Vintage View: How to deal with wet and dry rot in your home

Typical wet rot shows up where there is a failure in the plumbing or ingress of water into timber as here with this soft old window frame. Once dried out and treated, the rot will only return if the surface gets wet again (the spores are already present).
When we were kids, our mother would find the furriest boreen in whatever county we happened to be roaming around, and buy whatever hoary old building was at the end of it. She would fly into an instantaneous passionate panic — offering the full asking price if the seller would take it off the market.
At least, that seemed to be her property buying mechanism.