Warping fence posts

[Dan Karachio]

I need some trusty advice. A few years ago we paid to have a cedar fence put in our back yard. It came out nice, but the posts, made of pressure treated wood 4×4, are twisting and it is causing issues with the gate and parts of the fence. It just looks bad. There is no possibility of the fence company taking responsibility, so I am thinking about replacing them. If I were to use PT again, what should I look for to avoid getting 4×4 wood that warps? Could I buy it and let it sit for months before I use it – dry it out? Any other ideas? Since each is buried in the ground (mixed with concrete), do I dare use non treated wood? 4×4 cedar posts are not cheap and I hesitate to even think of using that - or should I? The fence panels themselves are perfectly fine (they are cedar). Those darn posts.

[Tony Bilello]

One way to avoid warping is to not buy from Home Depot.

[Fred Belknap]

Dan, PT lumber just seems to do that and more. I have seen it twist, warp, crack. I think it is mostly caused by moisture. PT comes in with high moisture content, probably has something to do with the treating process. I have found that if I seal the wood as soon as it is in place it helps but doesn't completely prevent warping. This goes against conventional practice. My theory is that it lets the lumber dry out in a more uniform way. My 2 cents.:)

[Lee Schierer]

More and more 4 x 4 posts are the center core of larger trees or made from small trees that have no other commercial value, hence the poor quality and high knot to straight wood ratio. Twisting and warp are almost unavoidable.

Get posts with as few knots as possible or switch to 4 x 6 posts which seem to have better quality.

[glenn bradley]

I agree it is sad; I have PT lumber that has been outside for years and is fine. Some I bought a couple months ago had to be replaced due to twists after installation (what a pain). I assume they are doing the PT to poorly prepared material but don't know for sure. I have switched to pipe with the plastic sleeves for fencing repairs and add-ons.

[Scott T Smith]

You have several choices. If you want to stay with pressure treated pine, buy posts labeled "KDAT", which stands for "kiln dried after treatment" from a commercial supplier - not a BORG. Most pressure treated posts are kiln dried before treatment, which is not as good.

Or - replace with cedar or another rot resistant wood. Species that come to mind include black or yellow locust (stay away from honey and white locust), white oak, Osage Orange (also called Bodark in some regions). I would not use concrete around the posts, with the exception of the gateposts.

Where do you live? Any chance of buying rot resistant posts from a local miller?

[Gary Herrmann]

I put in a new fence recently. I went with cedar posts as well as panels to avoid this in the long run.

[Matthew Hills]

More and more 4 x 4 posts are the center core of larger trees ...

I've heard this is a problem, but haven't been able to reason out why. If the post is symmetric about the center, I'd expect it to be stable. Is the argument that it will move a lot with even a little asymmetry?

I was wondering about this because of a recent Schwarz blog post about building a workbench out of cores.

Matt

[Jim Rimmer]

I would suggest going to a reputable fence supply store and talking with them. I replaced a portion of a wood fence with borg cedar and it is bowed, twisted, etc. after a couple of years but in an area where it only bothers me. I replaced a portion between the driveway and patio and got the wood from a fence supply. It cost a little more (but not a lot more) and it is still as straight as the day I put it up.

[Neal Clayton]

I've heard this is a problem, but haven't been able to reason out why. If the post is symmetric about the center, I'd expect it to be stable. Is the argument that it will move a lot with even a little asymmetry?

I was wondering about this because of a recent Schwarz blog post about building a workbench out of cores.

Matt


because the center is the weakest portion of the tree.


One way to avoid warping is to not buy from Home Depot.

/agree

[David Helm]

Pressure treated wood, when it comes from the vat, is very wet. Sometimes it twists and sometimes it doesn't. I find that what we get here in the Northwest (Western Hemlock) is generally pretty good and comes from fairly big trees. Definitely avoid the center of the tree because it remembers the spiralness of the growth. Any cedar you can get today is second growth and does not have the rot resistance of old growth. It takes many years (as in hundreds) to develop the degree of resin that produces the rot resistance. As someone else said, avoid bying your lumber from the BORGs.

[Henry Ambrose]

You have several choices. If you want to stay with pressure treated pine, buy posts labeled "KDAT", which stands for "kiln dried after treatment" from a commercial supplier - not a BORG. Most pressure treated posts are kiln dried before treatment, which is not as good.
snipped......


Yep! If you can find/order some KDAT your problem is mostly fixed. It will cost more than wet treated wood. The other way to do this is to buy whatever PT you can and lean it up under cover and let it dry for a few months. Once its dry it'll be finished warping and twisting and you can put the straight ones in the ground.

[Dan Karachio]

Thanks everyone, I will look for some KDAT and add a little bit of extra checking by letting it sit for a while since I will probably not get to this until next spring. It's too bad the fence company, where you would expect expert knowledge, doesn't know (or care) as much as all of you!