Coastal vs Inland: How Long Stain Lasts

Every homeowner who stains a fence or a deck wants to know how long it will last. In San Diego County the honest answer is that it depends on which San Diego you live in. A finish on a fence a few streets from the sand in Imperial Beach and the same finish on a fence in El Cajon are dealing with different enemies, and they wear out in different ways.

What breaks a stain down inland?

Inland, the main enemy is ultraviolet light. Sunlight attacks lignin, the natural glue that holds wood fibers together, and once it breaks down the surface fibers loosen and turn gray. Pigment in a stain absorbs that light before it reaches the wood, but the pigment itself is gradually used up. Heat adds to it: a dark board in direct summer sun gets hot enough to dry the wood out and open small checks along the grain.

The inland pattern

In El Cajon, Santee, Spring Valley and La Mesa, wear follows the sun. The surfaces that go first are the ones that face it most directly:

• Deck boards and stair treads, which take sun from directly overhead for most of the day.
• Railing caps and the tops of fence rails, which are horizontal for the same reason.
• South- and west-facing fence boards and gates, which take the long afternoon sun.

The north side of the same fence, or a patio cover rafter in its own shade, may look nearly new at the same time. The color fades, the wood beneath grays, and if it is left too long the surface fibers become loose enough that they have to be cleaned or sanded off before a new coat will hold.

Santa Ana days add one more element. Hot, dry wind pulls moisture out of the wood and carries fine dust that settles into the grain and gets ground in underfoot.

What breaks a stain down on the coast?

Near the water (Imperial Beach, Ocean Beach, Point Loma, the bayfront), sunlight is softened by the marine layer for much of the year, so colors fade more slowly. The enemy instead is moisture that does not leave. Salt settles on every surface and holds damp against it, and the fog wets the wood again most mornings. Wood that is wet and dry, wet and dry, swells and shrinks with each cycle.

The coastal pattern

On the coast, wear follows the water:

• The bottoms of fence boards and posts, where wood is close to damp soil and dries last.
• End grain on rails, rafter tails and stair stringers, which drinks water far more readily than the face of a board.
• Shaded faces, where mildew grows on the surface of the stain and, in some oil-based finishes, feeds on the oils themselves.
• Around fasteners, where steel nails and screws rust in the salt air and stain the wood black or orange.

Coastal stain therefore often looks fine from a distance while it is failing at the edges. The surfaces that need checking are the ones people rarely look at.

The South Bay and the in-between

Much of the county lives between these two. Chula Vista, National City and Bonita see a genuine marine layer most mornings and real heat by the afternoon. Wood there gets both treatments in a single day: soaked by dew, then baked. That daily swing is hard on any finish, and it is why a product chosen only for sun or only for damp is rarely the right one for the South Bay.

Your own lot has its own climates

Even within one property, the differences are large. A few things that change the wear rate more than the address does:

1. Orientation. Inland, the south face of anything wears sooner than the north face. On the coast, the face toward the prevailing wind collects more salt.
2. Horizontal or vertical. A horizontal surface wears out well ahead of a vertical one in the same spot, because it takes sun from above and holds water on top.
3. Sprinklers. A fence that is soaked every morning by an irrigation head is living in a far wetter climate than the rest of the yard, wherever the house is.
4. Plants and soil against the wood. Shrubs pressed against a fence keep it from drying, and soil piled against the bottom boards wicks moisture straight in.
5. Shade from trees. It slows sun damage and speeds up mildew.

What stretches the time between coats

Some of this is in the homeowner’s hands. Turning sprinkler heads away from the wood, keeping soil and mulch off the bottom boards and trimming shrubs back so air can move are small changes that make a real difference. A gentle wash once or twice a year removes the dirt, pollen and salt that hold moisture and feed mildew.

The biggest single factor is when the recoat happens. A penetrating stain that is refreshed while it is still wearing evenly needs a clean and a coat. One that is left until the sunny boards are gray while the shaded ones still carry old finish wears unevenly, and usually needs stripping, brightening and drying first. The difference in work between those two jobs is large.

Pigment matters too. More opacity blocks more sun, which is why inland wood usually does best with semi-transparent or solid stain, while on the coast the breathability of the finish matters as much as the color.

Why there is no honest number

Product labels sometimes suggest how long a finish should last, but those figures assume conditions no San Diego yard reproduces exactly. Ebenezer does not promise a number he cannot stand behind. He looks at how your current finish is wearing, which faces are most exposed and what is soaking the wood, then tells you which parts will need attention first. He uses Dunn-Edwards and Sherwin-Williams stains, chosen for the exposure in front of him.

More on wood staining, and on what the salt does in Imperial Beach and the heat does in El Cajon.

If you would like to know where your fence, deck or patio cover is wearing worst and what would slow it down, ask for a free estimate. He will walk the wood with you, face by face, and give you a plan you can actually keep to.