Research by DoINeedAPermit Research Team · Updated May 2026
The Short Answer
Any attached deck requires a permit in Arlington, no exceptions. Even a small 8x12 deck needs plan review and inspections. Freestanding ground-level decks under 200 sq ft and 30 inches high can sometimes skip permitting, but attached decks cannot.
Arlington's Building Department enforces the 2021 International Building Code (IBC) with Washington State amendments, and treats ALL attached decks as a structural upgrade requiring Department review and inspection sign-off. Unlike some neighboring Snohomish County cities that allow small detached decks over-the-counter with a simple permit fee, Arlington requires ledger-attachment plans for every attached deck — meaning you must show the flashing detail, beam-to-post hardware, and footing schedule before construction starts. The Puget Sound climate zone (4C west of the Cascades) demands 12-inch frost footings to meet IRC R507.1.3, shallower than the 30-inch requirement east of the mountains but still a critical detail the inspector will verify in the hole before concrete pours. The Department's plan-review process typically takes 2 to 3 weeks; same-day approval is not available for attached decks. Pay particular attention to the ledger flashing requirement (IRC R507.9 and Washington amendments)—Arlington inspectors flag missing or non-compliant flashing details as a primary rejection reason, so submitting a detailed cross-section of the flashing, siding removal, and rim-board attachment is essential to avoid delays.

What happens if you skip the permit (and you needed one)

Arlington attached deck permits — the key details

Arlington requires a permit for any deck attached to the house, regardless of size or height. The City of Arlington Building Department administers the 2021 IBC with Washington State amendments. The core rule is straightforward: if the deck is bolted or bolted-and-flashed to the existing rim board, it is an attachment to the primary structure and triggers structural review under IBC Chapter 3 (Fire and Life Safety) and IRC R507 (Decks). This means you cannot avoid permitting by claiming the deck is 'small' or 'temporary.' The Department's online portal (available through the City of Arlington website) allows you to submit permit applications, but plan review is not instantaneous—expect 2 to 3 weeks for a complete set of drawings (site plan, deck framing plan, details, and ledger flashing cross-section) and another 1 to 2 weeks for the Department to issue any comments or request revisions. The permit fee is typically $275 to $450, depending on the deck's valuation (usually calculated as square footage × $25 to $50 per sq ft of deck area). Owner-builders are allowed to pull permits for owner-occupied homes under Washington State law, but you must be present at all inspections and sign the final Certificate of Occupancy form.

The most critical detail in Arlington is the ledger flashing requirement, which is the source of roughly 40 percent of permit rejections in the Puget Sound region. IRC R507.9 and the Washington State Amendments require that the ledger board be flashed with metal flashing that extends under the rim board and over the siding, with the flashing either sealed with caulk or bent to shed water away from the house frame. Many homeowners and even some contractors submit vague framing plans that show the ledger bolted to the rim but do not include a cross-section showing how water is managed at that critical joint. The Building Department will reject a plan that does not include a detailed drawing (at least at 1 inch = 1 foot scale) showing the flashing, how the siding is removed or wrapped, and how the flashing connects to the existing rim board or band board. If your house has vinyl siding, the flashing must be installed under the siding layer; if it has brick or stucco, the flashing typically terminates at a weep hole or is sealed with exterior caulk. Inspectors will perform a final walk-through specifically to verify that the flashing is installed per the approved plan before issuing the final sign-off. Cutting corners here—for example, using only caulk instead of metal flashing, or omitting the flashing altogether—is the fastest way to fail final inspection and incur additional fines.

Frost depth and footing design are the second most common rejection reason in Arlington. The Puget Sound climate zone (4C west of the Cascades) requires 12-inch frost-line footings under IRC R403.1 and Snohomish County amendments. This means the bottom of the footing hole must extend at least 12 inches below finished grade at the coldest point of the year. Arlington is west of the Cascades, so 12 inches is your threshold—not 30 inches, and not 18 inches. The City of Arlington does not have a soil-specific deeper requirement, so 12 inches is the minimum. However, if your lot is in a flood zone (check the FEMA Flood Insurance Rate Map via floodsmart.gov), the footings may need to be deeper to avoid flotation risk during high water; the Building Department will flag this during plan review. The permit application should include a footing schedule showing the hole depth, post size (typically 4x4 PT or 6x6), the type of footing (concrete pier, Sonotube, or frost-protected shallow foundation), and the bearing capacity of the soil. If you do not know your soil type, the Department will ask you to perform a soils test (usually $300–$600) or reference a geotechnical report from a previous project on the lot. Post footings in glacial till (common in Arlington) typically bear at 2,000 to 3,000 pounds per sq in., which is adequate for residential deck loading, but the plans must state the assumed bearing pressure.

Guardrails and stairs add complexity and cost but are required if the deck is over 30 inches above grade. IRC R311 and R312 govern both. Guardrails must be 36 inches high from the deck surface (42 inches in some jurisdictions, but Arlington adopts the standard 36-inch requirement) and must have infill spacing that does not allow a 4-inch sphere to pass through (to prevent child entrapment). Deck stairs must have treads of 7 to 11 inches deep, risers of 4 to 7.75 inches, and handrails 34 to 38 inches above the stair nosing if serving four or more risers. These dimensions are nearly universal, but they are also common rejection points because contractors sometimes estimate stair dimensions without calculating them precisely. The Building Department expects to see a stair layout drawing showing the total rise, number of risers, tread depth, and handrail location. If your deck will be higher than 30 inches, the stairs are a non-negotiable code requirement; if your deck is lower, stairs are optional. Many Arlington homeowners build 24-inch-high decks to avoid the stair requirement and thereby reduce cost and complexity.

The inspection sequence is: (1) footing pre-pour inspection, where the inspector verifies the hole depth, post size, and bearing soil; (2) framing inspection, which includes ledger flashing, rim board, joist attachment, beam-to-post connections (typically Simpson DTT lateral devices per IRC R507.9.2), and guardrail framing; and (3) final inspection, which re-checks the flashing, guardrail infill spacing, stair dimensions, and overall structural integrity. These inspections are free once the permit is pulled, and they are mandatory before you can use the deck. The typical timeline is permit submission on a Monday, plan review comments by Friday of the second week, revision submission by the following Monday, re-review and approval the following Friday, footing pre-pour inspection on the next available business day, framing and final inspections after completion. Total elapsed time from permit submission to final approval is usually 4 to 6 weeks if there are no resubmissions required. If the plans are incomplete or have multiple rejections, add 2 to 4 more weeks. Expedited review (5 business days) is available for an additional fee of $150 to $300, but the Department still requires complete, code-compliant plans to process the expedited request.

Three Arlington deck (attached to house) scenarios

Scenario A
12x16 attached deck, 24 inches above grade, no stairs or electrical, Puget Sound location (west Arlington)
You're building a modest attached deck on the back of your 1980s colonial in west Arlington, just off the kitchen slider. Dimensions are 12 feet wide by 16 feet deep (192 sq ft), and the deck surface will sit 24 inches above grade because your house has a crawlspace. Since the deck is attached and over 200 sq ft, a permit is required; since it's under 30 inches high, no stairs are needed, and no guardrail is required (IRC R312.1 exempts decks under 30 inches). The ledger board will attach to your vinyl-sided rim board, so the plans must show a cross-section with metal flashing installed under the siding and caulked or sealed at the top. You'll use four 4x4 posts set in concrete footings 12 inches deep (the Puget Sound frost line), and 2x8 joists on 16-inch centers with joist hangers. The Building Department will require a site plan showing the lot lines and deck location, a framing plan showing the joist layout and ledger detail, a footing schedule, and the ledger flashing cross-section. Expect the permit to cost $300 to $400 based on the valuation of 192 sq ft x $40/sq ft = $7,680 valuation. Plan review will take 2 to 3 weeks; footing pre-pour and framing inspections will occur after you've dug the holes and built the frame, and final inspection will occur after the guardrail is installed (even though it's optional, the Department will verify the flashing at final). Timeline: submit permit mid-January, get approval by early February, footing inspection by mid-February, framing inspection by late February, final inspection by early March. Total cost including permit, materials, and contractor labor: $6,000 to $10,000.
Permit required | Frost depth 12 inches (Puget Sound) | Ledger flashing with metal trim | 4x4 PT posts in concrete footings | Joist hangers required | No stairs or guardrails needed | Permit fee $300–$400 | Material and labor $5,500–$8,500 | Total project cost $5,800–$8,900
Scenario B
10x10 attached deck, 42 inches above grade, four risers with stairs, no electrical, Eastside Arlington (higher elevation, 30-inch frost depth)
You're building an elevated deck on the east side of Arlington (upland toward the Cascade foothills) where your house sits on a steep slope. The deck will be 10x10 feet (100 sq ft) but 42 inches above grade due to the hillside, so it requires both a permit and a full stair plan because the height exceeds 30 inches. The footing requirement is different here: instead of the Puget Sound 12-inch frost depth, Arlington's eastside falls into a zone with deeper frost (approximately 30 inches) per the climatic data tables. You must show 30-inch footing depth in the plans to get approval; the Building Department will reference the local soil maps and may ask for a soils test if the lot has a history of unstable soil or is near a stream. The stairs will be a four-riser configuration with 7-inch treads and 7-inch risers (total rise of 28 inches, plus the deck surface, equals 42 inches of total elevation). The Building Department will require detailed stair calculations showing the riser and tread dimensions, a handrail layout, and an infill specification (either balusters at 4 inches on center or solid screening). Since the deck is elevated and the stairs are a key part of the structure, the inspector will perform two inspections: footing pre-pour (verifying the 30-inch depth and soil conditions) and a combined framing and stairs inspection (checking the stair stringers, handrail attachment, and guardrail infill). The ledger flashing plan is the same as Scenario A: metal flashing under the siding with caulk or sealant. Permit cost is $325 to $450 based on valuation; the stairs add complexity and usually trigger a longer plan review (3 to 4 weeks instead of 2). Total timeline: 5 to 7 weeks from submission to final approval. Material and labor cost is higher due to the stairs and deeper footings: $7,000 to $12,000. This scenario showcases the difference between Puget Sound and eastside frost-depth requirements; a 12-inch footing designed for west Arlington will fail inspection on the eastside and must be redesigned.
Permit required | Frost depth 30 inches (eastside/upland) | Ledger flashing required | 4x4 PT posts in concrete footings, 30 inches deep | Four-riser staircase with handrails | Guardrail infill 4 inches or less | Stair plan required | Permit fee $325–$450 | Material and labor $6,500–$11,000 | Total project cost $6,825–$11,450
Scenario C
16x20 attached deck with built-in benches, 24 inches above grade, ground-level patio section underneath (freestanding), no electrical, mixed structure
You're building a larger deck with a two-part design: a 16x20 elevated section (320 sq ft) attached to the house at 24 inches above grade, plus a 12x16 ground-level patio (192 sq ft) that is freestanding and directly adjacent. The freestanding patio section does not require a permit if it is under 200 sq ft and under 30 inches high (IRC R105.2 exemption). However, the 16x20 attached section DOES require a permit because it exceeds 200 sq ft and is structurally attached. Many homeowners mistakenly think they can combine these two sections into a single project and claim the whole thing as freestanding, but the Arlington Building Department will see the attached portion as the trigger and require permit review for the entire design. The plans must clearly show which portion is attached (with ledger flashing and joist hangers) and which portion is freestanding (with independent footings, no attachment to the house). The attached section uses standard 12-inch frost footings; the freestanding patio can also use 12-inch footings if it is west of the Cascades (Puget Sound zone). Built-in benches that are structural (attached to the deck frame or providing lateral support) may be required to be shown in the plan; movable benches do not. The permit fee is calculated on the valuation of the 320 sq ft attached section (approximately $12,800 valuation at $40/sq ft), resulting in a permit fee of $350 to $500. Plan review takes 2 to 3 weeks because the Department must verify that the attached and freestanding sections do not inadvertently create a composite structure that is larger than intended. Inspections are footing pre-pour, framing (attached section and any structural benches), and final (ledger flashing, guardrail infill, and overall safety). This scenario showcases the Arlington Department's attention to composite structures and their requirement to clearly delineate attached versus freestanding components; mixing the two in a single design is a common source of plan rejections and re-submissions.
Permit required for attached 16x20 section (320 sq ft) | Freestanding patio section exempt if under 200 sq ft and 30 inches | Ledger flashing for attached portion | 4x4 PT posts in 12-inch frost footings | Structural benches must be shown in plans | Permit fee $350–$500 | Material and labor $8,000–$14,000 | Total project cost $8,350–$14,500

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Ledger flashing and water management: why Arlington inspectors are meticulous

The Puget Sound region receives 35 to 40 inches of rain per year, concentrated in fall and winter. Water infiltration at the ledger board—the point where the deck attaches to the house—is the number-one cause of deck failure and house-frame rot in this climate. IRC R507.9 mandates metal flashing that directs water away from the rim board and existing house framing. Arlington's Building Department has seen dozens of failed decks where the flashing was omitted, installed backward, or sealed with caulk only (which cracks and fails within 3 to 5 years). The Department's inspection protocol is to verify the flashing is installed per the approved plans before issuing final sign-off, and inspectors will request photographic evidence or perform a physical inspection of the ledger area.

The critical detail is that the flashing must be installed UNDER the siding layer if the house has vinyl siding (the most common case in Arlington), or at a weep hole if the house has brick or stucco. If your contractor installs the flashing on TOP of the siding, water will run behind the siding and rot the rim board. The Building Department's plan-review team will flag this error during the 2-week review period and request a revised drawing. Many contractors are familiar with this requirement in older regions (like New England) but are careless in the Pacific Northwest, where the code enforcement is stricter due to the wet climate. To avoid delays, submit a detailed cross-section drawing at a scale of at least 1.5 inches = 1 foot, showing the siding, flashing, rim board, ledger board, bolts, and any gaps or sealants. Label the flashing type (e.g., 26-gauge galvanized steel, Z-flashing, or membrane flashing), the siding removal depth, and the bolt spacing (typically 16 inches on center). This single drawing will prevent most plan-review rejections and accelerate approval.

After final inspection, homeowners should plan to maintain the flashing annually. Debris accumulation, moss growth, and caulk degradation are all common in the rainy climate and can compromise the flashing's effectiveness. Inspect the ledger area in spring and fall, clear any debris, and re-caulk any visible gaps with exterior-grade silicone caulk. This maintenance step is not a code requirement, but it will extend the life of the deck and prevent the rot issues that have sidelined many Arlington decks built 15 to 20 years ago.

East versus west Arlington frost-depth requirements and footing design

Arlington straddles the divide between two climate zones: 4C (Puget Sound maritime, 12-inch frost depth) west of the Cascades and 5B (drier upland, 30-inch frost depth) east of the Cascades. This means the frost-line requirement for your deck footings can DOUBLE depending on which side of town your house is on. The Building Department uses county assessor parcel maps and the NOAA climatic data tables to determine which zone applies to each lot. If your address is west of Stanwood or north of Arlington proper (closer to Puget Sound), the 12-inch frost depth applies. If your address is east toward the foothills or in the upland neighborhoods, 30-inch footings are required. Many Arlington permit applicants are unaware of this division and submit plans with 12-inch footings for an eastside lot, only to have the Department reject the plans and require resubmission with 30-inch footings.

The financial and logistical impact is significant. A 12-inch footing hole in glacial till (the common soil type in Arlington) takes one worker with a shovel or auger 30 minutes to 1 hour per post. A 30-inch hole can take 2 to 3 hours per post, especially if the auger hits rock or clay layers. For a four-post deck, the difference is 2 to 8 additional labor hours. In concrete, the difference is modest (an extra 18 inches of concrete depth per hole, or roughly 0.5 cubic feet per hole), but the excavation labor and equipment rental (if you hire a contractor) can add $400 to $800 to the project cost. To avoid this costly revision cycle, verify your exact frost-depth requirement BEFORE you submit your permit application. Call the City of Arlington Building Department or check the online permit portal's FAQ section; many jurisdictions have a frost-depth tool or map that pinpoints your requirement based on your address.

Soil conditions also matter. Arlington's soils vary widely from glacial till (dense, competent, bearing capacity 2,000 to 3,000 psf) to alluvial silt and clay (softer, bearing capacity 1,000 to 1,500 psf) depending on the neighborhood and proximity to the Snohomish River. The permit plans must state the assumed bearing pressure for the footings. If you don't have a soils test or geotechnical report, the Department will accept a generic assumption of 2,000 psf if the lot is not in a flood zone or on a known unstable slope. If the Department suspects poor soil or if your lot is in a flood zone, they will request a soils investigation (usually $300 to $600 for a simple boring and lab test) before approving the footing design. Plan for this possibility in your schedule; a soils test can add 1 to 2 weeks to the approval timeline.

City of Arlington Building Department
Arlington City Hall, 210 Olive Street, Arlington, WA 98223
Phone: (360) 403-3300 | https://www.arlingtonwa.gov/government/permits
Monday–Friday, 8:00 AM–5:00 PM (closed holidays; verify locally)

Common questions

Can I build an attached deck without a permit in Arlington?

No. The City of Arlington requires a permit for every attached deck, regardless of size or height. The ledger attachment to the rim board triggers the permit requirement under the 2021 IBC. Freestanding ground-level decks under 200 sq ft and 30 inches above grade may be exempt, but once the deck is attached to the house, a permit is mandatory. Unpermitted attached decks discovered during a property inspection or sale can result in stop-work orders, fines of $500–$1,500, and forced removal.

How much does a deck permit cost in Arlington, Washington?

Permit fees in Arlington range from $275 to $500, typically calculated as 1.5% to 2% of the deck's valuation. For example, a 12x16 deck (192 sq ft) valued at roughly $7,680 (192 sq ft × $40/sq ft) would incur a permit fee of about $300–$400. Larger decks (16x20 or bigger) cost $400–$500. Expedited review (5 business days instead of 2–3 weeks) adds $150–$300 to the permit fee.

What is the frost depth requirement for deck footings in Arlington?

Frost depth depends on your location within Arlington. West of the Cascades (Puget Sound zone 4C), frost depth is 12 inches. East of the foothills (zone 5B), frost depth is 30 inches. Confirm your zone by calling the Building Department or checking your lot's climatic zone on the county assessor map. Submitting a footing plan with the wrong frost depth is a common rejection reason and will delay your permit approval by 2 to 4 weeks.

Do I need stairs on my Arlington deck?

Stairs are required only if the deck is more than 30 inches above grade (IRC R311.7). If your deck is 24 inches or lower, stairs are optional. If you build stairs, they must have treads 7–11 inches deep, risers 4–7.75 inches high, and handrails 34–38 inches above the stair nosing if there are four or more risers. The Building Department will require a detailed stair layout drawing showing these dimensions before approving your permit.

What is the most common reason deck permits are rejected in Arlington?

The most common rejection is an incomplete or missing ledger flashing detail. IRC R507.9 and Washington State amendments require metal flashing that directs water away from the house frame. Many applicants submit a framing plan without a detailed cross-section showing how the flashing is installed, where it connects to the rim board, and how water is shed. Submit a 1.5-inch-to-1-foot scale cross-section drawing showing the flashing, siding removal, ledger board, rim board, bolts, and caulk or sealant. This single drawing prevents most rejections.

How long does the permit approval process take in Arlington?

Standard plan review takes 2 to 3 weeks for a complete, code-compliant set of drawings. If the Department has comments or requests revisions, add another 1 to 2 weeks for resubmission and re-review. Once approved, footing pre-pour, framing, and final inspections occur after construction begins, typically within 2 to 4 weeks. Total elapsed time from submission to final approval is usually 4 to 6 weeks. Expedited review is available for an additional $150–$300 fee and reduces the review time to 5 business days, but complete plans are still required.

Do I need an HOA approval in addition to a building permit for my Arlington deck?

If your home is in an HOA community, the HOA may have its own design and approval process separate from the city permit. Check your CC&Rs (Conditions, Covenants, and Restrictions) or contact your HOA board to see if architectural review is required. HOA approval and city permits are independent processes; you need both. Allow 2 to 4 additional weeks for HOA review if required.

Can I pull a deck permit as an owner-builder in Arlington?

Yes. Washington State law allows owner-builders to pull permits for owner-occupied homes. You must be present at all inspections and sign the final Certificate of Occupancy. However, the City of Arlington still requires complete, code-compliant plans; you cannot bypass plan review or inspections. Many homeowners hire a designer or contractor to prepare the plans and then pull the permit in their own name to save the contractor's overhead costs.

What happens if my deck collapses and it was built without a permit?

If someone is injured in a collapse and your homeowner's insurance investigates the cause, they will discover the unpermitted status and may deny your claim entirely (typically $100,000+ in medical or liability coverage). Additionally, if a property inspector or buyer's lender discovers the unpermitted deck during a transaction, the lender will require a permit and final inspection sign-off or refuse to close on the mortgage. Forced removal of the deck may also be ordered by the Building Department if it is found to be non-compliant with code, at your cost ($3,000–$8,000 for a typical deck).

Are there any exemptions for small decks in Arlington?

Freestanding ground-level decks under 200 sq ft and under 30 inches above grade may be exempt under IRC R105.2, but this exemption does NOT apply to attached decks. Once a deck is ledger-bolted or flashed to the house, it is an attachment and requires a permit, even if it is small. If you are considering a freestanding patio beside your house, verify with the Building Department that the structure truly has no attachment and will qualify for the exemption before proceeding without a permit.

Disclaimer: This guide is based on research conducted in May 2026 using publicly available sources. Always verify current deck (attached to house) permit requirements with the City of Arlington Building Department before starting your project.