"werwer" wrote in message
oups.com...
I just saw this other post about a deck and it's wood posts and
wondered....

I built my kids a tree house and sank 6x6 treated posts in the ground
to support it (3 feet down, no concrete). How long will these last?
The wood is 'green' treated and purchased from Menards - which isn't
a 'industrial' lumber yard. (I've been told treated lumber varies in
quality)

Location Minnesota - rain and snow.

Some is rated for 20 years ground exposure.