The previous homeowner installed a behemoth "wrap-around" deck on my split-level in the Pacific NW (500 yds from Puget Sound) about 12 years ago. The back deck is probably about 16 x 18, the rail portion of the portion runs about 25 feet along the side of the house, maybe 25 x 8, then the front porch is probably about 10 x 14. I estimate I'm probably dealing with about 700 sq feet of decking.

Anyways, after spending the past couple days ripping out, replacing, and staining rotted or water-damaged planks (I have an additional couple of days ahead of me of more of the same), I've concluded after replacing about 25% of the planks in the "front deck" that the decking in this portion is at risk due to combination of excess moisture/lack of direct sunlight.

This "front" deck gets 3-4 hours of sunlight in the 2 months before/after the summer solstice, down to a grand total of zero direct sunlight at the winter solstice (meaning there's approximately 4 months of the year where no sunlight hits this deck). My believe is that during the fall-winter-spring the deck gets wet, and stays wet. This part of the deck has the greatest mold problem.

Anyways, I've concluded that in about 2 or 3 years I want to re-plank this "front" deck with a totally synthetic or plastic decking material. MOISTURE TOLERANCE is my primary concern, as I want a material like a plastic that has no wood in it. HEAT GENERATION (from solar light/sunlight) is not a concern, due to the evergreen canopy which keeps sunlight off of this area for most of the year (and besides, our Pacific NW sunlight is not that hot). My direct sun exposure is only about half the year, and all of the exposure is 4:30 p.m. and later.

Recommendations and helpful hints welcomed!!!

I just ripped up a rotten cedar deck - from the ground up. Nothing left. Rotten joists, rotten decking, rotten construction techniques. There were a few good boards, but I just kept the better CCA if needed for the new deck.

Rather than all plastic, I am looking at composites. McLendon's stocks TimberTech. I have some samples of Moisture Shield although no one locally stocks it. Their regional sales rep in Beaverton OR says they can work with McLendon's and a few others in this region. I wouldn't even have a deck, but the topography requires it to make a useful area in the back. The deck will shrink and patio will expand.

If cost is no object and esthetics are flexible, you might look at LockDry aluminum decking. If I lived close to the sound this is what I would get. Probably as close to zero maintenance as possible. My wife was extremely interested in it until we got the samples: hard to disguise aluminum.

I'd also suggest checking the ventilation under the deck - that may be more important than the lack of sun.