Home Exterior Inspection Checklist for Friday Harbor and San Juan County Homes

Updated August 2026 · Alpine Exteriors · WA contractor license ALPINI751OW

Why This Checklist Matters in San Juan County

San Juan Island sits out in the Salish Sea, and the house you're inspecting has to shrug off a climate that mainland Skagit and Whatcom County homes don't fully share. Winters here bring long stretches of steady, soaking rain rather than short heavy downpours, and that slow saturation is what finds the weak spot in a roof, a flashing detail, or a grade that slopes the wrong way. Homes tucked under Douglas fir, madrona, and cedar canopy on the island's north and west sides stay shaded for much of the day, and that shade keeps roofs damp long after a storm passes, which is exactly the condition moss and roof algae need to take hold. Once moss establishes on a roof, it holds moisture against the shingles or shakes and can lift edges enough for wind-driven rain to work underneath.

Wind is the other factor worth naming directly. Friday Harbor and the rest of San Juan Island face open exposure across Haro Strait and San Juan Channel, and gusts off that open water put real load on ridge caps, gutter fasteners, and anything loosely attached to a roof or wall. This is not hurricane country and doesn't need to be treated as such, but a steady 30 to 40 mph blow off the water a few times a winter is enough to peel back a shingle that was already marginal, or work a loose downspout bracket free of the wall.

Salt air is the piece that catches a lot of homeowners off guard, especially those who moved from inland Washington. Even a house set back from the water sees salt-laden air drift across the island, and that air is quietly corrosive to exposed metal fasteners, gutter hangers, flashing, and hardware over the years. A fastener that would last decades in Sedro-Woolley can rust and weaken faster on San Juan Island, which is one more reason a slow, deliberate inspection matters more here than it might elsewhere.

Snow and ice are occasional rather than routine on the island, but they do happen most winters, usually as a wet, heavy snowfall or a hard freeze after a rain event. Ice that forms in a clogged gutter or at a roof edge where insulation is thin can back water up under shingles, so it's worth checking those areas even in a year when snow barely sticks. Any window, door, or insulation work you're evaluating or planning should also be measured against the Washington State Energy Code, which sets the performance bar for glazing, air sealing, and insulation values on this side of the state.

There's also a practical, non-weather reality to inspecting a home on San Juan Island: nearly everything runs through the ferry system. Materials, specialty crews, and even routine service calls have to be scheduled around ferry sailings out of Anacortes, and that adds lead time you don't deal with on the mainland. A small roof leak that would get a same-day patch in Mount Vernon might take a few extra days to reach on the island simply because of logistics. That's not a reason to skip inspecting — it's the reason to inspect early and often, so small problems get caught while they're still small and schedulable, not urgent.

The Checklist

Work through each group below at least once a year — early fall, before the winter rains set in, is the ideal time on San Juan Island.

Roof and Chimney

• Shingles or shakes that are cupped, cracked, or missing — a lifted or missing piece is a direct path for wind-driven rain to reach the roof deck.
• Moss or dark algae streaking, especially on north- and west-facing slopes under tree cover — moss holds moisture against roofing material and can lift edges over time.
• Flashing around the chimney, skylights, and roof-to-wall joints — these transitions are the most common source of slow leaks during long rain events.
• Chimney cap, crown, and mortar joints, if masonry — salt air and freeze-thaw cycles can erode mortar faster near the water.
• Ridge caps and hip lines for lifted or loose sections — this is where wind off the water applies the most uplift force.
• Attic underside for water staining, dark spots, or daylight showing through the decking — often the first sign of a roof problem before it's visible from the ground.

Gutters and Downspouts

• Needle and leaf buildup, especially under fir and cedar cover — clogged gutters back water up under the roof edge instead of carrying it away.
• Gutter hangers and fasteners for rust or looseness — salt air accelerates corrosion on exposed metal hardware.
• Downspout extensions and splash blocks — water dumped too close to the foundation is a common cause of crawlspace moisture on island lots.
• Gutter seams and end caps for drips or staining below — a small seam leak can streak and stain siding over a single wet winter.

Siding, Trim and Fascia

• Caulking and sealant at trim joints, window edges, and wall penetrations — gaps let wind-driven rain track behind the siding.
• Soft or discolored fascia and soffit boards — these areas trap moisture from gutter overflow and are slow to dry in shaded, humid conditions.
• Paint or stain that's peeling, chalking, or thin — a failing finish exposes wood or fiber cement to the wet-dry cycling that speeds up rot and cracking.
• Metal siding fasteners and trim screws for rust bleed — a small orange streak below a fastener is an early corrosion warning.
• Gaps where different siding materials meet, such as at corners or additions — these transitions are common weak points for water intrusion.

Windows and Doors

• Glazing seals and any fogging between panes — a failed seal on an insulated unit is a performance issue as much as a cosmetic one under the Washington State Energy Code.
• Weatherstripping around all operable windows and doors — worn stripping lets in both drafts and moisture during wind-driven rain.
• Sill and threshold caulking — this is a frequent entry point for water on doors facing the prevailing weather.
• Hardware operation, including locks and hinges — salt air can stiffen or corrode exterior-grade hardware faster than expected.

Decks, Porches and Outdoor Structures

• Deck boards for soft spots, splintering, or gaps that have widened — these often mean moisture has been sitting in the wood grain.
• Ledger board attachment to the house — this connection carries structural load and is worth a close look anywhere heavy rain and standing water are common.
• Railing posts and connections for movement — wind gusts off the water put repeated stress on railings over a season.
• Fasteners and hardware for rust staining — as with roofing and gutters, salt air shortens the working life of exposed metal on decks.
• Stain or sealant coverage on exposed wood — bare or thinning finish leaves wood open to the region's long wet season.

Foundation, Crawlspace and Drainage

• Grading around the foundation — soil should slope away from the house so winter rain doesn't pool against the walls.
• Crawlspace vents and ground moisture or standing water — persistent island rainfall can raise water tables on some lots, especially in low-lying areas.
• Foundation cracks, even hairline ones — freeze-thaw cycles during a cold snap can widen a small crack over a winter.
• Downspout discharge points relative to the foundation — water should be carried well clear of the house, not dumped at the base of a wall.

What to Do if an Item Fails

Not every failed item is an emergency, and it helps to sort what you find before deciding on next steps. Cosmetic issues, like chalking paint or light moss on a shaded gutter, can usually wait for the next scheduled maintenance visit, though they're worth noting so they don't get forgotten. Functional issues, such as a loose gutter hanger, a gap in caulking, or a soft deck board, deserve attention within the season, before the next heavy rain or wind event turns a small gap into a bigger repair. Anything that suggests active water intrusion, structural movement, or a compromised roof deck should move to the top of the list and get addressed as soon as scheduling allows.

For minor items, a homeowner comfortable on a ladder can often handle gutter clearing, re-caulking a trim joint, or touching up a small area of peeling paint. For anything involving roof access, structural connections like a deck ledger, or repeated moisture intrusion, it's worth getting a second set of eyes before deciding on a fix, since the visible symptom and the actual source of a leak aren't always in the same spot. Because of the island's ferry-dependent logistics, it's also worth flagging repairs early rather than waiting until a small issue becomes urgent — booking a contractor with lead time gives more flexibility on scheduling than waiting for a leak to force the issue.

When to Call a Professional

Some findings are reasonable to monitor for a season; others are worth a professional opinion right away. Call a contractor if you see daylight through the roof deck from the attic, active water staining that's spreading or fresh after a recent storm, soft or spongy roof decking underfoot, a deck ledger board that shows separation or rot, or foundation cracks that are widening or accompanied by door and window misalignment. It's also worth a professional look if you're not confident distinguishing surface moss from an underlying shingle problem, since pulling moss off a roof yourself can do more damage than leaving it for a trained crew to remove properly. Alpine Exteriors works across Skagit, Island, and Whatcom counties and reaches San Juan Island by ferry out of Anacortes for inspections and repair work, so a call doesn't require the homeowner to solve the logistics alone.

One honest drawback worth naming: because San Juan Island depends on ferry scheduling for materials and crews, response times for on-island work are typically longer than for a job in Mount Vernon or Burlington, and larger material orders may carry added freight cost. Planning inspections and repairs a season ahead, rather than waiting for a crisis, is the most effective way to work around that reality.

Friday Harbor Exterior Inspection FAQ

How often should a San Juan Island home get a full exterior inspection?

Once a year is a reasonable baseline for most homes, ideally in early fall before the winter rains arrive, with a lighter check-in after any unusually strong wind event off the Strait. Homes with heavy tree cover or a lot of roof shade may benefit from checking gutters and moss growth twice a year, since debris and moisture build up faster under a fir or cedar canopy than on an open lot.

Why does moss keep coming back on my roof even after I clean it off?

Moss returns when the underlying conditions that let it grow in the first place are still present, most often shade and slow-drying moisture on a north- or west-facing slope. Scraping moss off the surface without addressing airflow, overhanging branches, or a roof's ability to dry between rain events usually means it comes back within a season or two.

Do I need to worry about hurricane-rated materials on San Juan Island?

No — this region doesn't see hurricanes, and hurricane-rated products aren't part of the local building requirements. What does matter here is wind resistance suited to the gusts that come off Haro Strait and San Juan Channel, proper fastening at ridges and edges, and, for windows and doors, meeting the performance standards set by the Washington State Energy Code.

Is it more expensive to get exterior work done on San Juan Island than on the mainland?

It can be, mainly because of ferry freight on materials and the added scheduling time for crews to travel to and from the island, rather than because labor or material costs themselves are higher. Getting an inspection done early and bundling smaller repairs into one visit is usually the most cost-effective way to manage that added logistics cost.

Ready to Get Your Exterior Checked

A thorough walk-around once a year catches most problems while they're still small, inexpensive fixes rather than emergency repairs. If you'd rather have a trained crew go through this checklist for you, Alpine Exteriors, Washington contractor license ALPINI751OW, serves Skagit, Island, and Whatcom counties and travels to Friday Harbor and the rest of San Juan Island by ferry for inspections, roofing, gutters, siding, windows, and deck work. Reach out to schedule a fall inspection before the winter rains set in, or to get a second opinion on anything you found on this list.