off

Penetrating stains soak into the wood and wear away gradually, so each recoat is a cleaning and a fresh application. Solid stains and porch enamels sit on the surface, block more UV and hide mismatched boards, but when they fail they peel, and the peeling has to be scraped before the next coat. The paint vs. stain comparison goes into more detail, and how deck stain holds up through a New England winter explains why horizontal surfaces wear first.

Porches on district and antique houses

A painted tongue-and-groove porch floor on a house from the 22.6% of local housing built in 1939 or earlier can have lead in its lower layers. EPA's lead-safe rules apply to paid exterior work in pre-1978 housing that disturbs more than 20 square feet of paint, a mark that scraping a porch floor and its steps can pass. The lead-safe painting page covers what that involves.

In the six local historic districts, exterior changes visible from a public way need review, and the town counts the Concord, Assabet and Sudbury Rivers as public ways, so a rear deck facing the water is not hidden from the rules. The guidelines name walls, trim, doors, shutters and fences for color review; whether a deck or porch color change is treated the same way is a question to put to the Planning Division before buying stain. Ordinary maintenance and repair needs no hearing, but the guidelines exclude replacement and any change in color, material, design or size from that exemption, so swapping out rotted porch boards is also worth raising with the Planning Division.

Prep and timing

A deck coating can fail because of what lies underneath: mildew, gray loose fibers, or an old finish never removed. The sequence is a deck cleaner, a thorough rinse, a brightener to restore the wood after cleaning, sanding of raised fibers, and full drying time. Popped nails get reset, and soft boards, stair treads and post bases are replaced before any stain goes on.

Stain needs dry boards and a stretch of dry weather for curing, so the season runs from late spring into early fall. If the house is being painted the same year, doing the deck last keeps drips and ladder feet off the new finish; the exterior painting page covers the house side.