Deck Footings in Seattle: Why Standard Concrete Piers Often Fail in King County Soil

If you've ever watched a Seattle deck start to lean after its first few winters, you've seen what happens when a builder underestimates what's under the ground. Footings are the least glamorous part of any deck project — they're buried, invisible once the build is finished, and rarely mentioned in the photos homeowners share on Instagram. But in King County, they are unquestionably the most consequential structural decision you'll make. Get them right and your deck stands level for 30 years. Get them wrong and you're looking at cracked concrete, shifting posts, failed ledger connections, and a permit problem you didn't see coming.

The reason footings are so critical here is Seattle's geology. The ground beneath most King County lots is a legacy of the last ice age — thousands of feet of glacially deposited material compressed into a patchwork of glacial till, clay lenses, outwash sands, and perched water tables that behave unpredictably under load. Unlike the sandy loam you'd build on in Phoenix or the stable subsoil beneath a flat Midwest lot, our soils expand when saturated, compress when they dry, and can move laterally on a slope in ways that standard concrete tube piers simply aren't designed to resist. Washington State's frost line sits between 12 and 18 inches in western Washington — modest compared to Minnesota's 42 inches — but when you combine even shallow frost heave with waterlogged clay, the forces acting on an undersized footing are substantial.

This guide covers what every Seattle homeowner should understand before a single shovel goes in the ground: soil types across King County, footing depth minimums for unincorporated county versus City of Seattle lots, why standard Sonotube tube piers fail in the wrong conditions, when helical piers are the right answer, what inspectors look for before you pour, and the true installed costs so you can evaluate any contractor's bid with confidence.

Seattle's Glacial Geology: Why Your Soil Type Determines Your Footing

Most of King County sits on material deposited during the Vashon Glaciation, which ended roughly 14,000 years ago. When the Puget Lobe of the Cordilleran Ice Sheet retreated, it left behind two fundamentally different soil types that now exist side by side across the region — sometimes within the same lot.

Glacial Till: Dense, Clay-Heavy, and Poorly Drained

Glacial till is the overcompacted mix of clay, silt, sand, and gravel that was ground beneath the glacier itself. In many parts of Seattle — Beacon Hill, First Hill, the West Seattle uplands, much of Bellevue's hillside neighborhoods, and most of south King County — till is the dominant surface material. It's dense enough that it can have reasonable bearing capacity when dry, often 2,000–3,000 pounds per square foot (psf). The problem is that till is dominated by clay particles that hold water. When saturated — which in the PNW happens from October through April without interruption — clay swells. When it dries in summer, it shrinks. This seasonal expansion and contraction is called shrink-swell behavior, and it's exactly what causes a tube pier to slowly migrate upward over the course of several winters.

The permeability of glacial till is extremely low — often less than 0.001 inches per hour. Rain that falls on a clay till surface can't percolate downward quickly enough to drain before the next storm arrives. This creates a perched water table — a saturated zone sitting above the true water table — that can exist within the top two feet of soil even on a hillside lot with excellent surface drainage. If your footing bottom sits in or near this saturated zone, the concrete is surrounded by soil that behaves more like a sponge than a structural base.

Glacial Outwash: Drains Well, But Watch for Loose Layers

Glacial outwash is the sandy, gravelly material deposited by meltwater streams running ahead of or beneath the glacier. You find it in the lower-elevation flats — the Duwamish River valley, the Kent Valley, parts of Renton, Auburn, Federal Way, and the lowland areas of Kirkland and Redmond near the lake. Outwash drains quickly (sometimes too quickly, making irrigation a challenge in summer) and generally provides good bearing capacity when it's compacted. A footing in well-graded outwash gravel can achieve 2,500–4,000 psf bearing, which is excellent for residential deck loads.

The catch with outwash is loose stratification. Not all outwash is uniform — glacial streams deposited material in layers, and some layers are fine-grained silts with low bearing capacity. A contractor boring a footing hole in what looks like solid gravel can punch through into a soft silt layer two feet down. Without a soil probe or engineer review, this goes undetected until the footing settles.

How to Tell What You Have

If you're in unincorporated King County, King County's GIS portal has soil survey data that gives a general indication. For city lots, the Seattle SDCI publishes critical areas maps showing steep slopes and known geologically hazardous areas where engineered footing plans are mandatory. But the most reliable method is to simply dig a test hole 24 inches deep and look: clay till is dense, grayish-brown, and sticky when wet. Outwash is grainy and crumbles apart. If your hole fills with standing water within an hour of digging, you have a perched water table and you need to tell your contractor before footings are spec'd.

Frost Line Depth in King County: What the Code Says vs. What the Soil Demands

Washington State's residential building code (currently the 2021 Washington State Residential Code, based on the IRC) sets the frost depth for western Washington — including all of King, Pierce, Snohomish, and Kitsap counties — at 12 inches. That's the code floor. Exterior footings must extend a minimum of 12 inches below undisturbed grade.

Why 12 Inches Is a Starting Point, Not an Endpoint

Twelve inches gets you below the literal frost line for the Puget Sound lowlands — we rarely see ground frost penetrate deeper than 6–8 inches even during the cold snaps that hit in January. But in clay soils, frost heave is only one of two failure mechanisms. The bigger problem is bearing capacity and the active zone.

The "active zone" is the upper layer of soil that undergoes seasonal moisture change — swelling when saturated and contracting when dry. In Seattle's clay till, this zone typically extends 18–24 inches below grade. A footing with its base sitting inside the active zone is subject to the full upward force of clay expansion every wet season. Even if frost never penetrates that deep, waterlogged clay generates significant vertical pressure.

This is why most experienced King County deck builders set tube footing depths at 18–24 inches minimum, even though the code only requires 12. The extra depth moves the footing base below the active zone into more stable, less moisture-variable soil. On hillside lots with suspect soils, depths of 30–36 inches are common before hitting competent material.

Frost Line Depth Variation Across King County Zip Codes

While the official frost line is uniform at 12 inches for western Washington, soil behavior varies enough by location that effective footing depth recommendations differ across the county:

These are practical working guidelines based on regional soil patterns, not official code tables. Your specific lot may vary — especially if you have any indication of historic fill, landslide history, or a high seasonal water table.

Why Tube Piers (Sonotubes) Fail in Seattle Clay

The standard Sonotube — a cardboard tube form typically 10, 12, or 16 inches in diameter, filled with concrete poured in a hand-dug hole — is the default footing method for residential decks across North America. It works perfectly well in stable, well-drained soils. In Seattle's clay, it's often the wrong tool.

The Frost Heave Mechanism in Clay

Here's the physics of what happens. A Sonotube pier has a smooth cylindrical surface. When the surrounding clay soil becomes saturated and then slightly cools — not even to the point of frost, just to the point of increased soil pressure from swelling — it exerts upward pressure on the sides of the cylinder through a mechanism called adfreeze or soil friction. The clay literally grabs the sides of the concrete cylinder and lifts it.

A standard 12-inch diameter tube pier has substantial surface area in contact with the surrounding soil. Over the course of a Seattle winter, that contact surface accumulates upward pressure. If the footing is shallow — sitting in the active zone — and the pier isn't belled at the bottom to provide a mechanical anchor against upward movement, the pier will migrate upward. One winter might be 1/8 inch. Over five winters it's a visible lean, a post base that's lifted off its anchor, and framing connections that are now stressed in ways the engineer never intended.

Poor Bearing Capacity in Saturated Clay

Beyond frost heave, saturated clay simply doesn't hold load well. A clay soil that tests at 2,000 psf when firm may drop to 1,000 psf or less when fully saturated. A typical 12-inch Sonotube has a base area of 0.785 square feet. At 1,000 psf saturated bearing capacity, you're working with about 785 pounds of allowable load per footing. A loaded deck corner post can easily carry 1,500–3,000 pounds of load in a large deck. You can see the arithmetic problem.

The solution is either a larger diameter footing (16-inch piers are significantly better) or a belled footing that expands the base area below the active zone. Some contractors use tube piers with a separate flared base form — these work well if the bell is placed below the active zone in competent soil.

When Tube Piers Are Acceptable in King County

Tube piers remain the right call in a clear set of conditions:

• Outwash soils with good drainage and documented bearing capacity above 2,000 psf at footing depth
• Flat lots without slope stability concerns
• Deck loads are modest (smaller deck, single story, no hot tub)
• Footing depth is at least 18 inches on outwash, 24 inches minimum on any clay-dominant lot
• The footing diameter is 12 inches minimum, 16 inches preferred for corner posts

For elevated decks or decks with hot tubs where point loads are higher, go larger or go helical.

Helical Piers: The Engineered Solution for Difficult Seattle Soils

Helical piers — steel shafts with one or more helical plates welded at intervals — are the gold standard for deck footings in problematic soil conditions. They're installed by rotating the shaft into the ground with hydraulic torque equipment, advancing until they reach target torque (which corresponds to a specified bearing capacity), not just a target depth. That distinction is critical: a helical pier doesn't stop at 18 inches because 18 inches is "deep enough." It stops when the soil says it's ready.

How Helical Piers Work in Clay

The helical plates on the pier shaft act like a giant screw thread. As the shaft is rotated into the ground, the plates advance downward — not displacing soil sideways (as an auger does) but cutting through it along the helix path. Once at target depth (determined by torque readings, not just tape measure), the plates provide both compressive bearing and tension resistance. In uplift-prone clay soils, the helix acts as a mechanical anchor that resists the upward pull of frost heave and soil expansion. The smooth round shaft above the helix point presents minimal surface area for adfreeze adhesion.

For Seattle clay, helical pier installers typically use 2.875-inch or 3.5-inch diameter shafts with 8-inch or 10-inch helix plates. Larger helix diameters are used in softer soils where you need more bearing area. Multiple helix sections can be added if the target torque isn't achieved at the first plate depth.

Companies like Techno Metal Post of Seattle and GoliathTech install helical piers across King County with certified torque monitoring and provide installation records — important documentation for permit files and for future buyers.

When Helical Piers Are the Right Call

• Hillside lots with any slope concern: Lateral loads on a deck post on a 15% slope can exceed what a concrete footing's embedment can resist without engineered anchor capacity.
• Perched water table within 24 inches: If your footing hole fills with water before you pour, standard concrete placement is compromised. Helical piers eliminate the problem.
• Confirmed soft clay or fill below 18 inches: If you can't find competent bearing at reasonable depth, helical piers reach past the soft zone.
• Hot tub decks: The point load from a filled hot tub can exceed 2,000 pounds per post. Helical piers sized for this load give engineered documentation.
• Steep slope lots in Seattle or unincorporated King County: SDCI and King County permitting may require engineered pier design on slopes exceeding 15%.

Helical Pier Costs in King County

Installed cost per pier in King County ranges from $500 to $1,500, with most residential deck applications falling in the $700–$1,000 range per pier. A typical 16x20-foot deck might use 6–8 piers, putting total helical footing cost between $4,200 and $8,000. That's $3,000–$6,000 more than standard tube piers, but the difference disappears quickly when you factor in that helical piers essentially never need replacement or releveling in residential applications.

Concrete Tube Form (Sonotube) Requirements: Doing It Right When Tubes Are Appropriate

When site conditions support the use of tube piers, there are still right ways and wrong ways to execute them. The single biggest mistake we see on DIY or low-bid deck projects is an undersized, too-shallow tube pier with no hardware at the top.

Diameter and Depth Minimums

Washington State code doesn't specify footing diameter — it specifies that the footing must be capable of carrying the design loads with the soil's bearing capacity. This means you have to do the math. For a residential deck, the calculation looks like this:

Required footing area = Design load (lbs) ÷ Allowable soil bearing pressure (psf)

If a corner post carries 2,400 pounds and your soil has 1,500 psf allowable bearing:

2,400 ÷ 1,500 = 1.6 square feet required base area

A 16-inch diameter tube has a base area of 1.4 square feet. Close but not quite. A 18-inch diameter tube gives you 1.77 square feet — adequate with a small safety margin. This is why 16-inch minimum diameter is standard practice for corner and high-load posts, with 12-inch tubes used only for mid-span secondary posts with lower tributary load.

Depth minimums as a practical guide:

• Flat outwash lots with confirmed good bearing: 18 inches minimum
• Clay till lots: 24 inches minimum
• Any lot with observable wet season drainage issues: 24–30 inches
• Slopes greater than 10%: Consult engineer; typically 30–36 inches or helical

Concrete Mix and Placement

Footing concrete should achieve a minimum compressive strength of 3,000 psi (f'c = 3,000 psi), though 3,500 psi is preferred in our climate. Pre-mixed bag concrete from a home improvement store works for small jobs; for six or more piers, a ready-mix delivery is worth the minimum charge. The mix must not be soupy — overly wet concrete is weaker concrete. If it's raining during your pour, protect the pour from direct rain dilution.

Never pour concrete into a hole with standing water at the bottom. Either pump the water out immediately before the pour, or if water continually infiltrates, switch to helical piers. Water at the bottom of the hole weakens the concrete-soil interface and can result in a pier that's structurally adequate on paper but compromised in practice.

Tube Form Removal vs. Leaving In

Cardboard Sonotube forms must be removed after the concrete cures — cardboard rots and provides no structural contribution, and leaving it in place creates a void pathway for water. Some contractors use fiberglass tube forms that can remain in place, but these are more expensive. Standard cardboard tubes: strip after 24–48 hours of cure time, before backfilling.

Hillside Lot Considerations: Lateral Load, Embedment, and Engineer Requirements

Seattle's most dramatic lots — the hillsides of Queen Anne, the ravine edges of Maple Leaf, the slopes of Mercer Island, the steep grades behind homes in Issaquah Highlands — present footing challenges that go well beyond what depth and diameter can solve. On a slope, footings must resist not just the vertical load of the deck and occupants but lateral load: the horizontal force generated by soil pressure, wind, and the geometry of an elevated deck cantilevering away from the hillside.

What Lateral Load Means for Your Footings

On flat ground, a post footing primarily resists compression — it's being pushed straight down by the weight above it. On a hillside, the downslope post is being pushed down and sideways simultaneously. The soil behind the footing pushes inward and downward; wind load pushes the entire deck laterally. Standard tube piers aren't designed to resist significant lateral (horizontal) force. They resist it only through friction with the surrounding soil and the passive pressure of soil against the footing side. In loose or saturated clay, that passive pressure is much lower than in firm, stable soil.

Lateral resistance requires either:

1. Deep embedment — the footing extends far enough below grade that the soil's passive resistance against the embedded section is adequate. This typically means 36 inches or more in soft soils.
2. Engineered helical piers designed for combined vertical and lateral load.
3. A grade beam connecting multiple footings, distributing lateral load across a wider base.

For decks on lots with slopes greater than 15%, most King County inspectors will require a stamped engineer's plan before approving footing design. This is not negotiable, and it's not the contractor trying to upsell you — it's code-required engineering that protects both your structure and the hillside below it.

Landslide Hazard Areas in Seattle

The Seattle SDCI maintains critical areas maps that designate Landslide Hazard Areas, Steep Slope Hazard Areas, and Seismic Hazard Areas. If your lot falls in any of these designations, additional soils investigation is typically required before permits are issued. A geotechnical report from a licensed soils engineer will specify footing design recommendations — type, depth, diameter, and any special drainage requirements around footings.

This isn't just bureaucratic overhead. Seattle's Landslide Hazard designations exist because we have a documented history of slope failures on our clay-dominated hillsides. The 2001 Nisqually earthquake triggered numerous landslides across King County. A deck with improperly designed footings on a slope doesn't just risk the deck — it can contribute to slope instability.

Embedment Depth on Slopes

For hillside lots, embedment depth is measured differently than on flat ground. You're looking at the vertical distance from the downslope grade to the footing base — not just the depth below the upslope grade. A footing that's 24 inches below the upslope grade but only 12 inches below the downslope grade on a steep lot is effectively a 12-inch deep footing from a lateral resistance standpoint. This is why hillside footing depths are often specified as "24 inches below downslope grade" or "to bedrock/competent material," whichever is deeper.

Permit Inspection, Drainage, and Post Base Hardware

The Footing Inspection: Non-Negotiable in King County

Both Seattle SDCI and King County Permitting require a footing inspection before concrete is poured. This inspection is not optional — it's a condition of your building permit. The inspector will verify:

• Footing hole depth (they measure)
• Footing hole diameter
• Location relative to approved site plan
• Soil conditions at the base (no standing water, no loose disturbed material)
• Any required rebar placement

You must call for inspection and get a pass before any concrete goes in the ground. In King County, you schedule inspections through King County's permit portal. In Seattle, you use the SDCI scheduling system. Same-day inspections are rarely available — plan for 24–48 hours minimum.

If you pour without inspection, the inspector can require you to core or excavate the footing to verify it meets code. In practice, many inspectors will require you to expose the footing or demonstrate compliance some other way. This is expensive and avoidable.

Drainage Around Footings

One of the most overlooked footing details on Seattle decks is what happens to the water that runs off the deck surface, the house, and the surrounding grade. Clay soil doesn't absorb water fast enough to drain freely, so water ponds near footings. Ponding water around a footing in clay soil accelerates the frost heave and shrink-swell cycles that damage piers.

Best practice for King County footings:

• Grade the soil away from all footings (minimum 2% slope away from the pier)
• In high-drainage-concentration areas, install a gravel collar (6-inch radius of clean crushed rock) around each footing base before backfilling with native soil
• Don't let deck downspouts or roof drainage discharge near footings
• If the deck is elevated with water collecting underneath, consider a below-deck drainage system that channels water to a defined discharge point away from footings

For membrane decking or waterproof deck systems, drainage planning is part of the structural design — not an afterthought.

Simpson Strong-Tie Post Base Hardware

Post base hardware serves two purposes on a Seattle deck: it creates the mechanical connection between the post and footing (required by code for shear and uplift resistance), and it holds the wood post end above the concrete surface, preventing direct wood-to-concrete moisture contact that accelerates rot.

The Simpson Strong-Tie product line is the industry standard in our region. For exterior deck applications in the PNW climate, you need ZMAX galvanized or stainless steel hardware — standard G90 galvanization corrodes too quickly in our wet environment.

Common post base specs for King County decks:

Hardware is installed with the recommended Simpson Strong-Tie screws or LedgerLOK fasteners — not standard wood screws, which are not rated for the shear loads connector hardware is designed to transfer.

Bearing Capacity Calculations and What They Mean for Your Deck Design

Bearing capacity is the soil's ability to support a compressive load without excessive settlement. It's expressed in pounds per square foot (psf). Knowing your site's bearing capacity is how you size your footings — not by guessing or using "standard" dimensions across the board.

Typical Bearing Capacities for King County Soils

The American Wood Council and the International Building Code both provide presumptive bearing values for common soil types. These are the values permit-drawing engineers use when a full geotechnical investigation isn't required:

The key takeaway: the difference between summer and winter bearing capacity in King County clay can be 2:1 or worse. Engineers who design decks for year-round use in the PNW are supposed to use the saturated condition, not the favorable summer value.

Working Through a Simple Calculation

Say you're building a 16x24-foot deck (384 square feet). Standard deck live load is 40 psf plus 10 psf dead load = 50 psf total. Total load = 384 × 50 = 19,200 pounds. You have 8 footings. Load per footing = 2,400 pounds average (corner posts carry slightly more than center posts).

Your soil is stiff clay till in wet condition: 1,500 psf allowable bearing (using a safety factor applied to the presumptive 2,000 psf).

Required footing area = 2,400 ÷ 1,500 = 1.6 sq ft

Diameter needed: sqrt(1.6 ÷ 0.785) × 12 = 17.6 inches → use 18-inch diameter minimum.

If you add a 450-gallon hot tub (roughly 4,200 pounds filled plus tub weight), the two posts supporting it carry 3,000–4,000 pounds each. Now you need 2.7 sq ft of base area — a 22-inch diameter pier or a helical pier.

When an Engineer Is Required

Seattle SDCI and King County Permitting generally require a stamped engineer's plan for:

• Decks on lots with slopes greater than 15%
• Decks in designated Landslide Hazard Areas
• Decks with hot tubs or concentrated loads above code minimums
• Any structure where the standard prescriptive code path can't be followed
• Second-story decks or decks attached to structures with unusual framing

Outside these triggers, most residential decks can be permitted with standard plan sets that don't require an engineer stamp, as long as they follow the IRC prescriptive design path. But if your site has any of the soil or slope conditions described above, voluntarily engaging a structural engineer for footing design is money well spent. Engineering fees for footing design run $500–$1,500 for a typical residential deck — a small fraction of the cost of a footing failure.

Cost Breakdown: What to Budget for Footings in King County

Footing costs are one of the most variable line items in a Seattle deck build because they depend heavily on what's underground. A responsible contractor will give you a base price with a clear description of what assumptions were made, and a change order process for conditions discovered during excavation.

Per-Pier Cost Breakdown

Standard 12-inch Sonotube, 18-inch depth, flat lot:

• Excavation (hand or small auger): $25–$50
• Sonotube form and concrete: $40–$80
• Post base hardware (Simpson ABU/PBS): $25–$45
• Labor: $60–$100
• Total per pier: $150–$275 installed

16-inch Sonotube, 24-inch depth, clay soil:

• Excavation (may need power auger): $50–$80
• Sonotube form and concrete: $70–$120
• Post base hardware: $35–$55
• Labor: $80–$120
• Total per pier: $235–$375 installed

Helical pier, flat-to-moderate slope:

• Equipment mobilization (amortized per pier): $75–$150
• Helical pier shaft and helix plates: $150–$300
• Installation labor (hydraulic torque equipment): $200–$400
• Post base adapter cap: $50–$100
• Total per pier: $475–$950 installed

Helical pier, steep hillside with engineer review:

• Engineering: $150–$250 per pier (amortized)
• Equipment mobilization: $150–$250 per pier
• Heavy-duty shaft and multi-helix plates: $300–$600
• Installation labor: $400–$600
• Total per pier: $1,000–$1,500+ installed

What Drives Cost Higher

On clay lots, if the power auger hits a large cobble or boulder (common in glacial till), the crew has to switch to hand tools or move the footing location slightly — both cost time. Hillside lots with limited equipment access may require hand-digging or a smaller compact auger unit, which is slower. If groundwater infiltration requires pumping before each pour, that adds mobilization time. Budget a contingency of 15–20% on any footing work in King County.

If you're comparing bids for your deck project, reading the deck quote carefully will show you whether a contractor has specified footing type, depth, and diameter explicitly — or left it vague. Vague footing specs are a red flag.

Hiring a Contractor Who Understands Seattle Soil

Not every deck contractor in the Puget Sound market has deep experience with footing design in difficult King County soils. Some are experienced finish carpenters who've learned framing, and footings aren't their specialty. When you're vetting contractors for a project with any soil complexity, ask direct questions about footing approach before signing anything.

The questions that reveal a contractor's footing knowledge:

• "What footing depth and diameter do you spec for this soil type?" (They should ask about your soil first.)
• "How do you determine if soil conditions require helical piers instead of tube piers?"
• "Do you perform footing inspections before the pour, and how do you handle delays if the inspector can't come same-day?"
• "What post base hardware do you use, and is it rated for our wind exposure category?"
• "Have you built decks on lots similar to mine — same slope, similar soil?"

Our guide to vetting deck contractors in Seattle covers the full list of questions that separate experienced local builders from out-of-area operators who are unfamiliar with PNW soil conditions.

Any contractor working in Washington State on permitted work must be licensed through Washington State L&I. You can verify a contractor's license, bond, and insurance status using the L&I contractor lookup tool. This matters for structural work especially — if a footing fails and the contractor isn't properly licensed, your legal and insurance recourse is significantly reduced.

The relationship between footings, permits, and long-term value is real. Buyers' agents increasingly ask about permit history on Seattle decks, and an unpermitted or uninspected deck is a negotiation liability at resale. Our King County permit guide walks through the full permitting timeline from plan submittal to final inspection.

For homeowners thinking about the full project investment, Seattle deck costs in 2025 covers how footing upgrades (helical vs. tube) affect the total project budget and what you can expect per square foot across different site conditions.

Closing: Get the Foundation Right Before You Think About the Decking

The composite decking, the cable railing, the under-deck drainage system — all of that is visible and satisfying to design. But every bit of it rests on whatever's happening six inches below grade. In Seattle's glacial clay, that invisible foundation deserves more attention than it typically gets.

The cost difference between a properly spec'd footing system and a marginal one on a typical King County deck is $1,500 to $4,000 depending on site conditions. Over a 30-year deck lifespan, that's an insurance policy that costs less than a single year's worth of property taxes. The cost of a footing failure — structural remediation, permit work after the fact, post base replacement, potential deck releveling — runs $8,000 to $25,000 or more, depending on how much of the deck has to come apart to access the footings.

We've built decks across King County for years — from flat Renton lots with clean outwash to steep Bellevue hillsides where we've drilled helical piers 10 feet down to reach competent material. Every one of those projects started with a conversation about soil, not about decking colors. If you're starting to plan a deck on a King County lot, we'd like to have that conversation with you.

Call us at (425) 675-6259 or visit our contact page to schedule a site visit. We'll look at your soil conditions, your slope, and your drainage before we spec a single footing — because that's the only honest way to build a deck that stays level for the life of your home.