In Whatcom County, well-installed and properly maintained cedar siding typically lasts twenty to forty years, with painted or well-finished cedar landing at the higher end and neglected or bare cedar falling well short of that. The number is not really about the wood itself so much as how it is finished, fastened, and allowed to dry between rain events, which in this part of Washington happen often.
Cedar is naturally resistant to decay because of the oils in its heartwood, and that is a real advantage over many other siding woods. But natural rot resistance is not the same as rot immunity, and it does not do much for you if water is sitting against the wood for days at a time, which is a normal condition here between October and April. Homeowners who see cedar failing at twelve or fifteen years almost always have one or more of the same problems: no back-priming, tight or caulked joints that trap water instead of letting it drain, or a finish that was never renewed.
The single biggest factor is the finish, not the grade of cedar. A clear or semi-transparent stain lets the wood breathe and is easy to maintain but needs attention every three to five years in this climate. Solid-body stain and paint film last longer between coats, but eventually trap moisture if the substrate underneath was not properly dried and sealed first, and once paint starts failing on cedar it tends to fail badly, with peeling that exposes bare wood to standing water.
Back-priming — coating the back and edges of each board before installation — matters more here than in drier climates, because the back of the board is the side that stays wet longest against the wall. Grain orientation matters too: vertical-grain cedar sheds water and resists cupping better than flat-grain boards, which is worth paying for on a wall that gets direct weather. Fastener choice is a smaller but real factor, since standard steel fasteners streak and corrode in a wet climate, and corroded fasteners eventually loosen boards and let water behind them.
Finally, the wall assembly behind the siding matters as much as the siding itself. A rainscreen gap — a thin ventilated air space between the cedar and the weather-resistant barrier — lets bulk water drain and the wood dry from both sides. Cedar installed tight against sheathing with no gap traps moisture against the back of the boards, and is the most common cause of siding that rots from the inside out while looking fine from the street.
Whatcom County is not hit by hurricanes or tropical storms, and homeowners moving here from other regions sometimes underestimate what does apply. The defining condition is duration, not intensity. Bellingham, Ferndale, Lynden and the surrounding area get a long, low-intensity wet season where siding can stay damp for days or weeks without a real drying window, especially on north- and east-facing walls that get little direct sun.
That persistent dampness is what feeds moss and algae growth, which shows up as dark green or black staining, most often on shaded walls, under eaves, and near overhanging trees. Moss holds moisture directly against the wood surface and against fasteners, and left alone for years it does contribute to localized rot, particularly at butt joints and cut ends where the grain is exposed.
Homes closer to the water, in Blaine, Birch Bay, and the Semiahmoo area, deal with an added factor: wind-driven rain coming off the bay. Wind pushes rain sideways and up under laps and trim that would stay dry in a calmer inland location, so west- and northwest-facing walls on waterfront and near-waterfront properties tend to need more frequent finish maintenance and more careful flashing at windows, doors, and trim boards.
Washington's state energy code is a less obvious factor but a real one. Current code pushes toward continuous exterior insulation and tighter wall assemblies, which improves energy performance but changes how a wall dries. A cedar-sided wall built to current code needs a properly detailed rainscreen and vapor-permeable barrier to dry correctly; skipping that detail to save cost is a common source of hidden moisture problems in newer builds and in re-sides done without updating the assembly.
Plan on refinishing cedar siding on a cycle, not on an as-needed basis. In most of Whatcom County that means inspecting the finish every year and expecting to recoat every three to five years, sooner on south- and west-facing walls that see more weather, and sooner still on waterfront properties near Blaine or Birch Bay.
Yes — in this climate a set schedule works better than waiting for visible failure, because by the time cedar looks obviously weathered the finish has usually already stopped protecting the wood. Semi-transparent stains generally need attention every three to five years here, solid stains and paint somewhat longer, but shaded and water-facing walls should be checked annually regardless of finish type.
It can be, but it needs more disciplined maintenance than the same siding would need further inland, because of the added wind-driven rain off the water. Homeowners in these areas should budget for more frequent finish upkeep and pay particular attention to flashing and trim details on the walls that face the bay.
Shingles have more overlap and shed water in more layers, which can help in high-exposure spots, but they also have more edges and joints where moisture can get in if installation is sloppy. Lap siding is simpler to install correctly and to inspect, and in practice the quality of installation and finish maintenance matters more than the choice between the two.
Both. In the short term it is mostly a cosmetic and slip-hazard issue, but moss left in place for years holds moisture against the wood and fasteners continuously, and that sustained dampness is a real contributor to rot at joints and fastener points over time. It is worth removing rather than ignoring.
If you are trying to figure out whether your current cedar siding has years of life left in it, or is quietly failing behind a coat of paint, Alpine Exteriors inspects siding on homes throughout Bellingham, Ferndale, Lynden, Blaine, and Birch Bay and can tell you honestly what condition it is in and what it would take to extend its life. Whether that means a maintenance plan, targeted repairs, or a conversation about re-siding with a proper rainscreen assembly, Alpine Exteriors can walk the property with you and lay out the real options before anything is decided.