Custer isn't an incorporated city, so building permits for siding work there come from Whatcom County Planning & Development Services (PDS) in Bellingham, not from a local town hall. Whether you actually need one depends on the scope of the job — a straightforward re-side over existing sheathing is treated differently than a project that opens up the wall, changes the weather-resistive barrier, or touches structural framing.
Whatcom County operates under the Washington State Building Code, which is the state's adopted version of the International Residential Code with Washington-specific amendments. For unincorporated communities like Custer, Kendall, Sumas Prairie, and the rural stretches around Ferndale, PDS is the single point of contact for permitting, plan review, and inspections. That's different from homes inside Bellingham, Ferndale, Lynden, or Blaine city limits, where the city's own building department handles the same functions. If you own property near the Custer/Ferndale line, it's worth confirming which side of that boundary your parcel actually sits on before you call anyone — the jurisdiction, fee schedule, and inspector are not interchangeable.
In general terms, a siding permit tends to get triggered when the work goes beyond a cosmetic swap. Re-cladding a wall with the same type of siding, over sound sheathing, without disturbing the weather-resistive barrier, is often treated as minor work. But once a project involves removing siding down to the studs, replacing damaged sheathing, installing a new house wrap or rain screen system, or re-flashing around windows and doors, most jurisdictions — including Whatcom County — expect a permit, because those are the exact assemblies that keep water out of the wall cavity. Larger jobs, or ones bundled into a broader remodel that also touches windows, decks, or additions, almost always require one. If the project reaches a certain percentage of the exterior wall area being opened up, the Washington State Energy Code can also come into play, since re-siding that exposes the wall assembly is often the trigger point for bringing insulation and continuous insulation requirements up to current code, even on an older house that wasn't built to today's standard.
Custer sits close to Bellingham Bay and the Strait of Georgia, and that proximity matters more for siding than most homeowners expect. Wind-driven rain coming off the water doesn't just fall straight down — it gets pushed sideways into wall assemblies, which is why the details inspectors care about (head flashing over windows, kick-out flashing at roof-wall intersections, properly lapped weather-resistive barrier, a functioning rain screen gap) aren't bureaucratic box-checking. They're the difference between a wall that sheds water and one that slowly saturates behind the cladding. Whatcom County's persistent damp season, running long and grey for much of the year, also feeds moss and algae growth on north- and west-facing walls that stay shaded and slow to dry. That growth holds moisture against the siding surface, and over years it can contribute to wood rot in fiber cement trim, cedar siding, or any wood-based fascia and rim joist material — which is exactly the kind of hidden damage a sheathing inspection is meant to catch before it gets covered back up.
Freeze-thaw cycling is a real factor in the Whatcom County foothills — up toward Kendall, Deming, and the Mount Baker corridor — where repeated freezing and thawing can work at cracks in poorly sealed siding joints. Custer itself sits in the lowland coastal plain rather than the foothills, so it sees fewer hard freeze-thaw cycles than communities closer to the mountains, but it isn't immune to a cold snap followed by a thaw, and any existing gaps in caulking or flashing are what that cycle exploits. None of this is hurricane country, and there's no wind-mitigation inspection or product-approval paperwork like you'd see in a coastal hurricane zone — the concerns here are entirely about sustained wet weather, wind-driven rain, and slow moisture intrusion rather than sudden high-wind events.
Start by calling or emailing Whatcom County Planning & Development Services before any material shows up on site, and describe the scope honestly — whether sheathing is coming off, whether the house wrap is being replaced, and roughly how much of the exterior is involved. Get the permit determination in writing or as a reference number, not just a verbal opinion from whoever answers the phone that day, since scope tends to expand once a contractor is actually behind the old siding and finds rot or damaged sheathing that wasn't visible beforehand.
Alpine Exteriors works under Washington contractor license ALPINI751OW and handles the permit conversation with Whatcom County directly on jobs that call for one, rather than leaving a homeowner to sort out jurisdiction and paperwork mid-project. That said, permitting isn't free and it isn't instant — plan for review time and don't assume a same-week start on a job that legitimately needs county sign-off, especially during the busier spring and summer months when PDS has more applications in the queue.
Not always. A like-for-like re-side over sound, undisturbed sheathing is frequently treated as minor work, but the moment sheathing is replaced, the weather-resistive barrier is changed, or the job is paired with other exterior work, Whatcom County Planning & Development Services generally expects a permit. The honest answer is to ask PDS about your specific scope rather than assume either way.
Since Custer is unincorporated, it's Whatcom County Planning & Development Services in Bellingham, not a city building department. If your address is close to the Ferndale or Blaine city limits, it's worth double-checking your parcel's jurisdiction first, because the two systems don't share permit records or inspectors.
The key inspection typically happens before the new cladding covers the wall — checking the weather-resistive barrier lap and fastening, flashing at windows, doors, and roof intersections, and any sheathing repairs. A final inspection follows once the siding is installed and trim work is complete. These checkpoints exist specifically because wind-driven rain off Bellingham Bay and the Strait finds any gap in that assembly over time.
Timelines vary with the county's current review volume and how complete the application is when it's submitted, so there's no fixed number of days to promise. Simpler re-siding scopes generally move faster than jobs that also touch structural repairs or energy code compliance, but building in a buffer for review time — rather than assuming an immediate start — avoids scheduling headaches.
If you're planning a siding project in Custer or anywhere else in Whatcom County — Bellingham, Ferndale, Lynden, Blaine, Birch Bay, Sudden Valley, or the islands — Alpine Exteriors can walk the property, tell you honestly whether the scope you're picturing needs a Whatcom County permit, and handle that process alongside the actual installation. Reach out to Alpine Exteriors (WA contractor license ALPINI751OW) for a straightforward assessment before any siding comes off the wall.