Decks

Composite vs Wood Decking in Western Washington: Cost, Rain and Upkeep

If you are building or replacing a deck in western Washington, the first big choice is the boards. Here is how composite and wood compare on cost, on rain, and on the work each one asks of you.

What each one costs

LawnLove's 2026 composite decking guide puts the boards alone at these prices per square foot:

Installed, the same guide puts most composite decks at $25 to $50 per square foot, or about $10,000 to $20,000 for a 400 square foot deck. Other guides put the same deck as high as $32,000, and our Thurston County deck cost guide lays the figures side by side.

How long each one lasts

LawnLove puts the typical life of pressure treated wood at 10 to 15 years, cedar at 15 to 20, and composite at 25 to 30. Most composite decking also comes with a warranty of at least 25 years.

That changes the math. A composite deck can cost more on day one and less over its life, because you may build one composite deck in the time you would build two wood ones.

Wood in our rain

Wood is lovely, and cedar in particular suits a Northwest home. But it needs looking after. In this rain, pressure treated decking needs staining every year or two to reach its 10 to 15 years, as we explain in deck repair or replace.

Skip the sealing and wood goes gray, then starts to crack and soften.

Composite in our rain

Composite does not rot, so the boards themselves hold up well to a wet winter. It is not maintenance free, though. Trex, one of the biggest composite brands, says mold can grow on the film of pollen and dirt left sitting on the surface. Its advice is to clean it off with a hose, warm soapy water and a soft brush.

On a deck under trees, plan on a good wash in spring and fall. Trimming back overhanging branches helps too.

One more thing. Composite boards usually sit on a wood frame, so the frame underneath still needs to be built for the wet, with good drainage and posts on concrete footings.

Composite or wood: how to choose

• Tight budget, or a deck you may replace in 10 years? Pressure treated wood.
• Want real wood and do not mind sealing it? Cedar.
• Want to stop staining, and staying put for the long run? Composite.
• Deck under trees or in deep shade? Either works, but composite will not rot, as long as you wash it.

Where to go from here

We build decks in both wood and composite across Thurston and Pierce counties. For ideas, see deck design ideas, or our decks and patios page.

Tell us about your deck, its size and how much shade and rain it gets. We will tell you which material makes sense and what it would cost.

Code requirements on this page were last checked on 29 October 2026. Codes change, so confirm current standards with your city or county before you apply.