Robert Green wrote:

In my youth, we bought creosote by the gallon and poured it around
the piers under the house. Worked very well.

Can you still buy creosote? I thought it got banned by the EPA, too.

Nah, not banned. According to Wikipedia, it's the most widely used wood
preservative in the world. When I was a kid, we had a creosote plant down
the street. They took, mostly, tree trunks and turned them into telephone
poles.

The tree trunks came in on railroad flat cars which went into a GIANT
pressure cooker - car and all. After a couple of hours of heat-impregnating
with the creosote, a switch engine pulled the flatcar with the finished
product out and inserted another. I think they also did railroad ties and
piers.