I bought a farm with lots of rotted wooden fence posts. I’ve replaced them, but others are going to rot. They are round, and rotted from the inside out. I’ve trying to figure out a way to stop the rot from the top. They are pressure treated, and painted…
The tops should be cut at an angle, so rain runs odd them and doesn’t pool on top. So if you are handy with a reciprocating saw, I’d put an angle on the posts. You can apply a deck sealer (I’m told). Never felt the need myself. My fence is 19 years old and no rot - but all my posts (square and round) are angled, not flat.
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Some places put sheet metal caps on top of the posts. The neighboring farm here (when I was growing up & some fences still stood) had an extra top board on its wooden fences that spanned the top of the angled posts, so it met the “normal” top board at about a 70 degree angle (estimate/memory). That both strengthened the top board (pre-electric wire; this farm raised Morgans in the early 20th C, well before my time) and protected the post tops.
Both of the above predate pressure-treated lumber so I don’t know if they really help now.
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are these posts set in concrete? if so the water could very well be seeping into the wood from the bottom up
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Fence posts usually rot from the bottom up, so coating the top won’t help.
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Pressure-treated lumber will rot from any spot where it has been exposed to the elements by cutting, sawing, nailing, or anything that penetrates the exterior. Also, the newer treatments are not lasting as long in the field as the old CCA. If one cut off an end to level the fence line and stuck that end in the hole, then it will rot from the bottom. If one cut the top off after planting, then it will rot from the top. It will also rot around the holes where it was nailed.
Maybe mine is the “old” type pressure treated lumber. It was installed Feb 2002. I have no rot (to date).
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My fences were installed in 2005 and have no rot. I never did anything to prevent rot either… Not sure why you have a problem?? This is Florida and we get rain, and humidity, muddy paddocks etc. My old property used to flood, and even then I never had widespread problems. A couple posts by the pond needed replacing, but that was all. I have a very old fence that needs replacing but that is probably 30 years old. Where did you buy your wood?
I buy from Lowes or the local lumber store.
If you dig a hole, do you hit water? Most fences in Florida, are built with the fence posts in water a couple feet down.
How long the posts last here in Florida depends on the soil and drainage. my last farm had great fertile soil but held water
in the soil better than the sandy soil I have now. My last farm with good soil, the fence posts started to rot in 7 years.
So far in the sandy soil here, in my 7th year, I have no rotted posts that I’ve found.
Also the thicker, heavier posts last longer than the skinny ones.
Best wood for no rot is heavy white oak post and planks. We get them rough cut directly from the sawmill for best price. It likely is the type of wood that is causing the rot. We put them below the frost line too.
hummm…white oak only scales at 1360 on the Janka Hardness Scale
this is one of the best measures of the ability of wood species to withstand denting and wear. It is also a good indicator of how hard a species is to saw or nail.
https://tinytimbers.com/janka.htm
up north we preferred to use Locust (hardness 1700) but down here if wood is used Mesquite (if you can find strainght ones) will last nearly forever (hardness 2345)
but we usually use steel drill stem rather than wood
You can paint the tops…angled cut is best…with tar.
that REALLY depends on where in Florida you are. Wellington? Yes, because it was everglades within my memory. Ocala? Lots of sand here so probably not. My fences are 19 years old and although they were NOT the best quality when put in most of them are sound - no longer straight tho, installation company sucked… LOL
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Ok, there’s some misinformation on this thread. First of all, wood treatments only treat the outer layers of the wood post, not all the way to the center. The rot is NOT traveling up from the bottom of the posts. In fact, one good way to deal with rot is to pull a post and sink it back into the ground upside down. The pressure treated end that has been in the ground will almost invariably be in great shape.
When a fence is built, first the fenceposts are sunk in the ground (either through driving or set into post holes), then the boards are nailed, and then finally the tops of the posts are cut with a chainsaw to be level with the top board, and sloping so that water runs off. The treated bottom part of the post never gets cut and so invariably the bottom end of a pressure treated post will be in great shape when pulled from the ground.
When the top part of the post is cut off, the newly exposed center of the top of the post is indeed an untreated area of wood. Therefore, sealing that post top with a heavy coat of fence paint is highly recommended to prevent rot/decay of that post.
Once a post starts to rot, you have a few options. If the rot is affecting where the top board is nailed in, I would consider replacing the post. If the rot is minor, I have seen people fill-in post tops with putty or concrete to stop the rot. It’s not a perfect solution, but it does extend the life of the post a bit longer.
When repainting a fence, a lot of people use sprayers which are quick and economical to get fences painted. In that instance, I would pay a separate person or pay a separate fee to have someone go around and specifically put a heavy coat of fence paint on the top of your posts.
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Thank you, BeeHoney. I wasn’t going to reply to all the people who insisted that my posts with holes in the tops were actually rotting from the bottom! (Silly me for thinking otherwise). I’m not sure what wood was used, but the angled cut didn’t help them. I just replaced 30, and want to try to prevent this from happening again. I’m going to use a lot of paint. and try some sealant tape I found. A lot of things I found would be too toxic.
White oak also doesn’t taste good…so horse tend to avoid chewing on it too. The wood is hard, as in we have to pre-drill the holes to nail planks to post. Only the odd post rotted in like 20 years. Very solid fence. I’m in Canada. BTW we are not putting in hardwood oak floors for durability. It is just rough cut horse fence.
BTW whatever you try to seal it with…the wood has to be extremely dry to apply anything topical for it to adhere and work. So Basically wait for Spring and warmer temps.
