Pressure treated 4x4's in the ground -- what to treat them with to make 'em last?

[jas67]

Since I haven't be able to source locust 4x4's locally, and I need to get this fence done, I'm going to use pressure treated pine 4x4's. Is there anything that I can put on these to make 'em last longer in the ground (like some kinda of tar or something)?

Thanks,
Jay

 

[crusty 1]

Jay, pressure treated should be fine on it,s own.We used to use plain old fence posts that lasted many years.They really don,t rot below ground but at ground level,so if treated they should be fine:thumbsupave

 

[CurlyDave]

I have some 20 year old burried PT wood which I also painted with Coppergreen several times. Pulled some up a couple of weeks ago and it was in very good condition. Painted it twice more with Coppergreen and used it again.

 

[bstrom]

I believe there is a rating for ground contact treatment. Not sure what the letters are anymore but I think most of the Southern Yellow Pine treated posts are. You could paint a preservative on the end grain just to make sure but it will last a long, long time. You can put some gravel down in the bottom of the hole too so the end grain is not sitting on dirt. Depending on the situation you can keep them on top of a cement footing with a metal connector too, but that might not work so well for an unsupported fence.

Ground contact should be .40 PCF. Couldn't remember that.

 

[randy41]

i think you would do better to get treated fence posts and not 4x4's. the fence posts will be treated to the .40 PCF and the pine 4x4's will not be.

 

[mustangsallysdad]

Since I haven't be able to source locust 4x4's locally, and I need to get this fence done, I'm going to use pressure treated pine 4x4's. Is there anything that I can put on these to make 'em last longer in the ground (like some kinda of tar or something)?

Thanks,
Jay

Go to your local Ag store (Southern States) or even Tractor Supply and get treated fence posts...I've also always applied brush grade roof cement to the area that will be in ground contact...they should outlast you when used as such.

 

[JEH412]

I haven't worked much with the new PT wood but I have some posts that have been in the ground going on 25 years and they're still solid. They sit on a base of a few inches of gravel but that's it.

John

 

[tallyho8]

The most important thing to remember whether using treated posts or 4x4s is:
If you cut them off to make them shorter, do not put the cut end in the ground as the treatment does not go all the way through and you will have untreated wood exposed.

Put your cut ends up and treat or cover them.

 

[whistlepig]

Pressure treated fence posts need nothing but a hole to put them. I have some that have been in the ground thirty years. I agree with tallyho8. If you cut an end off it needs to be treated. I had a pole in the ground for ten years. I cut six inches off the top and it rotted out two years later. None of my other fence posts that were set at the same time did this.

 

[Toyboy]

I always measure how deep the botton of post will be in the ground and spray that with auto undercoating. Get it most anywhere for a couple bucks a can and goes a long way.