Fencing
Pressure-treated posts vs cedar
Are pressure-treated fence posts bad?
Pressure-treated wood resists rot but does not stop it, and the treatment is weakest exactly where the post needs it most — at the soil line. That's why we don't set fences on them.
Where posts actually rot
A post does not rot evenly. It rots in a band a few inches above and below where the wood meets the dirt, because that's the only part of the post that is simultaneously wet, warm, and exposed to air. Bury it deeper and that band just moves down with it.
Everything above that band can look perfect. That's what makes it deceptive — the fence looks fine right up until a decent wind takes a section down, and the break is always at the dirt line.
What the treatment actually does
Pressure treatment forces preservative into the outer layer of the wood. It genuinely slows decay, and for a deck joist that stays dry and ventilated it is the right material.
A fence post is a different problem. It is buried, it stays damp, and any cut end or drilled hole opens untreated wood straight to the soil. The protection is a shell, and burying the post is how you find the parts the shell doesn't cover.
What we use instead
Steel posts, or cedar set properly in concrete with the crown shaped so water runs away from the post rather than pooling against it.
The cost difference shows up once, at install. The difference in outcome shows up at year six, when one fence is leaning and the other isn't.
Rot is patient. Build like it's coming, because it is.