Siding Inspection Checklist for the Lettered Streets, Bellingham

Updated August 2026 · Alpine Exteriors · WA contractor license ALPINI751OW

Why This Checklist Matters in the Lettered Streets

The Lettered Streets neighborhood is one of Bellingham's oldest residential pockets, full of Craftsman bungalows, foursquares, and turn-of-the-century cottages sitting on narrow lots under a mature tree canopy. A lot of that character comes from original wood lap siding, and even homes that were re-sided decades ago are now old enough that their trim, caulk, and flashing are due for a hard look. That combination — older wall assemblies, dense shade, and a short walk to Bellingham Bay — makes this neighborhood a little more demanding on siding than a newer subdivision out past the interurban trail.

Three things drive most of the siding problems we see on Lettered Streets calls. First, Whatcom County's rain isn't dramatic, but it's persistent — long stretches of drizzle keep wall surfaces damp for days at a time, which is exactly what wood rot and mildew need. Second, wind off the bay and the Strait of Georgia can drive that rain sideways into south- and west-facing walls, forcing water into joints and laps that would stay dry in a calmer climate. Third, the tree cover that makes these streets so pleasant to walk also blocks sun and airflow, so north-facing and shaded walls stay wet longer and grow moss and algae faster than sunnier elevations. Add in the occasional hard freeze that rolls down from the foothills in January, and any water that's already worked its way behind siding or into a cracked board gets a chance to expand and do real damage.

None of this means Lettered Streets siding is fragile — well-maintained wood and fiber cement siding in this neighborhood can last a long time. It does mean a once-a-year walk-around, ideally before the fall rains settle in, catches small problems while they're still cheap to fix. This checklist is built around what actually fails on homes in this specific part of Whatcom County, not a generic list written for a different climate.

The Checklist

Painted or stained wood siding and trim

• Look for peeling, bubbling, or alligatored paint on lap siding — failed paint lets water reach bare wood underneath.
• Press a screwdriver tip gently into window sills, corner boards, and the bottom few courses of siding — soft or spongy wood signals rot that's already started.
• Check for boards that have cupped, split lengthwise, or pulled away from the wall — these gaps let wind-driven rain get behind the siding instead of running off it.
• Scan for dark staining running down from nail heads — that's usually a sign the nail or the wood around it is holding moisture.

Moss, algae, and general staining

• Check north-facing and tree-shaded walls for green or black growth — these areas dry slowest and are where moss takes hold first in this climate.
• Look at the underside of window sills and porch soffits for black streaking — this points to trapped moisture and poor drying, not just dirt.
• Note any siding sections that stay visibly damp long after a dry day — slow-drying siding is a preview of where rot will show up next.

Caulk, flashing, and butt joints

• Inspect caulk lines around windows, doors, and where trim meets siding — cracked or missing caulk is one of the most common entry points for wind-driven rain off the bay.
• Check that flashing above windows, doors, and any horizontal trim boards is intact and properly lapped — flashing that's rusted, bent, or missing lets water run straight into the wall.
• Look at vertical butt joints where two siding boards meet end to end — open or poorly caulked joints are a direct path for water behind the wall.
• Check flashing where a porch roof or bay window meets the main wall — these transitions take the brunt of wind-driven rain and are common failure points on older homes.

Foundation line and lower courses

• Confirm siding stops several inches above grade or hard surfaces — siding that touches soil, mulch, or a concrete walkway wicks up moisture constantly.
• Check for splash-back staining on the lowest courses from roof runoff or ground-level sprinklers — repeated wetting here accelerates rot faster than anywhere else on the wall.
• Look for gaps between the foundation and the bottom siding course where pests or moisture could enter — a small gap here is easy to seal now and expensive to ignore.

Windows, porches, and roof intersections

• Check that siding fits snugly around window and door trim with no visible gaps — gaps here are a direct route for both water and drafts.
• Inspect where siding meets porch roofs, dormers, and chimneys — these intersections rely entirely on flashing, and older homes often have flashing that's been painted over and forgotten rather than replaced.
• Look at gutters and downspouts for overflow staining on the siding below — a clogged or undersized gutter throws extra water at the wall every time it rains hard.

Fasteners and panel attachment

• Check for popped, backed-out, or rusted nails and screws — exposed fasteners rust quickly in this climate and each one is a small water entry point.
• On any fiber cement or vinyl sections added later, verify panels are still flat against the wall with no visible warping or waviness — this can indicate a moisture or attachment problem underneath.

What to Do If an Item Fails

Not every failed item means a full re-side. Start by photographing and dating what you find so you can track whether it's getting worse. Small, contained issues — a cracked caulk line, a single popped nail, light surface moss — are reasonable to handle yourself: scrape and re-caulk with a quality exterior sealant, re-set or replace the fastener, and treat moss with a gentle wash rather than a pressure washer, which can force water under siding laps and cause more harm than the moss itself.

Soft wood, active rot, or staining that keeps returning after cleaning is a different situation. Painting over rotten wood or caulking over a gap without finding out why water is getting in just traps the moisture and hides the problem until it's bigger. If you find soft wood, cut back to solid material where practical to see how far it extends before deciding whether it's a spot repair or a sign of a larger area affected. Whatever you find, prioritize repairs before the wet season sets in — a small gap that sits open through a Whatcom County winter tends to be a much bigger repair by spring.

When to Call a Professional

Bring in a licensed contractor when rot extends beyond a board or two, when you find soft or damaged sheathing behind the siding, when flashing needs to be replaced rather than just re-caulked, or when the affected area is above the first floor and requires safe access. On older Lettered Streets homes especially, matching existing wood profiles, working around original trim details, and figuring out whether an issue is isolated or a sign of a wider moisture problem in the wall assembly is easier to get right the first time with an experienced eye. Alpine Exteriors, licensed in Washington under ALPINI751OW, inspects siding on homes throughout Whatcom County — Bellingham, Ferndale, Lynden, Blaine, Birch Bay, Sudden Valley, and the islands — and can tell you plainly whether you're looking at a repair or something that warrants a broader conversation.

FAQ

How often should siding on a Lettered Streets home be inspected?

Once a year is a reasonable baseline, ideally in late summer or early fall before the region's rainy stretch sets in, with a quick follow-up check after any unusually windy storm off the bay. Older homes with original wood siding or trim benefit from a closer look, since small failures tend to compound faster on assemblies that are already decades old.

Can I keep original wood siding on an older Lettered Streets home, or does it need to be replaced?

In many cases wood siding in reasonably sound condition can be repaired, spot-replaced, and repainted rather than torn off wholesale, which preserves the look of the home and is often less expensive than a full re-side. The deciding factor is how much of the wood is actually still solid — if rot is limited to a few boards, targeted repair usually makes sense; if moisture has been getting behind the siding for years, a fuller assessment is worth doing before committing either way.

Does re-siding a home here trigger Washington State Energy Code requirements?

If a re-siding project involves removing siding down to the sheathing, it's a reasonable point to evaluate the wall's insulation and air-sealing against the Washington State Energy Code, since code compliance is generally assessed when a wall assembly is opened up as part of the work. A contractor can walk through what applies to your specific scope before work starts, since a simple repair and a full tear-off are treated differently.

Roughly what does siding repair versus replacement cost in this area?

Spot repairs — a section of rotten trim, a few replaced boards, re-caulking and re-flashing a problem area — often run in the low hundreds to a couple thousand dollars depending on access and extent. A fuller re-side of a typical Lettered Streets home is a much larger investment, commonly in the tens of thousands, with the range driven by siding material, how much of the substrate needs repair, and the complexity of the home's trim and rooflines. An in-person inspection is the only reliable way to know which end of that range applies to your house.

Get an Inspection Before the Rain Sets In

A siding walk-around takes an afternoon and can save a homeowner from a much larger repair down the road, especially on a home that's been standing through Whatcom County winters for a century or more. If this checklist turned up soft wood, open joints, or flashing you're not sure about, Alpine Exteriors is available to take a closer look, explain what's actually going on with your walls, and lay out honest options — repair, partial re-side, or full replacement — for homes throughout Bellingham, Ferndale, Lynden, Blaine, Birch Bay, Sudden Valley, and the islands.