Most composite decks around Snohomish County and the Seattle area land between $60 and $100 a square foot installed, cedar between $40 and $65. A standard 300 square foot composite deck mostly comes out between $18,000 and $30,000. Those numbers are the market talking, not a bid on your deck. Two decks the same size can still price very differently, and it is not the contractor being cagey. Here is what moves the number in your own backyard.
How much do size and height matter?
Square footage is the starting point, but height matters just as much. A ground-level deck is straightforward. A second-story deck off the kitchen needs taller posts, more framing, and stairs, which is a real jump in labor and material.
What do railing and stairs add?
Railing is often the quiet cost. Cable, metal, and glass all run higher than standard wood, and every run of stairs adds framing. A simple rectangle with one short step is far less than a wraparound with lit railing down to the yard.
Composite or cedar, which costs more?
Cedar costs less to build and wants sanding and stain every couple of years. Composite like Trex or TimberTech costs more up front and asks almost nothing after. In our wet climate a lot of homeowners pick composite for that reason, but we build both.
Why do footings decide the real price?
Code footings that the inspector signs off on are not where you want the cheap bid to save money. Skimp there and the deck moves. We pour proper footings and meet the inspector, so what holds up your deck is not the part nobody checked.
Common questions
Tell us the size, how high the door sits off the ground, and the railing you're leaning toward. We'll quote it in composite and cedar so you can watch what each choice does to the number.
