How long will preasure treated lumber last if its on the ground or partially in the ground?

Question

Maybe using it to put in a deck, the face of the deck would be six inches off the ground with good drainage.

Answer 1

You can prolong the life of the part underground by using the concrete rather than the metal spike setting method. Make sure that the wood isn't  in contact with soil or standing water and treat anything above ground every 5 years with wood preserver.

Answer 2

20+ years

Answer 3

If looked after it will last for 10+ years. Timber in the ground will last less.

Answer 4

should be 25 years

Answer 5

Will probably never have to replace any part of the deck due to rot.  I use treated wood on lower deck structures only, to save cost.