Protecting wooden deck posts and fence posts

[Annahmed]

Hi! I need to know most effective ways for protecting wooden deck posts and fence posts from rotting at ground level. I need DIY tips, thank you!

[Gardenboy]

Hi!

Hope you are doing well. I’ve got some solid tips for you. First off, make sure you’re using the right kind of wood—something like pressure-treated wood, cedar, or redwood. These types are naturally more resistant to moisture and decay. But even with good wood, it’s smart to go a step further and treat the parts that will be underground with a wood preservative. Slap on a waterproof sealant or something like copper naphthenate to create an extra layer of protection.

When you’re setting the posts, throw some gravel in the bottom of the hole for drainage before you pour any concrete. And here's a little trick: don’t encase the whole post in concrete because it can trap water and speed up rotting. Leave a small gap around the post and slope the concrete so water drains away.

Another good move is to elevate the posts slightly above ground by using metal anchors or piers. This keeps them from sitting in water and mud. You could even add vinyl or metal sleeves over the exposed part of the post for extra protection. And don’t forget to check on things every now and then. Reapplying sealants and making sure water is draining away from the posts will help them last much longer. These little steps go a long way in keeping those posts solid for years to come!

[Annahmed]

Thank you Gardenboy! One more thing, I have no idea about copper naphthenate, is it safe to use?

[Annahmed]

You're welcome!

It is a wood preservative commonly used to protect wood from rot, decay, and insect damage. It contains copper, which acts as a fungicide and insecticide, and is combined with naphthenic acid to make it more effective at penetrating wood. It’s typically applied to wood that will be exposed to moisture, like fence posts, deck posts, and railroad ties, helping prevent rot caused by fungi and keeping termites and other wood-eating insects away.

One of its big advantages is that it's relatively safe for residential use, unlike some harsher chemicals. You can apply it with a brush, spray, or even by soaking the wood in it, making it super versatile. The only downside is that it leaves the wood with a greenish tint due to the copper, so it’s often used on parts of the wood that are going to be buried or hidden from view.