Is wood the worst choice for building decks with?
The short answer is that wood can be the worst choice for building your deck--if you choose the wrong type.Wood is porous. The above photo is a zoomed in photo of the end grain of oak. All the little holes you see will wick in moisture--add moisture along this end grain and it will draw into all the little spaces naturally. Thats how trees send nutrition from the roots to the trees, through all these little spaces.
If you build a deck from SPF (Spruce, Pine, Fir), which is typically framing materials, you won't get anywhere near the durability of a deck made of Redwood, Cedar or Tiger Deck. If you are very fortunate and you seal the end grains you may get 5-7 years out of your deck.
Build a deck from poplar and even if you seal all 6 sides you will find it unstable and vast parts and connections entirely missing within the first 5 years. Poplar is one of the fastest growing trees and also rots very quickly. When it rots it nearly disappears within a couple of short years.
Eastern White Cedar is a similar species to Red Cedar, however it is a much smaller tree and for that reason is a lower quality cut of lumber with large cracks and loose nots. Eastern White Cedar grows in a dry climate--where Red Cedar grows in a Tropical (very wet), climate. Any species exposed to extremely wet climate will develop tools to cope with the excess moisture--and when you take that species into a dry climate like the central plains you get an extremely long lasting deck.
Pressure treated lumber is strong--but brittle, and if a builder is not well trained you can end up with dangerous events like this one. This lady had serious injuries when this stair failed and the builder was sued successfully for damages--even though he was her ex boyfriend.
Here is what a Red Cedar Deck looks like when it is well done. Pre-finished to fill the end grain pores, and solid stain on the rails. The builder even used exterior suitable fiberglass clad plywood for the large posts.
For information about Composite Decking Materials click here
For information about Staining Wood Decks click here