6x6 FencePosts

I am planning on putting a fence up. I want to use 6x6 posts. I was going to dig the holes about 46-48 inches deep and put gravel at the bottom. I then intend to put a couple of bags of cement in and then just tamp dirt on top of that. Does it really matter if I get the .40 or .20 treated posts? I can't forsee a 6x6 rotting out in 15 years even if it is the lower treated type. I used 6x6 as corner posts for another fence I put in and cemented them in as I intend to do with this fence. After 5 years you could run a truck into those posts and they wont move. They were the .20 treated posts and I don't see any rotting whatsoever. I know the .40 posts are more expensive. I thought I was overkilling it by using 6x6s and then someone said you need .40 treated 6x6s. What would be the lifespan of .20 vs .40 treated 6x6s ? Thanks for any responses

The problem with 6x6 posts is that there is minimal penetration into the center core of the timber. The inevitable cracks in that size post will allow moisture to enter the center core and will rot the timber from the inside out.

I would use ground contact (0.40) rated treated timbers for work that involves ground contact. Something worth doing is worth doing right.

The cement will cause the posts to rot faster. I would just tamp them in -- but if you are worried about uplift, then nail a piece of wood to the bottom of the post to create a 'T', and then after tamping, it would have to be quite a strong pulling force to yank it out of the ground.

What type of fence are you building? If you are building a high-tensile fence, I would go with round posts instead of square ones.

I'm building a 3 rail post and board fence. I looked at the 6x6s the other day and they said Ground Contact on them. They had a .21 CC-B type preservative.

Not to steal gator22 thread, but have any of you found alternatives to pressure treated posts and the lifespan of other products?

lloyd

I'd go with a minimum of .4 pcf retention for ground contact.

Hedge posts will outlast anything treated or non-treated.