Can you use Treated Pine for a shed?

Bondy2

I want to extend an old shed. I plan on using pole barn-type construction.  I thought I'd use 100mm x 100mm rough sawn treated pine for the in-ground posts in concreted footings.  And rough sawn Treated pine sleepers for the header beams. Can you tell me how stable is rough sawn Treated Pine? Has it been Seasoned? 

Noyade

Good morning @Bondy2 

"rough sawn Treated pine sleepers"

I have tried 'wet' treated pine in a couple of projects with disastrous results due to warping and shrinkage at it dries. But I had have success with an area using wet sleepers and steel. Well placed steel plate 'disciplined' the warping problem but I must point out these sleepers are positioned for decorative purposes and do not support the structure.