Wood fence post replacement

[Lakewood90712]

I'm replacing some rotted out below the soilline 4 x 4 fence posts at dad's rental house. They were installed by a fence builder 11 years ago , redwood (not clear heart redwood). Embeded in concrete ablot 8" below the soil line. That is where the trouble starts.

They looked great , very sturdy for about 8-10 years. I have replaced a few with the steel base repair thingys available at home improvement stores. They work ok for a post here or there, but don't work for gate posts ( to flexable at the base connection ).

Clear heart redwood is out of the question due to cost and availability. Chemical pressure treated wood is out too . I will not put anything toxic in the soil .

My nut brain idea is to apply one layer of fiberglass cloth resin to the lower end of the replacement posts , with protected area ending above the soil line, and embed in concrete as the originals.

Any Ideas?

 

[Nords]

One option would be to replace the gate posts with galvanized steel posts, and attach the gate hardware to the steel posts. You could paint the posts to match or build a redwood box around them.

Another option would be to replace the gate posts with PVC. The PVC base is set in concrete and the post is filled with grout, so it's pretty stable. The issue would be finding a matching PVC color, or cladding it with redwood (preferably before you fill the PVC with grout), or else replacing enough of the redwood fence with PVC to make the transition look natural.

We ended up replacing our rental property's entire front yard fence (including two gates) with PVC. Zero maintenance.

Which is more toxic to the soil: today's pressure-treated wood or fiberglas resins? I don't know the answers, but if you're discarding those options out of hand then you might want to check into the latest changes. Arsenic and copper aren't used much anymore.

 

[painterbill]

Replaced fence posts embedded in concrete last year, thought with a couple of bars I would (with help) be able to dig a little around the top and pry the concrete out of the ground---wrong. Since I couldn't get the tractor around to the fence area I thought I could use my 2 ton engine hoist and pull them straight up and out---wrong- bent the hoist frame. Eventually dug out one side of the base to pried them over and then out, probably about 120-180 of concrete per hole. But anyway if you do concrete them back in, place tamped soil or gravel in the hole and a couple of inches up the post then the concrete. The soil or gravel will allow any water that sneaks downs the post a way out instead of the concrete acting as a bucket to catch the water and accelerating the rotting process.

 

[samclem]

Sorry, but the fiberglass cloth with epoxy resin won't work--the moisture >>will<< get in there, and it won't get out.

If you go with wood/concrete, painterbill's suggestion to have gravel n the bottom of the hole is a good one. Also, slope the top of the concrete to shed water around the hole rather than into the post.

The newer treated wood is a lot safer than the old stuff. And the 4x4s are treated for "ground contact" which means it'll last for 20+ years when buried. The redwood has toxins too--something is killing those mold spores that would love to colonize that cellulose. "Natural" does not mean "healthy".

PVC is good stuff, and maybe if you are worried about strength/bending in gatepost applications put a length of rebar inside and fill it with concrete grout mix. "That ain't going nowhaar."

 

[pb4uski]

I would lean towards either PT or cedar and skip the concrete. Set the post and then fill the hole with stone dust. Fill hole with 6-8" of stone dust then sprinkle with water and compact with a tamper, then repeat until hole is filled.

Where frost is an issue (like around here) we sometimes out the 4x4 post in a piece of Sch 40 pipe. A flat stone at the bottom of the post hole, then put in Sch 40 cut to be just a bit higher than grade and secure with compacted stone dust or concrete. Then the wood post slips inside the Sch 40 tube. If the frost heaves the ground by the post, the tube slides up (and down when thaw) but the post stays where it is supposed to be. We put my pool house and a deck using this approach and have not had any problems.

 

[veremchuka]

I don't know where you live but around here the choice, if it must be wood, would be locust or red cedar. Locust posts are like galvanized steel, good for about 75 years but there are different locusts and I'm not sure which has the best longevity but your fence company would. Red cedar is good for about 50 years. Naturally small diameter posts like 2" would rot faster than say 5". I used 2" cedar years ago, but probably not red cedar, and one was very lose - if i pushed it gently it'd have broke off at ground level. I just bought 2 42" long 3.5 to 4" diameter red cedar and rehung my garden gate. I figure it'll out last me by a few decades. No concrete involved buried them 18" deep.

 

[JPatrick]

The fiber glass might be worth a shot if you actually affix the glass to the lower part of the post. By that I mean mix up the resin and proceed like you were making a repair. The key is to keep the moisture away from the wood.