The Long Beach Peninsula is a strip of sand between the Pacific and Willapa Bay. The City of Long Beach is its commercial center, with the boardwalk, Pacific Avenue, and a grid of vacation lots that look roomy until you account for wind, septic, and the five-foot separation from the existing house. From our factory in Battle Ground, near Vancouver, WA, the module doesn’t just go up I-5. It turns west, usually on US-30 to the Astoria–Megler Bridge and then north on US-101, or the longer inland route through Raymond, and finishes on a peninsula road with sand, wind, and often a narrow lot.
Wolf has built many ADUs on this peninsula, including a vacation home in Long Beach the owners built instead of staying in an RV, and a tiny home in nearby Ocean Park planned as a cabin or rental with a covered porch.
City of Long Beach or Pacific County
The peninsula has more than one permit office. The City of Long Beach reviews lots inside city limits. Pacific County reviews unincorporated land, including much of the Seaview edge, Ocean Park, and the dunes north of town. Ilwaco is its own city. Confirm the taxlot before you file.
Pacific County ADU rules depend on the parcel’s Land Use District, which sets setbacks and height, and eligibility isn’t the same across the county. Our Pacific County ADU guide is the place to start. The main limits from that summary (confirm Ordinance 145 and current amendments):
- No more than one accessory residential dwelling per lot of record.
- The ADU must be clearly subordinate to an existing principal single-family residence.
- The ADU may be no more than 1,200 square feet.
- An accessory structure should be separated from the primary building by at least five feet, with limited flexibility when certain conditions are met.
- The accessory dwelling and the land cannot be sold separately from the primary dwelling.
- Where a property has both a primary dwelling and an ADU, only one of the residential structures may be rented as a vacation rental, not both.
Setbacks and height follow the Land Use District rather than one countywide standard, so we confirm them for your property.
Inside Long Beach city limits, the city handles the building permit and local zoning overlay. HB 1337’s statewide UGA floor is covered in the Washington ADU laws guide. On the peninsula, though, wind, sand, septic, and the one-ADU-per-lot rule are usually what decide the project. Rules from Portland (800 square feet) or urban Clark County (two ADUs) don’t apply to a dune lot without checking the district.
Peninsula geography
The Long Beach Peninsula runs about twenty-six miles from Ilwaco north toward Leadbetter Point, and the City of Long Beach is only a slice of it. Ocean-side lots take the southwest wind and salt first. Bay-side lots on Willapa look calmer but can still be mapped floodplain, with different wave and drainage conditions. A lot two rows back from Pacific Avenue isn’t a dune lot, and a dune lot isn’t a Seaview pocket, so each one gets its own foundation plan.
Dune vegetation matters too. Removing it without a plan can cause environmental and sand-migration problems. If the lot is in a district with dune protections, the district will say so, and we check before proposing a pad on the last patch of grass.
Wind, sand, and the foundation
Coastal exposure is the main siting concern. Southwest wind, salt air, and sandy soil affect anchorage, drainage, and how the grade shifts after a winter. The evaluation covers soil conditions, setbacks, infrastructure limits, and environmental requirements. Wind speed and frost depth come from the engineer and current local code. We look at:
- Whether the pad is in a mapped flood or tsunami overlay (common on low peninsula lots).
- How the sand drains, and where stormwater goes.
- Whether a crawlspace, slab, or another foundation type suits the soil, subject to the engineer and the local inspector.
- Materials and finishes that hold up to salt air.
The covered porch on the Ocean Park job mattered because peninsula living means wet gear and a lot of time outside. The Long Beach vacation home used a Model F (~616 sq ft, 14×44) with custom trim, pine walls, and a patio and deck, as a code-built alternative to an RV. Both are factory-built homes that stay insulated and livable when a squall comes through.
Models under 1,200 square feet on a sandy lot
These are modular homes, not HUD (the federal standard for manufactured homes) manufactured. “Tiny home,” “coastal cottage,” and “ADU” usually describe the same modular dwelling.
- Model E (~616 sq ft, two bedroom). Our usual coastal choice when guests or a family need two bedrooms, and well under the 1,200 cap.
- Model K (~432 sq ft) for a one-bedroom rental or guest cottage, or when the truck path only fits a 12-foot module.
Larger plans like the Model J (~828 sq ft) or Model L (~984 sq ft) fit under the 1,200 cap, but width and delivery on peninsula streets often rule them out first. A 23- or 28-foot-wide home needs a very different crane and traffic plan than a 12-foot K.
Permits: Type I review
Pacific County ADU approval goes through a Type I review, which is administrative with no public hearing, under Ordinance 145 and amendments. Our summary doesn’t list fees, so confirm those with the county. The ADU must meet current local and state health code for potable water and wastewater. On rural and many peninsula parcels, that means proving septic capacity for a second dwelling early. City sewer, where available, needs its own adequacy letter. Don’t assume a vacation lot on sand has spare drainfield.
Septic on sand needs a designer who accounts for the water table, setbacks to water bodies, and bedroom count. A two-bedroom Model E plus a two-bedroom house is four bedrooms of load on the system. Count bedrooms the way Environmental Health does, not the way a real estate listing does.
City of Long Beach building permits are a separate local path for in-city lots. We still need a site plan showing the primary house, the five-foot separation, utilities, and the truck path from Pacific Avenue or the side street to the pad.
Vacation rental or long-term
Many peninsula owners start with a guest cottage in mind and then think about summer rental income. Pacific County’s rule is clear: only one of the two dwellings can be a vacation rental. If the main house is already a short-term rental, the ADU can’t be, and if the ADU is the STR, the house can’t be. Long-term rentals and family use are separate questions. Tell us the intended use on day one so the design matches what the ordinance allows.
The Long Beach case study was a vacation home for the owners themselves. The Ocean Park job was planned as a cabin or investment rental. Neither tells you whether your Land Use District allows short-term rentals, so we check that for your lot.
Delivery: the bridge, the wind, the last block
The home is built at the factory while permits and site work move forward on the peninsula, so it’s never framed in a 40-mph squall. Set day still depends on wind. If a gale is forecast, a crane on a sand lot gets rescheduled. We plan the route (the bridge or Raymond), staging, and whether the home is a single module or a two-piece set that has to be joined on site.
Ilwaco’s port and the Columbia River bar are south of town. Deliveries over the Astoria–Megler Bridge still have to pass through Ilwaco and then up the peninsula highway. Tourist weekends in July and the kite festival make street use harder, and January wind makes crane work harder, so we choose the season deliberately.
Overhead lines, dune grass, a cedar in the swing path, and parked tourist traffic in August are the usual last-block problems. Off-season sets are often easier on the street. Winter is wet and windy but still workable with careful planning.
Site work on a peninsula job usually means foundation excavation in sand, utility trenching, grading, and erosion control so the pad holds its shape through a storm. On set day we weather-seal the same day when we can, then finish the mechanical and plumbing tie-ins. Two-piece plans add a day to join the halves.
Warranty work is a longer drive than it is for a job in Chehalis. The same field crew still comes back, not a dealer network, and we schedule those visits knowing the distance.
Cost
On the peninsula, septic, sandy soil, wind anchorage, and long utility trenches can move the total more than finish choices. Factory construction makes the home price more predictable than building on site in the rain, but Pacific County Environmental Health reviews and fees still apply. See financing if you plan to use a HELOC or construction loan.
What the evaluation looks at
Bring the address, how you’ll use the unit (family, long-term, or vacation rental), and any septic as-built. We look at:
- City of Long Beach or Pacific County, and the Land Use District.
- The 1,200 sq ft cap and the five-foot separation from the primary house.
- Water and wastewater: septic capacity or sewer adequacy.
- Flood and coastal overlays.
- Truck path from US-101 to the pad, crane room, and wind exposure.
- Whether a short-term rental in the ADU would conflict with one in the house.
If you already know the drainfield is undersized, tell us up front so we can plan around it before you commit to a two-bedroom.
Ilwaco, Seaview, and Ocean Park
Ilwaco is a working harbor town with its own city hall. Seaview sits between Ilwaco and Long Beach and is often county. Ocean Park, farther up the peninsula, is where our porch-and-cabin case study is, and it’s outside Long Beach city limits. Astoria is across the river in Oregon, under a different state code. If your lot is in one of those places, its rules apply. If the reviewer is Long Beach or Pacific County for a Long Beach-area parcel, this is the process.
Closeout on the peninsula
Walk-through, punch list, keys, and warranty. The home should heat in January like a small house, not a seasonal cabin. That was the goal on the Long Beach job, where it replaced the RV.
Send the address and we’ll match a model to your Land Use District and your lot.
