New Deck Construction in Kent, WA
From the first site visit to the final inspection: what a new deck costs in Kent, what the city needs to see, and the details that keep a frame dry through a south King County winter.
What a New Deck Costs and When It Needs a Permit
A homeowner in Kent pricing a first deck usually wants two numbers before anything else: what it will cost and whether the city is involved.
A new deck in Kent runs about $35 to $75 per square foot installed, cedar low and composite high. Any deck more than 30 inches above grade needs a building permit and a 36-inch guard; an attached deck needs the permit at any height.
Both numbers depend on the house. A ground-level platform off a rambler on the valley floor sits at the bottom of the range and can sometimes stay under the permit line. A deck off the upper floor of an East Hill split-level sits at the top, because the posts are eight feet long, the stairs need a landing, and the ledger carries a load the inspector will want to see bolted correctly. The cost guide works through the ranges by size and material; this page is about how the deck gets built.
The Decisions That Set the Price
Attached or freestanding
Most Kent decks attach to the house with a ledger board bolted through the siding into the rim joist. It is the cheapest way to support one side, and it is also where decks fail: water gets behind the ledger, the rim rots, and the bolts have nothing to hold. Washington's deck section requires lateral-load hold-downs at the ledger on an attached deck, two rated at 1,500 pounds or four at 750, and a proper flashing detail above and behind it. A freestanding deck on its own posts a few inches off the house avoids the ledger entirely, costs a little more in footings, and is the standard answer where the siding is stucco, brick, or a cantilevered floor that cannot take a ledger.
Height above grade
Thirty inches is the line for both the permit and the guard. Below it a deck can be built without a rail and, if it is also detached and under 200 square feet, without a permit. Above it the guard is required at 36 inches minimum with openings that stop a 4-inch sphere, and the guard has to resist a 200-pound load at the top rail, which is why a wobbly rail is a code failure and not a cosmetic one. Every foot of height also adds post length, bracing, and stair run, so a deck at door level on a two-story house is a different project from the same footprint at grade.
Decking material
Pressure-treated fir is the budget option and the one most likely to check and twist in the wet-dry cycle. Western red cedar is the regional standard for looks and holds up for 15 to 25 years with cleaning and a reseal every two years or so. Composite and PVC cost more per foot and remove the maintenance cycle. Whatever goes on top, the frame underneath is pressure-treated lumber rated for ground contact where it touches soil or concrete, with hot-dip galvanized or stainless fasteners, because the copper in treated wood eats plain steel.
How a Kent Deck Gets Built
- Site visit and design. The builder measures, checks the rim joist and siding, looks at the slope and the soil, and settles the footprint, height, stairs, and railing. On a corner or a small East Hill lot the setbacks in Kent's zoning code decide where the deck can go.
- Permit. A site plan and framing drawings go to the City of Kent's permit center, or to King County for an unincorporated address. Review takes weeks, not days, so it starts before materials are ordered.
- Footings. Holes are dug to solid bearing, at least 12 inches below undisturbed ground under the state code and deeper where the ground is soft. On East Hill that usually means reaching the dense till under the topsoil; on the valley floor it means a wider pad on silt. Concrete is poured, post bases are set on top, and the inspector looks at the holes before the pour.
- Frame. Posts, beam, ledger with flashing and hold-downs, joists at 16 inches or 12 for composite, blocking, and a self-adhered tape over every joist top so the screw holes stay dry. Framing inspection.
- Decking, stairs, and rail. Boards gapped for drainage, hidden or face fasteners, stringers on their own footing, guard posts through-bolted to the frame.
- Final inspection. The city signs the permit off, and the deck is on the record for the next buyer.
On site, a simple single-level deck takes two to five working days; a two-level deck with stairs and a landing takes a week or more. The permit review in front of it is the part nobody can shorten.