Sehome sits on the hill above downtown Bellingham, wrapped around Western Washington University, with mature Douglas fir and bigleaf maple canopy over streets of mid-century ramblers, older Craftsman-era houses, and newer infill construction. That tree cover is part of what makes the neighborhood pleasant to live in, and it's also exactly why so many Sehome homes fight a losing battle with moss and algae on their north walls. Add in eight or nine months a year of steady Pacific Northwest rain, wind-driven moisture off Bellingham Bay and the Strait of Georgia on exposed west- and south-facing elevations, and the freeze-thaw cycles that show up in the foothills once winter arrives, and siding choice here is not a cosmetic decision. It's a building-envelope decision. This page walks through what actually holds up on Sehome houses, what tends to fail early, and what the Washington State Energy Code has to say about the wall assembly underneath whatever cladding you choose.
For most Sehome homes, fiber cement siding is the material we recommend most often, followed closely by engineered wood siding on homes where budget is the deciding factor and the walls are well protected by roof overhangs. Cedar still has a place on homes where the owner wants the traditional Pacific Northwest look and is willing to keep up with maintenance, and vinyl remains a reasonable, budget-conscious option on simpler ramblers as long as expectations about its limitations are realistic. Metal siding shows up less often in this neighborhood but earns consideration on modern-style remodels and on homes with heavy shade where moss resistance matters most.
| Material | Best for in Sehome | Main thing to watch |
|---|---|---|
| Fiber cement | Shaded lots, west/south exposures, long-term owners | Higher upfront cost, needs periodic repainting |
| Engineered wood | Well-protected walls, tighter budgets | Edge sealing must be done correctly at install |
| Cedar | Historic character, owners who enjoy maintenance | Requires the most upkeep of any option here |
| Vinyl | Simple ramblers, rental properties, lowest budgets | Can crack in a hard freeze, limited color life |
| Metal | Modern remodels, heavy-shade lots, moss-prone walls | Denting risk, higher material cost |
We didn't rank these products against some generic national standard. We ranked them against what actually happens to a wall assembly on a hill in Bellingham. The criteria that mattered most:
Fiber cement — plank, shingle-style panels, or trim — is a mix of cement, sand, and cellulose fiber pressed into boards that are then factory-primed or factory-finished. It's the material we install most often in Sehome, and for good reason: it doesn't rot, it doesn't feed moss the way wood fiber does, and it holds a straight, tight reveal against a wall for decades when installed correctly.
Pros: Excellent resistance to rot and insect damage since there's no wood fiber for moisture to work into. Handles wind-driven rain well when lapped and flashed properly. Holds paint far longer than wood, which matters on the shaded, damp walls that dominate parts of this neighborhood. Non-combustible, which some Sehome homeowners value given the proximity of dry brush on the hillside in late summer even though this region isn't a high wildfire zone. Available in styles that match both older Craftsman detailing and simpler mid-century ramblers.
Cons: It's heavier and more labor-intensive to install than vinyl or engineered wood, which shows up in the labor portion of the bid. It has to be field-cut with proper dust control, since the material contains silica. It still needs repainting on a cycle — typically longer than wood, but it's not maintenance-free. And because it's rigid, it doesn't flex the way vinyl does around minor settling, so proper fastening matters.
Rough cost range: Generally mid-to-upper range compared to the other options here, with the spread depending heavily on trim detail, factory finish versus field paint, and how much of the old siding and any rot repair is involved in tear-off.
Engineered wood products, most commonly sold under names like LP SmartSide, use wood strands bonded with resin and coated with a resin-saturated overlay, then factory-primed. It's a reasonable middle ground between the cost of vinyl and the durability of fiber cement.
Pros: Lighter and generally faster to install than fiber cement, which can bring labor cost down. Takes paint well and holds a wood-grain look some owners prefer over the flatter texture of fiber cement. Reasonably good moisture resistance as a manufactured product, assuming the factory-applied seal on all edges is intact.
Cons: The entire moisture performance of this product depends on cut edges being field-sealed with the manufacturer's specified sealant at install, and on caulking being maintained at every seam. Skip that step, or let the caulk fail years down the road without recaulking, and water gets into the wood strand core, where it swells and delaminates — we've seen this on homes near Sehome where the original install cut corners on edge sealing. It's more vulnerable than fiber cement on heavily shaded, slow-drying walls, so we tend to steer it toward better-protected elevations rather than the shadiest north walls under the tree canopy.
Rough cost range: Generally below fiber cement, making it a common choice when a homeowner wants better performance than vinyl without the full fiber cement budget.
A fair number of older homes in Sehome still wear their original cedar bevel or shingle siding, and some owners specifically want to replace like-for-like or install new wood siding for the look. It's a legitimate choice, but it comes with the most demanding maintenance schedule of anything on this list.
Pros: Authentic look that matches the neighborhood's older housing stock, particularly the Craftsman and early 20th-century homes. Repairable in sections rather than requiring full panel replacement. Renewable material with a long track record in this climate when properly maintained.
Cons: Untreated or poorly finished cedar is the material most prone to moss and algae growth on shaded Sehome walls, and it's also the most susceptible to rot where moisture sits against the wood — around window trim, at the bottom courses near grade, and behind gutters that overflow in a hard rain. It needs refinishing (stain or paint) far more often than fiber cement or engineered wood, and skipping a cycle on a damp, shaded wall can mean rot repair the next time around. It's also generally the most expensive option per square foot once you factor in finish quality.
Rough cost range: Typically the highest of the options covered here, and ongoing maintenance costs should be budgeted as a real, recurring line item, not an afterthought.
Vinyl remains common on simpler ramblers and rental properties in Sehome, mostly because of upfront cost. It's not a bad product for this climate in general terms, but it has real limits that matter here.
Pros: Lowest material and installation cost of the mainstream options, with no repainting required. Doesn't rot, since there's no organic material in the panel itself. Wide color and profile selection, including options that mimic wood grain reasonably well from a distance.
Cons: In a hard freeze — which does happen most winters in the foothills and on cold, clear nights around Bellingham — vinyl becomes more brittle and can crack on impact, more so than fiber cement or engineered wood. Colors fade over time, especially darker tones, and vinyl can't be repainted the way wood-based sidings can, so a faded wall means full replacement rather than a repaint. It also relies more heavily on a properly installed weather-resistant barrier and flashing behind it, since the panels themselves are not a sealed water barrier — they're designed to let some water through to a drainage plane. On a wind-driven-rain wall facing the bay, that underlying detail matters as much as the panel itself.
Rough cost range: Generally the lowest upfront cost of the materials discussed here, which is why it remains popular on budget-driven projects.
Metal panel siding — typically steel or aluminum with a factory coating — shows up less often in Sehome's traditionally styled housing stock, but we're installing more of it on modern remodels and additions, and on homes where moss resistance is the top priority.
Pros: Sheds moss and algae better than any wood-fiber product because there's no organic material for spores to establish on, which makes it worth considering on the shadiest, dampest lots in the neighborhood. Handles wind-driven rain well with proper panel overlap and sealed penetrations. Doesn't rot and holds its finish a long time without repainting.
Cons: It dents more easily than fiber cement, which matters on a tree-heavy street where falling branches are a real possibility. It reads as a distinctly modern material, which doesn't suit every home's architecture — it looks right on a contemporary remodel and out of place on a 1920s Craftsman. It also tends to be one of the pricier options, and panel or trim damage typically means replacing the affected section rather than a simple spot repair.
Rough cost range: Generally comparable to or above fiber cement, depending on gauge and finish.
A few choices come up often enough in older Sehome homes that they're worth calling out directly. Original 1970s-era T1-11 plywood siding, still present on some ramblers in the neighborhood, is a common source of rot once the factory finish wears through and water starts wicking into the panel edges and seams — if a home still has its original T1-11, it's almost always past due for replacement rather than another repaint. Traditional hard-coat stucco is also a poor fit for this climate generally; it's rare in Sehome for good reason, since it doesn't drain well against a wood-frame wall in a climate with this much sustained moisture, and cracks that develop over time let water track behind the assembly where it can sit for months. And regardless of material, any re-side that skips a proper drainage gap and doesn't address the Washington State Energy Code's continuous insulation requirements for the wall assembly is setting up the next thirty years for problems, whatever the exterior product looks like on install day. The cladding is only as good as what's behind it.
It helps, but it doesn't eliminate the issue entirely — moss and algae need moisture and a surface to colonize, and shaded north walls under tree canopy will always stay damper longer than sun-exposed walls. Switching from wood or older vinyl to fiber cement or metal reduces how much the growth digs into the surface and makes cleaning less damaging to the material, but trimming back overhanging branches and keeping gutters clear does more for prevention than the siding material alone.
The specifics depend on your project scope and whether it triggers a full envelope review, but the Washington State Energy Code generally pushes toward continuous insulation on exterior walls beyond what older Sehome homes were built with, especially on major re-sides. We look at this on every project so the wall assembly underneath the new siding actually meets current code rather than just looking good from the street.
Sometimes, but we're cautious about it in this neighborhood. If the existing siding or the sheathing behind it has any rot — common on older homes with original wood or T1-11 siding — covering it over just hides a problem that keeps getting worse. We typically recommend a tear-off so we can inspect the sheathing, address any moisture damage, and install a proper drainage gap, rather than layering new material over an unknown condition.
It varies with the size of the home, the amount of trim detail, and whether we find rot that needs repair once the old siding comes off, which is common on homes over 30 years old in this neighborhood. We give homeowners a realistic timeline once we've done a hands-on assessment rather than a generic estimate, since guessing at rot repair scope before opening up the wall tends to be wrong in one direction or the other.
Every Sehome property is a little different — shade coverage, exposure to wind-driven rain off the bay, age of the original siding, and how the wall assembly was built all factor into the right recommendation. Alpine Exteriors has worked on homes throughout this hillside neighborhood and across Whatcom County, from Bellingham and Ferndale to Lynden, Blaine, Birch Bay, and Sudden Valley, and we'll walk your property with you, look at what's actually happening behind the current siding, and give you a straight answer about what material fits your home, your budget, and this climate. Alpine Exteriors is licensed in Washington under contractor license ALPINI751OW — reach out for a walkthrough and a written estimate before you decide.