There are building techniques that will survive for only a few years, then there are methods that will result in materials lasting for many, many years. A classic example of non-durable, short term, construction is the way many contractors pay no heed to the consequences of moisture wicking up into wood.
The photo above is a wood column that supports an overhang roof. The overhang protects part of this concrete patio from rain but not the edge. And, where the post rests on damp concrete, rot-decay was developing. Even pressure-treated lumber lasts longer if it is not damp all of the time. How much better it would have been, in this instance, to install the column on a steel saddle bracket post base that was embedded in the paving.
Another common area, to find such a problem, is trim at the sides of garage vehicle doors.
So far, the wood above is holding its own but, over time, decay is probable. Wood trim at the exterior, areas exposed to moisture, should be separated, 1" gap minimum, from pavement or a flat surface. The photos above are only two examples of contractors taking short cuts. In the first instance, a bit more work would have been involved in installing steel connectors to posts at the landing. In the second photo, it would have been just as easy to do it right the first time: install the wood trim with space at the bottom. From what I can tell, at least in Bellingham and Whatcom County, the problem is two fold -- many contractors do not know any better. Then there is the whole other group -- those that know better but they don't care!