If its a barn, I'd treat it the same way as a garage slab. We put control joints in 10'x10' sections here. You can do isolation joints if you want but if the dirt is compacted good then control joints should work fine. I'm assuming you know the difference? Isolation joints allow for better vertical movement.aflowers said:Pouring pole barn... so do you think its better to do a saw cut and leave the expansion joint out?